CCRV Diagnostic Repair Manual 94468A NP 40G Generac Service

User Manual: NP-40G

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Manual Part No. 94468-A

•

SERVICE
Manual
COMPUTER
CONTROLLED
VARIABLE
SPEED RV
GENERATORS
Series NP-30G and NP-40G

GENERAC

P. 0. Box 8
PHONE: (414) 544-4811

•

Printed In U.S.A.

Waukesha, Wisconsin 53187
FAX: (414) 544-4851

REVISED: 05116/96

SAFETY
Throughout this publication, •oANGERI" and •cAUTION!" blocks are used to alert the mechanic to special
Instructions concerning a particular service or operation that might be hazardous If performed Incorrectly or
carelessly. PAY CLOSE ATTENTION TO THEM.

DANGER!
UNDER THIS HEADING WILL BE FOUND SPECIAL INSTRUCTIONS WHICH, IF NOT COMPLIED WITH,
COULD RESULT IN PERSONAL INJURY OR DEATH.

CAUTION!
Under thl~ heading will be found special Instructions which, If not complied with, could result in damage
to equipment and/or property.
These "Safety Alerts• alone cannot eliminate the hazards that they signal. Strict compliance with these special
Instructions plus "common sense• are major accident prevention measures.

NOTICE TO USERS OF THIS MANUAL
This SERVICE MANUAL has been written and published by Generac to aid our dealers' mechanics and company
service personnel when servicing the products described herein.
It Is assumed that these personnel are familiar with the servicing procedures for these products, or like or similar
products manufactured and marketed by Generac. That they have been trained In the recommended servicing
procedures for these products, including the use of common hand tools and any special Generac tools or tools
from other suppliers.
Generac could not possibly know of and advise the service trade of all conceivable procedures by which a
service might be performed and of the possible hazards and/or results of each method. We have not undertaken
any such wide evaluation. Therefore, anyone who uses a procedure or tool not recommended by Generac must
first satisfy himself that neither his nor the products safety will be endangered by the service procedure selected.
All Information, Illustrations and specifications In this manual are based on the latest product Information
of publication.
available at the

time

When working on these products, remember that the electrical system and engine Ignition system are capable
of violent and damaging short circuits or severe electrical shocks. If you Intend to perform work where electrical
terminals could be grounded or touched, the battery cables should be disconnected at the battery.
Any time the Intake or exhaust openings of the engine are exposed during service, they should be covered to
prevent accidental entry of foreign material. Entry of such materials will result In extensive damage when the
engine Is started.
During any maintenance procedure, replacement fasten~rs must have the same measurements and strength as
the fasteners that were removed. Metric bolts and nuts have numbers that Indicate their strength. Customary bolts
use radial lines to Indicate str~ngth while most customary nuts do not have strength markings. Mismatched or
Incorrect fasteners can cause damage, malfunction and possible Injury.

REPLACEMENT PARTS
Components on Generac recreational vehicle generators are designed and manufactured to comply with
Recreational Vehicle Industry Association (RVIA} Rules and Regulations to minimize the risk of fire or explosion.
The use of replacement parts that are not In compliance with such Rules and Regulations could result In a fire or
explosion hazard. When servicing this equlpmen~ It Is extremely Important that all components be properly
Installed and tightened. If Improperly Installed and tightened, sparks could Ignite fuel vapors from fuel system
•
leaks.

-....._

~-"

-------

------

PART

•

COMPUTER
CONTROLLED
VARIABLE
SPEED RV
GENERATORS
Series NP-30G and NP-40G

•

TITLE

THE AC GENERATOR

ENGINE MECHANICAL

GASOUNEFUELSYSTEM

GASEOUS FUEL SYSTEM

ENGINE OIL & COOUNG SYSTEM

ENGINE ELECTRICAL SYSTEM

TROUBLESHOOTING

SPECIFICATIONS & CHARTS

~--

••
SECTION

Part 1

THEAC
GENERATOR

•

COMPUTER
CONTROLLED
VARIABLE

SPEED RV
GENERATORS
Series NP-30G and NP-40G

1.1
1.2
1.3
1.4
1.5
1.6
1.7

TITLE
GENERATOR FUNDAliiiENTALS
GENERATOR MAJOR COMPONENTS
OPERATIONAL ANALYSIS
INSULATION RESISTANCE
COMPONENTS TESTING
CONTROL PANEL
SHEET METAL

,-Section 1.1- GENERATOR FUNDAMENTALS

•

Magnetism
Magnetism can be used to produce electricity and
electricity can be used to produce magnetism.
Much about magnetism cannot be explained by our
present knowledge. However, there are certain patterns
of behavior that are known. Application of these behavior
patterns has Jed to the development of generators, motors and numerous other devices that utilize magnetism
to produce and use electrical energy.
See Figure 1. The space surrounding a magnet Is
permeated by magnetic lines of force called •flux•. These
lines of force are concentrated at the magnet's north and
south poles. They are directed away from the magnet at
Its north pole, travel In a loop and re-enter the magnet at
Its south pole. The Jines of force form definite patters
which vary In Intensity depending on the strength of the
magnet The Jines of force never cross one another. The
area surrounding a magnet In which Its Jines of force are
effective Is called a •magnetic field".
Like poles of a magnet repel each other, while unlike
poles attract each other.

NOTE: The "right hand rule" Is based on the •current
flow• theory whlch assumes that current flows from
positive to negative. This Is opposite the •electron•
theory, which states that current flows from negative to
positive.
Figure 2. The Right Han Ru e

~H
+

Figure •

Electromagnetic Induction

•

..........

_...,_

_....--

Electromagnetic Fields
All conductors through which an electric current Is
flowing have a magnetic field surrounding them. This
field Is always at right angles to the conductor. H a
compass Is placed near the conductor, the compass
needle will move to a right angle with the conductor. The
following rules apply:

D
0

•

The greater the current flow through the conductor,
the stronger the magnetic field around the conductor.
The Increase In the number of Jines of force Is directly proportional to the Increase In current flow
and the field Is distributed along the full length of the
conductor.
The direction of the lines of force around a conductor can be determined by what Is called the "right
hand rule". To apply this rule, place your right hand
around the conductor with the thumb pointing In the
direction of current flow. The fingers will then be
pointing In the direction of the Jines of force .

An electromotive force (EMF) or voltage can be produced In a conductor by moving the conductor so that It
cuts across the Jines of force of a magnetic field.
Similarly, If the magnetic Jines of force are moved so
that they cut across a conductor, an EMF (voltage) will
be produced In the conductor. This Is the basic principal
of the revolving field generator.
Figure 3, below, Illustrates a simple revolving field
generator. The permanent magnet (Rotor) Is rotated so
that Its lines of magnetic force cut across a coli of wires
called a Stator. A voltage Is then Induced Into the Stator
windings. If the Stator circuit Is completed by connecting
a load (such as a nght bulb), current will flow In the circuit
and the bulb will light.
Figure 3. A Simple Revolving Field Generator
~0~

Alternating Current
A simple generator consists of a coli of wires called a
Stator and a magnetic field called a Rotor. As the Rotor's
magnetic field cuts across the Stator coli, a voltage Is
Induced Into the Stator windings. The amount of Induced
voltage Is equal to the strength of the magnetic field.

Page1.1-1

Section 1.1- GENERATOR FUNDAMENTALS
Alternating Current (Continued)

Electrical Units

See Figure 4. The current alternates according to the
position of the Rotor's poles In relation to the position of
the Stator. At o· and again at 180", no current flow Is
produced. At go• of Rotor rotation, current flow reaches
a maximum positive value. Rotor rotation to 270" brings
another maximum flow of current. However, at 270" the
current flow has reversed In polarity and now flows In the
opposite direction.

STATOR

QQQQQQ

o·

The rate of electron flow In a circuit Is represented by
the AMPERE. The ampere Is the number of electrons
flowing past a given point at a given time. One AMPERE
Is equal to just slightly more than six thousand million
billion electrons per second.

Figure 4. Operation of a Simple

~
t::l

LP'

enerator

J rQOOOOO J
_p

.d~~

0~
b'
N o S

rQQQQQQ
STATOR J
r000000
STATOR J
go·
a:N
0
~o
0

a:s

STATOR

QOOOOO

STATOR

+
90 180

Waveform at 0 & 180°

e e e e
NO CURRENT

t::IOJ.Ot::l

L::P'

270"

AMPERE:

rlo-,,;io 2io

3,60

Waveform at 90°

Waveform at 270°

..e..e-e-e

e--e.e.e.
POSITIVE ALTERNATION

NEGATIVE ALTERNATION

VOLT:

With alternating current (AC), the electrons flow first
In one direction, then reverse and move In the opposite
direction. They will repeat this cycle at regular Intervals.
A wave diagram, called a "sine waveu shows that current
goes from zero to maximum positive value, then reverses
and goes from zero to maximum negative value. Two
reversals of current flow Is called a cycle. The number of
cycles per second Is called frequency and Is usually
stated In "Hertz".

----:nifi-VOL TIs the unit used to measure electrical PRES·
SURE, or the difference In electrical potential that causes
electrons to flow. Very few electrons will flow when
voltag~:: Is weak. More electrons will flow as voltage
becomes stronger. VOLTAGE may be consdlered to be
a state of unbalance and current flow as an attempt to
regaln.balance. One volt Is the amount of EMF that will
cause a current of 1 ampere to flow through 1 ohm of
resistance.
igure 6. Electrical
Conductor of a
Circuit

T
I

I
:

n ts

OHM - Unit measuring resistance
or opposition to flow
,

6 (e-i.! ft) 6t
I

- Unit measuring rate of
current flow ( nurrter of e 1ectrons past a given point)

1
1

1
' - - - - - - - - - - ....v-- - - - - - - - - - - - - - - - ------*'
l_ __ VOLT - Unit measuring force or

'--------------

Page 1.1-2

difference in potential
causing current flow

(\.

Section 1.1- GENERATOR FUNDAMENTALS
OHM:
The OHM Is the unit of RESISTANCE. In every circuit
there Is a natural resistance or opposition to the flow of
electrons. When an EMF Is applied to a complete circuit,
the electrons are forced to flow In a single direction
rather than their free or orbiting pattern. The resistance
of a conductor depends on (a) Its physical makeup, (b)
Its cross-sectional area, (c) Its length, and (d) Its temper·
ature. As the conductor's temperature Increases, Its resistance Increases In direct froportlon. One (1) ohm of
resistance will permit one (1 ampere of current to flow
when one (1) volt of electromotive force (EMF) Is applied.

The magnetic field around the conductor Induces elec·
tromotlve forces that cause current to keep on flowing
while voltage drops. The result Is a condition In which
voltage leads current. When a conductor Is formed Into
a coli, the magnetic lines of force are concentrated In the
center of the coli. This Increased density causes an
Increase In magnetically Induced EMF without lncreas·
lng current. Thus, coils cause Inductive reactance.
Inductive reactance can also be caused by placing an
lnductlon,motor on the circuit which utilizes the current's
magnetic field for excitation.
Figure B. Induct ve Reactance

Ohm's Law
A definite and exact rela·
tlonshlp exists between
VOLTS, OHMS and AMPERES.
The value of one can be calculated when the value of the
other two are known. Ohm's
Law states that In any circuit
the current will Increase when
voltage Increases but resls·
tance remains the same, and
current will decrease when re·
slstance Increases and volt·
age remains the same.

,...----.,::;---=-----.
Figure 7.

L..--------_.J

If AMPERES Is unknown while VOLTS and OHMS are
known, use the following formula:

•

Current Lags Voltage

AMPERES = VOLTS

OHMS

If VOLTS Is unknown while AMPERES and OHMS are
known, use the following formula:
VOLTS = AMPERES X OHMS
If OHMS Is unknown but VOLTS and
AMPERES are unknown, use the following:
OHMS=

VOLTS
AMPERES

CAPACITIVE REACTANCE:
This condition occurs when current leads voltage (Fig·
ure 9). It might be thought of as the ability to oppose
change In voltage. Capacitance exists In a circuit when
certain devices are (a) capable of storing electrical
charges as voltage Increases and (b) discharging these
stored charges when the voltage decreases.

Reactance in AC Circuits
GENERAL:
When direct current (DC) Is flowing, the only opposition to current flow that must be considered Is resistance
(ohms). This Is also true of alternating current (AC) when
only resistance type loads such as heating and lamp
elements are on the circuit. In such a case, current will
be In phase with voltage- that Is, the current sine wave
will coincide In time with the voltage sine wave.
However, two factors In AC circuits called INDUCTIVE
and CAPACITIVE REACTANCE will prevent the voltage
and current sine waves from being In phase.

•

INDUCTIVE REACTANCE:
This condition exists when current lags behind volt·
age (Figure 8). As current flows In a circuit, magnetic
lines of force are created at right angles to the conductor.
The continuous changes In current value (from positive
to negative) cause these magnetic lines to collapse and
build up continuously.

~Current Leads Voltage
CAPACITIVE REACTANCE

Page 1.1·3

Section 1.1- GENERATOR FUNDAMENTALS
Introduction to CCG's
The Initials "CCG• stand for •computer controlled generator•. Such units are different from
conventional generators In that the performance of
the engine and AC generator are more accurately
matched over a wide range of power needs. The
CCG's provide greater efficiency of both the engine
and the generator while malnta•nlng electrical output withln an acceptable voltage and frequency
band.
CCG units have the ability to operate the engine
over a wide range of speeds, while conventional
generators will deliver correct AC frequency and
voltage only at a fixed rpm. The unit's electrical
output Is fed through an AC-AC converter which
reconstructs electrical waveforms to the correct
output frequency.
Unlike conventional AC generators, the CCG can
match engine speed to load requirements. This
provides several advantages, as follows:

0
0

Smaller engines can be used to produce more
power than on a conventional generator, since
It can be allowed to run at a higher speed.
When the load Is reduced, the engine can run
at slower than the usual speeds. This Improves
fuel economy and reduces engine noise.
The CCG unit can be operated closer to Its peak
power point at all times, because output voltage and current are functions of engine speed.
This allows for a much more compact generator
design.

In the diagram. Operation of the system may be
described briefly as follows:
1. The engine Is directly coupled to a permanent
magnet type Rotor, so the Rotor runs at the same
speed as the engine.
2. As the Rotor turns, Its magnetic field cuts across
the Stator windings to Induce a voltage Into the
Stator.
a. The Stator Is a 2-phase type with center tap.
b. Stator AC output frequency Is between 336 and
540 Hertz. This corresponds to engine speeds of
2520 to 4050 rpm.
c. The load requires a nominal AC frequency of
60 Hertz. Thus, the generated frequency Is six to
nine times the desired range.
3. A Frequency Converter changes the high frequency output to a useful frequency, I.e., one that
Is compatible with load requirements of about 60
Hertz.
4. A Voltage Detector circuit senses load voltage
and signals a System Control circuit.
5. The System Control circuit establishes the REQUIRED ENGINE SPEED for correct voltage and
delivers an output to an Engine Controller.
6. The Engine Controller adjusts the engine's
Throttle to change engine speed and establish the
correct AC output voltage.
7. The following facts should be apparent:

LOAD FREQUENCY IS CONTROLLED BY THE
"FREQUENCY CONVERTER" DEVICE.
VOLTAGE IS CONTROLLED BY A "SYSTEM
CONTROL" CIRCUIT WHICH CHANGES ENGINE SPEED TO MAINTAIN A CONSTANT
VOLTAGE AT VARYING ELECTRICAL LOADS.

CCG SYSTEM OVERVIEW:
Figure 10 Is a block diagram of the CCG system.
The major elements of the system are represented

ystem

ROTOR------------THROTTLE

11--------.

ENGINE

FREQUENCY
CONVERTER
ENGINE
SPEED
SENSING
ENGINE
. , _... REQUIRED
1
CONTROLLER
ENGINE
SPEED

Page 1.1-4

VOLTAGE
DETECTOR
..__ _

p::S~YS~T~E~M~:=~-•1

••---t CONTROL

REQUIRED
OUTPUT
FREQUENCY

Section 1.1- GENERATOR FUNDAMENTALS

•

Why Variable Speed Control?

Most electrical loads will operate satisfactorily
only within a relatively small voltage band. In order
to provide useful voltage at larger load currents, It
Is necessary to Increase engine speed.
In conventional AC generators, some form of
voltage regulation Is needed to provide correct
voltage In the full range of load current. This Is
often accomplished by regulating excitation current to the Rotor (field) wfllch then regulates the
strength of the Rotor's magnetic field. The voltage
Induced Into the Stator windings Is proportional to
the strength of the Rotor's magnetic field.

The CCG uses a Rotor having a fixed and permsnent magnetic field. The strength of this magnetic
field Is fixed and cannot be regulated.
The output voltage on CCG generators tends to
droop with Increasing electrical loads. The svsTEM CONTROLLER maintains a constant AC output voltage by Increasing engine and Rotor speed
as the load current Increases, to offset this Inherent
voltage droop.
The SYSTEM CONTROLLER also selects the correct number of generator pulses which are comblned to form each so Hertz "half-cycle" •

•

Page 1.1·5

Section 1.1- GENERATOR FUNDAMENTALS

Page 1.1-6

Section 1.2- MAJOR GENERATOR COMPONENTS

•

Introduction

Upper Fan Housing

Major components of the generator proper are
shown In Figure 1, below. External sheet metal and
other unrelated components are omitted from the
drawing for clarity. TheBe p3rts are:

As Its name Implies, this component houses and
shields the upper cooling fan. See Figure 1, Item
1.

ITEM

1
2
3
4

5
6
7
8
9
10

NOMENCLATURE
Upper Fan Housing
Upper Cooling Fan
Permanent Magnet Rotor
Rotor Hub
Stator Retaining Ring
Stator Assembly
Stator Adapter
Engine
Lower Fan & Flywheel
Stepper Motor

Upper Cooling Fan
The Cooling Fan draws air Into the generator
through slotsln the Upper Fan Housing. It Is fastened to and rotates with the Permanent Magnet
Rotor.

Permanent Magnet Rotor

Sixteen permanent magnets have been affixed to
the Rotor. A starter ring gear is welded to the
Rotor. The Rotor and Hub are balanced at the factory as an assembly and must be replaced as an
assembly.
NOTE: The hub MUST be properly aligned during
reassembly. The mounting bolt, housing opening
and magnet must be properly aligned. In addition,
match marks between the Hub and Rotor must be·
aligned as Indicated by an "AUGN MARKS FOR
BALANCE" decal. During assembly, use care to
avoid damage to the Ignition Sensor.

•

DANGER!
THE PERMANENT MAGNET ROTOR PRODUCES
AN EXTREMELY STRONG MAGNETIC FORCE.
USE CARE DURING INSTALLATION TO AVOID
PINCHED FINGERS.

BALANCE MARKS

•

1. Fan
2. Hub
3. Ring Gear

4. Ignition Cage
5. Rotor
6. Fan Clips

Page 1.2-1

Section 1.2- MAJOR GENERATOR COMPONENTS
Rotor Hub
See Figure 2. The Rotor Hub Is balanced with the
Rotor and must be replaced with the Rotor as an
assembly. Part of the engine Ignition system Is
pressed onto the Hub and can be replaced only as
part of the Rotor and Hub assembly.

sponse to changes In AC output voltage. Thus, In
response to decreasing AC output voltages, the
Motor will Increase the throttle setting and engine
speed will Increase. Conversely, Increasing AC
output voltages will cause the Motor to decrease
throttle setting and engine speed will decrease.

Stator Retaining Ring
The Stator Retaining Ring Is made of die-cast
aluminum. Four hex head capscrews with
lockwashers pass through holes In the Retaining
Ring, to retain the Stator Assembly to the Stator
Adapter (Item 7, Figure 1).

...,_ _ _ 55 (BLACKJ--111(§}
....---66(BROWN)~

(BROWN)

--4IEliW

Stator Assembly
The 2-phase Stator is made up of eight (8) windings, with leads brought out as shown in figure 3.
Figure 4 is a schematic representation of each stator winding. Note that there are four (4) power
phase windings (Leads AC2, AC1, S12, Sl1 and 11 );
a timing winding (Leads TIM1 and TIM2); a power
supply winding (Leads PS1, PS2); and a dual battery charge winding (Leads 55, 66, 77).
The Stator produces a frequency of 336 to 540
Hertz, which corresponds to engine speeds
between 2520 and 4050 rpm. This means the generated frequency is between six and nine times
the desired frequency of about 60 Hertz.

SL1 (ORANGE)--E

SL2 (BROWN)

Stator Adapter
The Adapter Is retained to the engine by means
of four hex head capscrews. The Stator Is retained
to the Stator Adapter and Is •sandwiched• between
the Adapter and the Stator Retaining Ring.

Lower Fan & Flywheel
The Lower Fan and Flywheel are retained to the
engine PTO shaft by means of a conical washer and
an M16·1.50 hex nut. When assembling, tighten the
flywheel nut to 75 foot-pounds.

fm4Joo1
POWER
PHASE 1 t

(OO~t~l

11
11
..........,

AC1

POWER

PHASE 2

r~~\ ~ (W611ll)
SL2

SL1

r:~=l

The engine Is a olngle cycllnder, overhead valve

POWER
SUPPLY
PS1
0

Stepper Motor

Page 1.2-2

BATTERY
CHARGE

type manufactured by Generac Corporation. Depending on the specific generator Model Number,

The Stepper Motor (Figure 5, next page) consists
of a stepper motor along with a gear and cam
arrangement which allows motor movement to
change the engine carburetor throttle setting. The
Motor Is controlled by output signals from the Computer Control Circuit Board, which calculates the
number of steps the stepper needs to take and
generates the required signals to the Motor. The
circuit board signals the Motor to actuate In re-

Engine
either a GN-190 or a GN-220 engine Is used on
NP-30 and NP-40 RV generators.

AC2

nM1

PS2

O~OO)

T1M2

(lfl~l

~l~
55

•

Section 1.2- MAJOR GENERATOR COMPONENTS
F. gure 5. The Stepper Motor

Switching signals from the CCG circuit board are
also delivered to the Genlstor. These signals
switch the Genlstor on and off as required, resultIng In a sine wave output to the load as shown In
Figure 8.
Figure 7.

tator Output lne Wave Pattern

INPUT
FROM
- - t - - t - - - i l - - - t - - t - - - - e - TIME
ALTERNATOR

The Genistor

•

Figure 8. Gen stor Correcte

ne Wave Pattern

GENERAL:
See Figure 6. The GENISTOR Is often called a
"frequency converter" (also see "Introduction to
CCG's" on Page 1.1-4). Its function Is to change the
high frequency AC output of the Stator (336-540
Hertz) to a useful frequency (about 56-60 Hertz).
The Genlstor has no Intelligence of Its own. It Is
simply a high speed switching device which Is
controlled by the CCG circuit board •

The CCG Circuit Board
GENERAL:
The CCG circuit board has several functions as
follows:

GENISTOR

•

GENISTOR THEORY:
The purpose of a "frequency converter" Is to
divide the Stator AC output frequency by an Integral factor to provide a useful output frequency.
Each of the four half-phases of the center-tapped
Stator Is Genistor-controlled.
Figure 7 shows the sine wave output from the
2-phase Stator windings. This output Is delivered
to the Genistor switching module.

1. It controls the operation of the "frequency converter" (Genlstor).
2. It controls AC output voltage under all load
requirements by controlling engine speed.
3. It protects the system against various faults.
FREQUENCY CONTROL:
The CCG board will adjust the number of alternator cycles In one output cycle to control AC output
frequency. The number of cycles Is based on engine rpm and the output frequency will be maintained In the 55-65 Hertz band.
The board uses a "zero crossing" detector to
synchronize an Internal clock. The frequency of the
Stator's waveform Is measured and, with
referencve to the required output frequency, a "frequency divisor" Is calculated. The clrcu1t board
then signals the Genlstor (frequency converter) to
switch on and off at the proper times so that frequency Is maintained in the 55-65 Hertz band.

Page 1.2-3

Section 1.2- MAJOR GENERATOR COMPONENTS
The CCG Circuit Board (Continued)
VOLTAGE CONTROL:

CIRClhT BOARD CONNECTIONS:

The CCG circuit board utilizes a closed-loop,
proportional-derivative controller which regulates
RMS voltage by changing engine speed. The system maintains output voltage at about 115 volts at
the lowest rpm and 120 volts up to the maximum
rpm.
The board controls a Stepper Motor (Figure 5),
which moves the throttle. The board calculates the
number of steps the Motor needs to take and signals the Motor to move. Motor movement changes
throttle position and changes In engine speed result.

The board Is equipped with eight (8) connection
points (receptacles). These are Identified as
"CONN1" through "CONN&•. See Figure 9.
CONNECTOR

FAULT PROTECTION:
The CCG board has the ability to detect several
fault conditions and shut the engine down, as follows:
1. Overvoltage:- If the output voltage exceeds 127
VAC for longer than 15 seconds, the board will turn
AC output power off and shut the engine down.
2. Undervoltage:- If output remains below about 96
VAC longer than 15 seconds, an overload condition
probably exists. The board will then turn AC output
off and shut the engine down.
3. Overspeed:- If engine speed exceeds 4500 rpm,
shutdown will occur.
4. Failure of the Genlstor (frequency converter) will
result In engine shutdown.
5. Loss of output to any circuit connected to the
board will result In engine shutdown.

1o o o

·I

mz
z

CONN1

Six-pin connector Interconnects
with speed control Stepper Motor.

CONN2

12-pln connector Is NOT used on
RV units. An orange ~umper wire
Is connected across Ins 5 & 11.

CONN3

7-pln connector Interconnects with
the Genlstor.

CONN4

4-pln receptacle for connection of
the Stator power supply leads
(PS1, PS2) and the Stator timing
leads (TIM1, TIM2).

CONNS

Single point connection for Stator
lead No. 11 (blue).

CONN6

Interconnects with the Genlstor.

CONN7

Single point connector Is NOT
used on RV units.

CONNB

Single point connector for Wire 188.
Interconnects with En~lne Controller circuit board, al ows the
CCG board to shut the engine down

CONN8

CONN4

FUNCTION

CONN7
~

=
CONNS

-;-

(-----------------~--------------------- \
I
I
I
I

~
CONN3

-o

Page 1.2-4

I· .... HI
c:=:::J

CONN6
0
1···~
1
c:=:::J

I
I
I
I

[g]]~~QQ]
-----------------~~---------------

I
I
I
I

(\J

z
z

•
•
•

:]
•

•

......__
•

r'\

1Section 1.3- OPERATIONAL ANALYSIS

•

General
Figure 1, below, Is a block diagram of the computer controlled RV generator. The diagram Is Intended only for the purpose of Illustrating generator operation. Refer to the actual wiring diagram for
wiring Interconnections.

Operational Description
1. The PERMANENT MAGNET ROTOR Is directly
coupled to the ENGINE and rotates at the same
speed as the engine.
2. As the ROTOR turns, Its magnetic field cuts
across a number of STATOR wlndlngs, to Induce a
voltage Into those windings. A voltage Is Induced
Into the following STATOR windings:
a. Phase 1 and 2 of the. STATOR POWER WINDINGS (output leads AC1-AC2 and SL1-SL2).
b. The STATOR POWER SUPPLY WINDING with
output leads PS1-PS2.
c.The STATOR TIMING WINDING (output leads
TIM1·TIM2).
d. STATOR BATTERY CHARGE WINDING with
output leads 55,66 and 77.

3. STATOR BATTERY CHARGE WINDING output Is
delivered to the unit battery via a BATTERY
CHARGE RECTIFIER (BCR) and a 1 OHM, 50 WATT
RESISTOR. The circuit Is completed through the
battery to frame ground and back to the BATTERY
CHARGE WINDING via Wire 55.
4. STATOR TIMING WINDING output Is delivered to
the CCG CIRCUIT BOARD. The circuit board measures the frequency of the waveform and calculates a •frequency divisor• to maintain a useable
frequency to the CUSTOMER CONNECTION regardless of rpm.
5. The STATOR POWER SUPPLY WINDING output
Is delivered to the CCG CIRCUIT BOARD. This Is
the power supply for operation of the circuit board
and GENISTOR.
6. STATOR POWER WINDING OUTPUT (Phase 1
and 2) Is delivered to a GENISTOR. The GENISTOR
Is a high-speed switching device which Is controlled by the CCG board.
7. The CCG CIRCUIT BOARD senses voltage and
frequency and then acts to control voltage and
frequency as follows:

ystem

•

CUSTOMER
CONNECTION

CCG
CIRCUIT
BOARD

WIRE 188
(ENGINE
SHUTDOWN)

STEPPER
MOTOR

TO BATTERY
GENISTOR

STATOR
POWER
SUPPLY
WINDING
PS1-PS2

MAGNETIC
FIELD

STATOR
TIMING
WINDIN.G

STATOR
BATTERY
CHARGE
WINDING
66-77

•~---------------------------~
Page 1.3-1

Section 1.3- OPERATIONAL ANALYSIS
Operational Description (Continued)
a. The circuit board senses actual voltage and
a compares a It to a pre-set a reference a voltage of
about 115-120 volts AC.
(1) If voltage Is low, the board will signal a STEPPER
MOTOR to change engine throttle setting and Increase speed until the desired voltage level Is
reached.
(2} If voltage goes high, the board will signal the
STEPPER MOTOR to reduce engine throttle setting
until the desired voltage level Is obtained.
(3) Engine speed Is variable and Is used to control
output voltage and may range from about 2520 to
4050 rpm.

Page 1.3-2

b. The CCG board controls AC frequency by r ' \
acting on the GENISTOR.
(1) The GENIST.OR Is a high speed switching
device
•
(2) The CCG board signals the Genistor to switch
generator waveforms on and off at the proper
tlmes, In order to maintain a frequency In the
55·65 Hertz band.
8. The CCG circuit board can protect the system
against some faults by shutting the engine down.
Wire 188 Is the •engine shutdowna lead that connectcts this system to the Engine Controller circuit
board. See "FAULT PROTECTION", Page 1.2-4.

-----------------------------------------------------

Section 1.4-INSULATION RESISTANCE

•

Dirt and Moisture
If moisture Is permitted to remain In contact with the
generator Stator windings, some of It will be retained In
voids and cracks of the winding Insulation. This can
eventually cause a reduction In Insulation resistance and
generator output may be affected.
Winding Insulation In Generac generators Is moisture
resistant. However, prolonged exposure to water, high
humldl~, salt air, etc., will gradually reduce the reslstance o winding Insulation.
Dirt can make the problem even worse, since It tends
to hold moisture Into contact with the windings. Salt, as
from sea air, can also worsen the problem, since salt
tends to absorb moisture from the air. When salt and
moisture combine, they make a good electrical conductor.
Because of the detrimental effects of water, dirt and
salt, the generator should be kept as dry and as clean as
possible. Stator windings should be tested periodically
using a HI-Pot tester or a Megohmmeter. If Insulation
resistance Is low, drying of the unit may be necessary. If
resistance Is still low after drying, the defective Stator
should be replaced.

WIHt:

NO.

66
55
SL2
SL1
AC2
AC1
PS1
TIM1
PS2
TIM2

COLOR
_Blue
Brown
Brown
Black
Brown
Orange
Yellow
Gray
Brown
Orange
Yellow
Gray

CONNECTS TO
Main Circuit Breaker C~l_
Battery Charge Rectifier BCR
Battery Charge Rectifier BCR
Grounding Terminal

G•••••··n
Genlstor G
Genlstor G
Genlstor G

CCG
ClrcuH Board rCBl
CCG Circuit Board CCB
CCG Circuit Board CCB
CCG Circuit Board CCB
Figure 2. Stator Leads
. .- - - - 5 5 (BLACK)~
. . .- - - 6 6 (BROWN)""~~§

(BROWN)

---4IEli:W

Insulation Resistance Testers

•

One kind of Insulation resistance tester Is shown In
Figure 1, below. Other types are commerlally available.
The type shown has a "Breakdown• lamp which turns on
to Indicate an Insulation breakdown during the test.
One common type of tester Is the "Megohmmeter•
which measures resistance In "Megohms".

CAUTION!
When using a Megohmmeter or any other tester,
be sure to follow the manufacturer's Instructions
carefully. All Stator leads must be isolated from
other components, especially circuit boards, before performing tests. The high voltages used In
testing Insulation resistance will damage electronic components.

Stator Leads
The following leads are brought out of the Stator and
connected to various components In the unit:
Figure 1. One Kind of HI-Pot Tester

•

AC2 (YELLOW)-@

~UJ:I-----AC1

(GRAY)--@

SL1 (ORANGE)-e

€]

SL2 (BROWN)

Preparation for Tests
See Stator leads CHART above. Disconnect and Isolate all Stator leads. ALL STATOR LEADS MUST BE
DISCONNECTED AND ISOLATED BEFORE STARTING
THE TESTS.

Test All Stator Windings to Ground
Connect the ends of all Stator leads together. Make
sure none of the leads are touching any terminal or any
part of the generator.
Connect one Tester probe to the junction of all Stator
leads; the other Tester probe to a clean frame ground on
the Stator. Apply a voltage of 1000 volts for about 1
second.
Follow the tester manufacturer's Instructions carefully. Some •HI-Pot" testers are equipped with a "Breakdown" light which will turn ON to Indicate an Insulation
breakdown.
A "Megger" (Megohmmeter) will Indicate the •megohms" of resistance. Normal Stator winding Insulation
resistance Is on the order of "millions of ohms• or "megohms". The MINIMUM acceptable Insulation resistance
reading for Stators can be calculated using the following
formula.
MINIMUM INSULATION
RESISTANCE
(In "megohms")

GENERATOR RATED VOLTS

+1
1000

Page 1.4-1

Section 1.4-INSULATION RESISTANCE
Test All Stator Windings to
Ground (Continued)
EXAMPLE: Generator rated voltage Is "120 VACH.
Divide 120 by 1000 to obtain "0.12". Add "1" to
obtain "1.12 . Minimum Insulation resistance for
the unit Is "1.12 megohms".

Test for Shorts Between Windings
Figure 2 on the previous page shows the. Stator leads
that are brought out of the Stator. Figure 3 Is a schematic
representation of the eight {8) Stator windings. To test
for shorts between windings, proceed as follows:
1. Make sure all Stator output leads are Isolated from
each other and from the frame.
2. POWER PHASE TO TIMING WINDINGS:- Connect one
tester probe to Stator lead No. 11, the other test probe to
Stator lead TIM1. Apply a voltage of 1000 volts. The
Tester will Indicate a breakdown If the windings are
shorted together.
3. POWER PASE TO POWER SUPPLY WINDINGS: Connect one tester probe to Stator lead No. 11, the other
tester probe to Stator lead PS1. Apply 1000 volts. If a
breakdown Is Indicated, the windings are shorted together.
4. POWER PHASE TO BATTERY CHARGE WINDINGS:Connect one tester probe to Stator Lead No. 11, the other
probe to Stator lead No. 55. Apply 1000 volts. If breakdown Is Indicated, the windings are shorted together.
5. TIMING TO POWER SUPPLY WINDING:· Connect one
tester probe to Stator lead No. TM1, the other test probe
to Stator lead No. PS1. Apply 1000 volts. If breakdown Is
Indicated, the windings are shorted together.
6. TIMING TO BATTERY CHARGE WINDING:· Connect
one test probe to Stator lead No. TIM1, the other test
probe to Stator lead No. 55. Apply 1000 volts. If breakdown Is Indicated the windings are shorted together.
7. POWER SUPPLY TO BATTERY CHARGE WINDING:Connect one test probe to Stator lead No. PS1, the other
probe to Stator lead No. 55. Apply 1000 volts. If break·
down. is Indicated, the windings are shorted together.

Results of Tests
1. If testing Indicates that Stator windings are shorted to
ground, the Stator should be cleaned and dried. The
Insulation resistance tests should then be repeated. If,
after cleaning and drying, the Stator again falls the test,
replace the Stator assembly.
2. If testing Indicates that a short between windings
exists, clean and dry the Stator. Then, repeat the tests. If
Stator falls a second test (after cleaning and drying),
replace the Stator assembly.

Cleaning the Generator
.GENERAL:

If testing Indicates that the Insulation resistance is
below a safe value, the winding should be cleaned.
Proper cleaning can be accomplished only while the
generator Is disassembled. The cleaning method used
should be determined by the type of dirt to be removed.
Be sure to dry the unit after it has been cleaned. An
electric motor repair shop may be able to assist with
cleaning. Such shops are often experienced in special
problems {sea coast, marine, wetland applications, etc.).

Page 1.4-2

Figure 3. Schematic· Stator Windings

(ooOot~

fOU4o0111

T
Ab
rm!OI) +.(~CR!l

POWER
PHASE 1 1C1

POWER

PHASE2

SL1

PS1

POWER
SUPPLY

r:.:1

TIM1

PS2
v

T1M2

•

omool....~fi~l
BATTERY
CHARGE

USING SOLVENTS FOR CLEANING:
A solvent Is generally required when dirt contains oil
or grease. Only petroleum distillates should be used to
clean electrical components. Recommended are safety
type petroleum solvents having a flash point greater than
1 oo· F. {38" c.).
Use a soft brush or cloth to apply the solvent. Use care
to avoid damaging magnet wire or winding Insulation.
After cleaning, dry all components thoroughly with moisture-free, low pressure compressed air.

DANGER!
DO NOT WORK WITH SOLVENTS IN ANY ENCLOSED AREA. ALWAYS PROVIDE ADEQUATE
VENTILATION. FIRE, EXPLOSION OR OTHER
HEALTH HAZARDS MAY EXIST UNLESS ADE·
QUATE VENTILATION IS PROVIDED. WEAR EYE
PROTECTION. WEAR RUBBER GLOVES TO PROTECT THE HANDS •

CAUTION!
Some generators use epoxy or polyester base
winding varnishes. Use solvents that do not attack such materials.

•

Section 1.4-INSULATION RESISTANCE
Drying the Generator
GENERAL:
If testing Indicates that the Insulation resistance of a
winding Is below a safe value, the winding should be
dried before operating the unit Some recommended
drying methods Include (a) heating units and {b) forced
air.

HEATING UNITS:
If drying Is needed, the generator can be enclosed In
a covering. Heating units can then be Installed to raise
the temperature about 15"-18" F. (8"·10" C.) above ambient.

FORCED AIR:
Portable forced air heaters can be used to dry the
generator. Direct the heated air Into the generator's air
Intake openings. Run the unit at no-load. Air temperature
at the point of entry Into the generator should not exceed
150· F. (66. C.)•

•

•
Page 1.4-3

Section 1.4-INSULATION RESISTANCE

Page 1.4-4

Section 1.5- COMPONENTS TESTING

•

Introduction
Problems that occur In the computer-controlled
RV generator generally Involve the following systems or components:
1. The engine.
2. The Speed Control System.
3. The AC Generator.
4. The Genistor.
5. Battery Charge Circuit.
6c CCG Circuit Board.
7. Wiring Harness and Front Panel.
This Section will discuss test procedures for the
following components. Also see Part 8 of this
Manual, "TROUBLESHOOTING".
.
1. The AC Generator (Stator).
2. The Genlstor.
3. Battery Charge Circuit.
4. CCG Circuit Board.

Stator Assembly

•

GENERAL:
For additional Information on the Stator, refer to
the following:
1. "Stator Assembly" on Page 1.2-2.
2. Section 1.4, "INSULATION RESISTANCE" •
SYMPTOMS OF STATOR FAILURE:
A. If the engine starts but the Stepper Motor does
not move, and shutdown occurs after several seconds, look for the following:
1. Broken or shorted Power Supply winding
(Wires PS1 and PS2).
2. Broken or shorted Timing winding (Wires TIM1
and TIM2).

0 A short circuit between windings.
0
NOTE: The resistance of Stator windings Is very
low. Some meters will not read such a 1ow resistance and will simply Indicate "continuity". Recommended Is a high quality, digital type meter capable
of reading very low resistances.

TESTING POWER PHASE WINDINGS:
A. Refer to Figures 1 and 2. To test the Power
Phase wlndlngs·for an open circuit condition, proceed as follows:
1. Disconnect the following wires:
a. Lead • AC1• (Gray) at the Genlstor.
b. Lead • AC2• (Yellow) at the Genlstor.
c. Lead •sL1• (Orange) at the Genlstor.
d. Lead •sl2• (Brown) at the Genlstor.
e. Lead No. 11 (Blue) at the Main Circuit Breaker
(CB1).

2. Make sure all of the disconnected leads are
Isolated from each other and are not touching the
frame during the test.
3. Set a VOM to Its "Rx1 • scale and zero the
meter.
4. Connect one VOM test lead to Lead No. 11
(Blue). Then, connect the remaining test lead as
follows:
a. To Lead AC1 and note the resistance reading.
b. To Lead AC2 and note the resistance reading.
c. To lead SL1 and note the resistance reading.
d. To lead SL2 and note the resistance reading.

NOMINAL RESISTANCE- POWER PHASE WINDINGS
0.30 to 0.42 ohm
Figure 1. Schematic· Stator Wlnatngs

NOTE: If the Power Supply winding Is shorted to
round, a burned area on the CCG circuit board
circuit board ground track) may be visible. If the
1mlng winding Is shorted to ground, the circuit will
probably be c/Bmaged but bum-up may not be vlsJble.

B. If the engine shuts down but speed did NOT
exceed 4500 rpm, look for the following:
1. One of the main windings (Power Phase 1 or
2) Is open.
2. One of the main windings (Power Phase 1 or
2) Is shorted to ground.

•

TESTING THE STATOR WITH A VOM:
A Volt-Ohm-Milliammeter (VOM) can be used to
test the Stator windings for the following faults:

0 An open circuit condition.

-~0

r:~:1

POWER
SUPPLY
PS1

TIM1

PS2

•

.......,f'lR'R

o~ool...
BATTERY
CHARGE

TJM2

A "short-to-ground" condition.

Page 1.5-1

Section 1.5- COMPONENTS TESTING
Stator Assembly (Continued)
TESTING POWER PHASE WINDINGS (CONT'D):
B. To test the Power Phase windings for a •short-toground• condition, proceed as follows:
1. Make sure all leads are Isolated from each other and
are not touching the frame.
2. Set a VOM to Its •Rx1o,ooo• or •Rx1K• scale and
zero the meter.
3. Connect one VOM test lead to the terminal end of
Lead .. AC1•, the other test lead to a clean frame ground
on the Stator.
a. The meter should read •Jnflnlty".
b. Any reading other than •JnflnJty• Indicates a
•short-to-ground• condition.

NOTE: Any readfng other than "Infinity" Indicates
the winding Is shorted to ground. If winding Is open
or shortecf, the Stator should be replaced.
Figure 3. "CONN4" 4-Pin Connector

Figure 2. Stator Leads
------55

(BLACK)~

- - - - - 6 6 (BROWN)~
n(BROWN)~

TESTING THE TIMING WINDING:

jJ:~I]'---- AC1 (GRAY)--4'YJ
SL 1 (ORANGE)

--<:::!f

TESTING POWER SUPPLY WINDINGS:
A. To test the Power Supply winding for an open circuit
condition, proceed as follows:
1. Disconnect the 4-pln connector from "CONN4• of
the CCG circuit board. See Figure 3.
a. Stator lead "PS1• (Brown) connects to Pin 1 of
the connector.
b. Stator lead •ps2• (Yellow) connects to Pin 3 of
the connector.
2. Set a VOM to its •Rx1• scale and zero the meter.
3. Connect one VOM test lead to Pin 1 (Lead PS1Brown), the othet test lead to Pin 3 (Lead PS2- Yellow).
The meter should Indicate the resistance of the Power
Supply winding.
NOMINAL RESISTANCE
POWER SUPPLY WINDING
0.35-0.44 ohm

A. To test the Stator Timing winding for an open circuit
condition, proceed as follows:
· 1. Disconnect the 4-pln connector from ·coNN4• of
the CCG circuit board. See Figure 3.
a. Stator lead TIM1 (Orange) connects to Pin 2 of the
4-pln connector.
b. Stator lead TIM2 (Gray) connects to Pin 4 of the
4-pln connector.
2. Set a VOM to Its •Rx1• scale and zero the meter.
3. Connect one VOM test lead to Pin 2 (Lead TIM10range); connect the other test lead to Pin 4 (Lead
TIM2- Gray). The meter should Indicate the Stator
Timing winding re~lstance.

f\..

NOMINAL RESISTANCE
STATOR TIMING WINDING
0.35-D.44 ohm
B. To test the Timing winding for a •short-to-ground•
condition, proceed as follows:
1. Set the VOM to Its "Rx10,000• or •Rx1K• scale and
zero the meter.
2. Connect one VOM test lead to Pin 2 of the 4-pin
connector (Lead TIM1-0range).
3. Connect the other test lead to a clean frame ground
on the Stator. The meter should read •Infinity". Any
reading other than •Infinity" Indicates the Timing
winding Is shorted to ground.

SHORT CIRCUIT BETWEEN WINDINGS:
To test for a short circuit between windings, proceed
as follows:
1. Set a VOM to Its •Rx10,000• or •Rx1K scale and
zero the meter.
2. Connect one meter test lead to Stator lead PS1
(Brown).
3. Connect the remaining test lead to Stator lead AC1
(Gray). The meter should read "Infinity•. Any reading
other than "Infinity" Indicates a shorted condition and
the Stator should be replaced.
11

B. To test the Power Supply winding for a "short-toground" condition, proceed as follows:
1. Set the VOM to Its •Rx10,000• or "Rx1K .. sc·ale and
zero the meter.
2. Connect one VOM test lead to Pin 1 (Lead PS1Brown). Connect the other test lead to a clean frame
ground on the Stator. The meter should read "infinity•.

Page 1.5-2

Section 1.5- COMPONENTS TESTING
4. Connect one VOM test lead to Stator lead AC1,
the other test lead to Stator lead n. The VOM
should read "Infinity".
5. Connect one VOM test lead to Stator lead AC1,
the other test lead to Stator lead TIM1. The meter
should read •Infinity•.
6. Connect one test lead to Stator lead PS1, the
other to Stator lead TIM1. •Infinity" should be
Indicated.
7. Connect one test lead to Stator lead PS1, the
other to Stator lead n. The VOM should read
· "Infinity".
8. Connect one VOM test lead to Stator lead TIM1,
the other test lead to Stator lead n. •Infinity•
should be Indicated.

Genis tor

•

GENERAL:
The •Genlstor" or "Triac Module" Is the FRE·
QUENCY CONVERTER for the generator. For addl·
tlonal Information on the Genfstor, refer to "The
Genlstor" on Pages 1.2·3 and 1.2-4.
SYMPTOMS OF GENISTOR FAILURE:
If the engine shuts down but speed did not ex·
ceed 4500 rpm, the following problems may exist:
1. Loss of the "Gate" connection (G1 through G4)
between the CCG circuit board and the Genrstor.
2. Although the correct "Gate" signal Is received
from the CCG board, one or more switches are not
gating.
3. The Genlstor Is not gating properly, I.e., one or
more switches are permanently turned on.
4. Open circuit or loss of connection(&) between
Stator and Genlstor (Leads AC1, AC2, SL1, SL2,
22).
5. Open circuit or loss of connection between
Genlstor and CCG circuit board (Leads AC1, AC2,
SL1, SL2).
TESTING THE GENISTOR:
Disconnect all wires from the Genlstor before
attempting to test lt.
CAUTION I
DO NOT attempt to test the Genlstor until ALL
leads have been disconnected. The genlstor
MUST be completely disconnected from the clr·
culL If testing Is accomplished with any leads
connected, all test results are Invalid.

•

See Figure 4. To test the Genlstor, proceed as
follows:
1. Set a VOM to a resistance scale that will allow a
range of about 20-60 ohms to be read. Zero the
meter.
2. Connect one VOM test leads to the "COM" terml·
nal and the other test lead to Terminals G1, G2, G3
and G4 one at a time. Read the resistance as the
meter Is connected to G1, to G2, to G3, and to G4.

RESISTANCE READING
•coM• to G1 = 2o-&O Ohms
•coM• to G2 • 2o-eo Ohms
•coM• to G3 2o-&O Ohms
•coM• to G4 = 2o-&O Ohms

3. Set the VOM to its "Rx1" scale and zero the
meter. Then connect the VOM test leads across
the "COM" terminal and the center screw. The
VOM should read "continuity".
4. Now, connect the VOM test leads across the following terminals and screws:
a. Across AC1 screw to AC1 terminal should
read "continuity".
b. Across AC2 screw to AC2 terminal should
read "continuity".
c. Across SL1 screw to SL1 terminal should read
"continuity".
d. Across SL2 screw to SL2 terminal should read
"continuity".
5. Set the VOM to its "Rx1 0,000" or "Rx1 K" scale
and zero the meter. Then, connect the VOM test
leads across each of the screws. There should be
no continuity between any of the screws ("infini-

~1·

NOTE: The resistance reading between any two of
the screws on the Genlstor is in the neighborhood
of about 1 megohm (about 1 million amps). If the
Genistor failed any of the proceeding tests, It
should be replaced.

Testing the Battery Charge Circuit
GENERAL:
The Stator Is equipped with
dual battery charge windings.
These windings deliver an AC
output to a Battery Charge Rectifier (BCR) which rectifies It
(changes It to direct current or
bC). The direct current Is delivered to the unit battery, to maintain the battery In ·a charged
state while the unit Is running •

BATTERY CHARGE

WINDING

Page 1.5-3

Section 1.5- COMPONENTS TESTING
Testing the Battery Charge Circuit
(Continued)
SYMPTOMS OF CIRCUIT FAILURE:
It Is difficult to determine If the battery charge
circuit Is operating without testing for correct voltage. If you suspect the battwery charge circuit Is
defective, the following symptoms will usually
point to a cause of the problem. See Figure 6.
1. If no AC voltage can be measured across Stator
connections at the Battery Charge Rectifier (BCR),
an open circuit condition probably exists In Wire 66
(Brown), or Wire n (Brown).
2. If AC voltage Is available to the Wire 66 and n
terminals at the battery Charge Rectifier, but no
voltage or a low voltage Is measured between the
BCR's Wire 55 terminal and ground, the Battery
Charge Rectifier (BCR) Is defective.
gure 6. Battery

66------,

BATTERY

TESTING THE BATTERY CHARGE CIRCUIT:
Test the Battery Charge winding as follows:
1. Disconnect Wire n at the Battery Charge Rectifier (BCR).
2. Disconnect Stator output Wire 66 at the Battery
Charge Rectifier (BCR).
3. Disconnect Wire 55.
4. Set a VOM to Its "Rx1" scale and zero the meter.
5. Connect the VOM test leads across Wires nand
55, then across Wires 66 and 55. Note the resistance reading In both cases. Replace Stator Assembly, If defective.
BATTERY CHARGE WINDING RESISTANCE
ACROSS WIRES 66 TO 55 0.037.0.042 Ohm
ACROSS WIRES 77 TO 55 0.037-o.042 Ohm

=
=

Page 1.5-4

6. Use a VOM to measure AC voltage at the Wires
66 and 77 terminals of the Battery Charge
Rectifier, with the unit running. If no AC voltage is
measured, an open circuit exists in the wire 66 or
77 circuit.
7. With engine running, use a VOM to check for DC
voltage between the Battery Charge Rectifiers
Wire 55 and frame ground. If AC voltage was present in step 6, but DC voltage is NOT present in
this stem, the Battery Charge Rectifier (BCR) is
defective.
•

Testing the CCG Circuit Board

GENERAL:
It Is difficult If not Impossible to test the CCG
circuit board In the field. Generally, If the other
components In the AC generator system have
tested good, you may assume that any problem Is
In the CCG circuit board.
NOTE: Also refer to "CCG Circuit Board" on Pages
1.2-4, 1.2-5, and 1.2-6.
SYMPTOMS OF CIRCUIT BOARD FAILURE:
1. If. the engine starts, but the Stepper Motor does
not move, and engine shuts down i\fter several
seconds, the CCG circuit board's micro-controller
may not be operating.
2. A failure of the circuit board's Stepper Motor
drive can result In the following:
a. Engine starts, but Stepper Motor does not
move. The engine accelerates uncontrollably ( \
and shuts down when engine speed exceeds
4500 rpm.
b. Engine starts, but Stepper Motor does not
move. The following symptoms occur:
(1} Engine appears to operate too slowly.
(2} Engine Is not able to handle the load and unit
operates at low AC output voltage.
(3) After several seconds under load, AC output
voltage Is turned off (overload condition).
3. If the engine can be started, but shuts down after
several seconds, a timing detection failure may
have occured (Timing winding, Wires TIM1, TIM2).
4. If the engine speed and output voltage are erratic
under constant load, but the AC output does not
tum off Intermittently, erratic timing detection may
have occured (Timing winding, Wires TIM1, TIM2).

NOTE: Timing detection Involves the circuit
board's ability to detect •zero crossings" of the
sine wave {see "Alternating Current•, ~ages 1.1-1
and 1.1-21. ihe CCG circuitoaard must de1ect both
zero VOLTAGE and zero CURRENT crossings If the
system Is to operate properly. This •zero crossing"
detector Is used to synchronize an Internal clock
on the circuit board. The frequency of the Input
waveform Is measured by the circuit board and
checked against a "reference• frequency. The
board then calculates a frequency divisor. By
counting •zero voltage crossings•, an Internal reference output polar~ty Is generated. The Genlstor
switch with the maximum potentia/In the direction
of the Internal reference Is gated.
r'\

Section 1.5- COMPONENTS TESTING

•

TESTING THE CIRCUIT BOARD:
There Is no practical way of testing the CCG
circuit board In the field. Read "SYMPTOMS OF
CIRCUIT BOARD FAILURE" carefully. Test the Sta·
tor, the Genlstor, and the Battery Charge circuit as
outlined In this Section. Also perform a resistance
test of the Stepper Motor (see Part 7, "THE VARIABLE SPEED SYSTEM") and observe Its operation
If possible.
Inspect wiring and wiring connections between
the CCG circuit board and the Genlstor as follows
(refer to appropriate wiring diagram):

1. Check wires G1 through G4 (and Wire 22) for
proper connections at circuit board and at the
Genlstor.
2. Use a YOM to check Wires G1 through G4 (and
Wire 22) for continuity.
3. Check Wires AC1, AC2, SL 1 and SL2 (between
circuit board and Genlstorl for proper connections.
4. Use a YOM to check W res AC1, AC2, SL1, SL2
(between circuit board and Genlstor) for condlnu-

rty.

If all tests are completed and no problem Is found
on other components of the system, replace the
CCG circuit board and check unit operation •

•

Page 1.5-5

Section 1.5- COMPONENTS TESTING

Page 1.5-6

Section 1.6- CONTROL PANEL
Construction
The panel Is constructed of sheet metal and Includes
a panel box, a panel back cover and a front control panel.
The panel box Is retained to an engln~enerator divider
plate by five MS screws. Removal of these screws will
permit the panel to be removed from the divider plate and
set out of the way with connecting wires still attached.
This will allow access to components housed In the
control panel.

Components
A heat sink bracket Is attached to the engine-generator
divider plate, for attachment of a heat sfnk to which a
CCG circuit board and Genlstor are mounted. See Items
26, 31,32 and 381n the Exploded VIew of Control Panel.
Other components are also shown In the Exploded VIew.
Many of these components are part of the •ENGINE
ELECTRICAL SYSTEM• (Part 6 of this manual).

Figurer 1. Exploded VIew o Control Panel

•

ITEM
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
20
21
22
23
24
25

QTY

6
1
1
2
5
8
1
1
1
1
2
1
8
2
2
1
2
4
1
2
1
1
1
1

DESCRIPTION
M5 Pan Head Machine Screw
Back Panel Cover
Control Panel Box
No. 1D-32 Pan Head Screw
M4 Pan Head Screw
M5 Screw
Snap Bushing
90" Connector
Engine Controller Circuit Board
25 amp circuit breaker
M6 Lockwasher
~nltlon Module
5 Lockwasher
M4 Hex Nut
M6 Hex Nut
Ignition Coil Assembly
Ignition Coli Spacer
No. 8 Flatwasher
Front Control Panel
SnaG Bushing
Start- top Switch
Fuel Primer Switch
15 amp Fuse
Fuse Holder

ITEM
26
27
28
~9

31
32
33
34
35
3&
37
38
39
40
41
42
43
44
45
46
47
48
49

QTY

i
1
9
2
1
1
4
4
·j

1
4
1
4
2
1
1
1
1

1
1
2
1

DESCRIPTION
Heat Sink
Battery Charge Rectifier
M4 Lockwasher
No.10-32 Hex Nut
Genlstor
CCG Printed Circuit Board
M3 Pan Head Screw
M3 Lockwasher
1 ohm Power Resistor
500 ohm Power Resistor
M6 Screw
Heat Slnlo: Bracket
M4 Pan Head Screw
M5 Hex Nut
Terminal Block
12-pln Connector
Genlstor Harness
Ground Wire
Customer Wiring Harness
Remote Panel Harness
Snap Bushing
Wiring Harness Clamp
Panel Harness (Not Shown)

Page 1.6-1

Section 1.6- CONTROL PANEL

Page 1.6-2

Section 1.7- SHEET METAL

•

General

See •Exploded VIew of Sheet Metal• on next page. A
DIVIDERPLATE(Item1)8eparatestheACgeneratorcomponents from the engine. The engine hnlf Is enclond
by a BASE HOUSING WRAPPER (Item 4), a FRAME (Item
24), and a BELLY PAN (Item 23). these components are
sealed by means of rubber SEALS (Items 3), to prevent
the escape of gases.

The LOWER FAN attaches to the engine shaft and Is
enclosed In a LOWER FAN HOUSING (Item 19). Air Is
drawn Into the enclosed area around the engine and
forced out of the LOWER FAN HOUSING.
Removal of sheet metal will be necessary for many
repairs and for replacement of most parts.

CONTROL PANEL
BOX

DIVIDER PLATE

•

AIR CLEANER

ROCKER COVER.COVER
OIL FILL TAG

•
Page 1.7-1

Section 1.7- SHEET METAL
Parts List for Exploded VIew of Sheet Metal
ITEM
1
2
3
4
5
6
7
8
9
10
12
13
14
15
16
17
18
19
20
21
22
23
24
25

QTY

DESCRIPTION

ITEM

QTY

DESCRIPTION

1
1
1
1
26
2
4
4
5
7
1
1
1
1
1
1
1
1
1
1
1
1
1
1

Engine-Generator Divider Plate
Engine Upper Wrapper
Rubber Seal
Base Housing Wrapper
M5 Screw
Customer Mounting Ralls
M8 Lockwasher
MB-1.25 Capscrew
MB-1.25 Capscrew
M6 Lockwasher
Spark Arrestor
Exhaust Clamp
318•-16 Capscrew
318• Lockwasher
318• Hex NHut
Air Outlet Deflector
Exhaust Muffler
Lower Fan Housln9
Carburetor Baffle Sk rt
Rock9r Cover Cover
Spark Plug Side Skirt
Belly Pan
Frame
Grounding Strap

26
27
28

1
1
2
3
3
1
1
1
1
4
1
2
1
7
1
1
2
1
1
1
1
1
1

Grounding Strap
Fuel Pump
Barbed so· Fitting
1/4.·20 Hex Nut
114• Lockwasher
Starter Contactor
Starter Contactor Insulator Boot
011 Filter Opening Seal
Seal Retainer
M8 Flatwasher
Fuel Line
Hose Clamp
Snap Bushing
Lockwasher
No.8 Hex Nut
No.8 Hex Nut
MG-1.00 Capscrew
Lockwasher
Grounding Strap
Muffler Heat Shield
Muffler Hanger Bracket
Muffler Lower lnsulaUon
Muffler Upper lnsulaUon

Page 1.7-2

29
30
31
32
33

35
36
37

38
39

41
42
44
45
47

---------

-1

----------------

- - - - - - -

- - - - - -

---·-··--

WII

•

:X:

en
t-,...•
0

(.)

·-...

.....
Q)

en ....~
0
Q)

:t
.(I)

"tJ

~
~

~~~~

~!
~
"J'"PO&IllON

MODEL lo9&&7·l
MUFFLU !XHAUST

_r-..._

C')
I

"':
,_
CD
Cl

Section 1. 7- SHEET METAL

Page 1.7-4

•
SECTION

Part 2
ENGINE
MECHANICAL

•

COMPUTER
CONTROLLED
VARIABLE
SPEED RV
GENERATORS
. Series NP-30G and NP-40G

2.1
2.2
2.3
2.4

TITLE
GENERAL INFORMATION
VALVE TRAIN
PISTON, RINGS, CONNECTING ROD
CRANKSHAFT & CAMSHAFT

•

- - - - - - - -

Section 2.1- GENERAL INFORMATION
Introduction

Figure 1./ntake Stroke

The engine used on Sarles NP-30G and NP-40G recreational vehicle AC generators Is a Generac Series GN190
or GN220, vertical shaft, single cylinder, overhead valve
type.
These engines are not equipped with a mechanical
engine governor. Instead. variable engine speeds are
controlled by a computer circuit board. The circuit board
signals a stepper motor to move the carburetor throttle
linkage.

4-Cycle Engine Theory
GENERAL:
Series GN190 and GN220 engines require four (4)
strokes or cycles to complete one power cycle. This Is
often called the •4-stroke, 5-event• cycle. The 4 strokes
and 5 events that occur are (1) Intake, (2) compression,
(3) Ignition, (4) power and (5) exhaust

F gure 2. Compress on Stroke

INTAKE STROKE (Figure 1):
The Intake valve Is open. The exhaust valve Is closed.
The piston travels downward, creating a suction which
draws the air-fuel mixture from the carburetor Into the
cylinder and just above the piston.

COMPRESSION STROKE (Figure 2):

•

As the piston reaches bottom dead center (BDC), the
Intake valve closes. The exhaust valve remains closed,
as well. The piston starts to move outward In the cylinder.
Since both valves are closed, the air-fuel mixture In the
cylinder Is compressed .

POWER STROKE (Figure 3):
Both valves remain closed. At some point before the
piston reached top dead center (TDC), the spark plug
fires to Ignite the fuel-air mixture. The piston moves to
Its top dead center position and the burning, expanding
gases of combustion force the piston downward.

EXHAUST STROKE (Figure 4):
The expanding gases of combustion force the piston
downward to Its bottom dead center (BDC) position. The
exhaust valve then opens, as the piston starts Its movement toward top dead center (TDC). Piston movement
then forces the exhaust gases out through the open
exhaust valve. The 4-stroke cycle of events then starts
over again.

TIMING:

•

Valve timing and Ignition timing must be precisely
controlled If the engine Is to operate properly and efficiently. Intake and exhaust valves must open and close
In a precise timed sequence If the four strokes are to
occur. Ignition must occur at exactly the correct piston
position, just prior to the start of the power stroke.
Timing of valve opening and closing, as well as of spark
occurence, Is given In relation to the piston position and
the degrees of crankshaft rotation.
Ignition Is timed to occur several degrees before top
dead center (TDC) of the piston, to allow time for the
air-fuel mixture to Ignite and start to bum before the
piston reaches top dead center
There must be no leakage past the valves In their
closed position or compression will not develop. Likewise, there must be no leakage past the piston.

Page 2.1-1

Section 2.1- GENERAL INFORMATION
Recommended Fuels
GASOLINE FUEL SYSTEMS:
For models equipped with a gasoline fuel system, the
use of clean, fresh, UNLEADED, regular grade gasoline
Is recommended. Unleaded gasoline burns cleaner, extends engine life, and promotes better starting by reducIng carbon deposita In the combustion chamber.
Leaded "Regular• grade gasoline may be used If unleaded gasollna Is not available.
The use of gasohol Is NOT recommended. If It must be
used, It should not contain more than 10 percent ethanol.
When gasoline containing ethanol Is used, special care
Is required when preparing the unit for storage (see
"Storage Instructions").
DO NOT USE GASOLINE CONTAINING METHANOL.

Recommended Engine Oil

Use a clean, high quality, detergent oil that Is
classified "For Service SC, SO, SE, SF or SG". Use
no special additives with the oil.

D
0
0

During summer months (above 32" F. or o· C.), use
SAE 30 oil. SAE 10W-30 oil Is an acceptable substitute.
During winter months (below 32" F. oro· C.), use SAE
SW-20 or SW-30 oil.
DO NOT USE SAE 10W-40 OIL.

Engine crankcase oil capacity without oil filter change
Is about 29 fluid ounces (850ml).
Engine crankcase oil capacity (with oil filter change)
Is about 1 U.S. quart (946ml).

DO NOT MIX OIL WITH THE GASOLINE.

DANGER!
GASOLINE IS EXTREMELY FLAMMABLE AND
ITS VAPORS ARE EXPLOSIVE. DO NOT PERMIT
SMOKING, OPEN FLAME, SPARKS OR ANY
SOURCE OF HEAT IN THE VICINITY WHILE HANDLING GASOLINE. AVOID SPILLAGE OF GASOLINE ON A HOT ENGINE. THERE MUST BE NO
LEAKAGE OF GASOLINE INTO THE RV GENERATOR COMPARTMENT.
GASEOUS FUEL SYSTEMS:
Some RV generator models may be equipped with an
LP or natural gas fuel system. The use of such gaseous
fuels may result In a slight power loss as compared to
gasoline. However, that disadvantage Is usually compensated for by the many advantages offered by such
fuels. Some of these advantages are:

0
0
0
0
0
0

A low residue content which results In minimum
carbon formation In the engine.
Reduced sludge buildup In the engine oil.
Reduced burning of valves as compared to gasoline.
No "washdown" of the engine cylinder wall during
cranking and startup.
Excellent anti-knock qualities.
A nearly homogenous mixture In the engine cylinder.
Fuel can be stored for long periods without breakdown.

DANGER!
GASEOUS FUELS ARE HIGHLY VOLATILE AND
THEIR VAPORS ARE EXPLOSIVE. LP GAS IS
HEAVIER THAN AIR AND WILL SETTLE IN LOW
AREAS. NATURAL GAS IS LIGHTER THAN AIR
AND WILL ACCUMULATE IN HIGH AREAS. EVEN
THE SLIGHTEST SPARK CAN IGNITE THESE
FUELS AND CAUSE AN EXPLOSION. THE USE
OF LEAK DETECTORS IS RECOMMENDED
WHEN GASEOUS FUELS ARE USED. ALL
CODES, STANDARDS AND REGULATIONS PERTAINING TO THE INSTALLATION AND USE OF
GASEOUS FUELS MUST BE COMPLIED WITH.

Page 2.1-2

Change engine oil and the oil filter after the first eight
(8) hours of operation. Thereafter, change engine oil and
oil filter every 50 operating hours.

NOTE: Additional Information on the engine oil
system can be found In Part 5 of this manual,
"Engine 011 and Cooling System".

Storage Instructions
PREPARATION FOR STORAGE:
The engine should be started at least once every
seven (7) days and allowed to run for at least thirty (30)
minutes. If this cannot be done and the engine Is to
remain unused longer than thirty (30) days, It must be
prepared for storage. To prepare the unit for storage,
proceed as follows:

1. Start the engine and let It warm up.
2. After engine Is thoroughly warmed up, shut It down.

NOTE: If the unit Is equipped with a gasoline fuel
system and GASOHOL was used as a fuel, turn off
the supply of fuel to the engine and let It run out of
gas.
3. While engine Is still warm from running, completely
drain the oil. Then, refill with the recommended oil. See
"Recommended Engine 011•.
4. Attach a tag to the engine Indicating the viscosity and
classification of the oil fn the crankcase.
5. Remove the spark plug and pour about one (1) ounce
(15ml) of clean, fresh engine oil Into the spark plug
threaded opening. Crank the engine several Urnes to
distribute the oil, then Install and tighten the spark plug.
6. Remove the battery and store It In a cool, dry room on
a wooden board. Never store the battery on any concrete
or wood floor.
7. Clean and wipe the generator exterior surfaces.

RETURN TO SERVICE AFTER STORAGE:
To return the unit to service after storage, proceed as
follows:
1. Verify that the correct oil Is In the engine crankcase by
checking the tag on the engine (see "Recommended
Engine 011".) If necessary, drain oil and refill with the
recommended oil.

•

Section 2.1- GENERAL INFORMATION
2. Check the battery. Fill all battery cells to the proper
level with distilled water. DO NOT USE TAP WATER IN
THE BATTERY. If necessary, recharge the battery to a
100 percent state of charge or replace It, If defective.
3. Tum OFF all electrical loads. Start the engine at noload and let lt.warm up.
4. Apply electrical looads to at least 50% of the unit's
rated capacity.
5. When engine Is thoroughly warmed up, tum off or
disconnect all electrical loads. Then, shut the engine
down.
THE UNIT IS NOW READY FOR SERVICE.

Engine Tuneup
The following procedure may be used as a minor
tuneup. On completion of the procedure, the engine
should run properly.lf It does not run properly, additional
checks and repairs are required.

•

1. Service and repair engine air cleaners, as necessary.
2. Check engine oil level and condition of oil. Add or
change oil as required.
3. Remove shrouding and clean away dirt from the engine cylinder head and cooling fins.
·
4. Check fuel filters and clean or replace as necessary.
5. Replace the spark plug with a Champion RC12YC (or
equivalent) plug.
a. Set spark plug gap to 0.030 Inch (0.76mm).
b. Install new plug and tighten to 13 foot-pounds (1.8
N-m)•
c. If a torque wrench Is not available, tighten spark
plug as tight as possible with fingers and then
(1) If plug Is RE-USED, tighten about 1/4 turn more
wfth a wrench.
(2) H plug Is NEW, tighten It about 1/2 turn more with
a wrench.
6. Check that wiring Is free of breaks, abrasions and are
properly routed.
1. Check for spark as outlined In "Ignition" section of Part
6 of this manual.
8. Run engine, adjust carburetor If necessary and check
operation•

•
Page 2.1-3

Section 2.1- GENERAL INFORMATION
Exploded View of Engine Long Block

2
3
4
5
6
7
8
10
11
12
13
14
15
16
17
18
19
21
22
23
24
25
26
27
28
29
30

1
1
2
1
1
2
1
1
1
1
2
1
4
4
3
1
1
1
1
1
1
1
4
1
6
1
2

Piston Pin
Piston Ring Set (STD)
114• Pipe Plug
Breather Cover
Piston
Piston Pin Retainer
Crankshaft & Gear Assembly
011 Breather Separator
Crankcase Assembly
Sleeve Bearing
Crankshaft Oil Seal
Breather Baffle Cup
M6 Screw
Lockwasher
Dowel Sleeve
Camshaft Assembky
Crank Case Flange Gasket
Cylinder Head Gasket
011 Pressure Spring Retainer
Oil Pressure sering
011 Pressure Relief alve Ball
Thread Forming Bolt
M6 Screw & Lockwasher
011 Filter Adapter
MB-1.25 Capscrew
Oil Pressure Switch
Valve Spring Retainer

NOTE 1:- Item 36 Includes valve seats and guides.
NOTE 2:- Use a Champion RC12YC (or equlvakent)
spark plug with gap set to 0.030 Inch (0.76mm).

50
5
49

Page 2.1-4

32
33
34
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60

1
1
2
1
1
1
2
2
1
1
2
2
2
1
5
1
2
2
1
1
2
1
1
2
2
1
1
1

Dowel Pin
Inner 011 Pump Rotor
Connecting Rod Bolt
Cylinder Head (see NOTE 1)
Exhaust Valve
Intake Valve
Push Rod
Tappet
011 Pickup Screen
Rocker Cover Gasket
Pivot Ball Stud
Rocker Arm
Rocker Arm Nut
Puch Rod Guide Plate
Head Bolt
Rocker Cover
Breather Gasket
Bolt
Outer 011 Pump Rotor
011 Sump Assembly
Valve Spring Wear Washer
Intake Valve Seal
011 Temperature Switch
M3 Screw
M3 Lockwasher
Spark Plug (see NOTE 2)
Oil Filter Adapter Gasket
1/4• NPT Pipe Plug

.r'\

------------------------------------------------------~

Section 2.2- VALVE TRAIN

•

Valve Train Components
Valve train components are listed below and shown In
Rgure 1, below.
ITEM
1
2

3
4
5
6
7
8
9

10
11

QTY

DESCRIPTION

2
2
2
2
2
1
2
2
2
1
1

Pus Rod
Rocker Arm
Pivot Ball Stud
Rocker Arm Jam Nut
Push Rod Guide Plate
Valve Spring
Valve Spring Retainer
Valve Sprln\rWasher
Exhaust alva
Intake Valve

Ta~pet

2. Loosen the rocker arm jam nuts on the pivot ball studs.
Then, loosen the pivot ball studs. Remove the two pivot
ball studs, the rocker arms and the jam nuts. Also remove
the push rod guide plate.

NOTE: Keep the Intake valve and exhaust valve
parts separated. Intake and exhaust parts are Identical. However, once a wear pattern has been established on these parts their fit will be different.
Figure 3. Roc er Arm, Push Rod & Guide Plate

Figure 1. Valve Train Components

3. Remove the push rods.
4. Remove the cylinder head bolts, then remove the
cylinder head and head gaskeL

•

NOTE: Replace the head gasket every time the head
Is removed. The new head gasket must be free of
nicks and scratches as these could cause leakage.

CYLINDER

HEAD

CRANKCASE

Valve Components Removal
1. The ROCKER ARM COVER Is retained by four M6-1.00
x 12mm screws and lockwashers. Remove the four
screws and lockwashers, then remove the ROCKER ARM
COVER and Its gaskeL

NOTE: Replace the ROCKER ARM COVER GASKET
each time the COVER Is removed, to ensure proper
sealing.

CYUNDER

HEAD

BOLTS

HEAD
GASKET

DANGER!
ALWAYS WEAR SAFETY GLASSES WHEN RE·
MOVING THE VALVE SPRINGS.

•

5. See Figure 5, next page. Hold the valve with your
fingers while compressing the spring with your thumb,
then proceed as follows:

Page 2.2-1

Section 2.2- VALVE TRAIN
Valve Components Removal (Continued)
a. While the spring Is compressed, slide the larger hole
of the valve spring retainer toward the valve stem.
b. With the larger spring retainer hole around the valve
stem, release the spring.
c. Remove the valve spring retainer, the spring and the
spring washer.
Figure 5. Removal of Valve Spring

VALVE MARGIN (GN220)
DESIGN MARGIN: 0.034-o.044 Inch (0.87-1.13mm)
WEAR LIMIT: 0.020 Inch (0.50mm) Maximum
INTAKE VALVE STEM DIAMETER (GN190)
DESIGN DIAMETER: 0.215-Q.216 Inch (5.465-5.480mm)
WEAR LIMIT: 0.214 Inch (5.435mm) Minimum
INTAKE VALVE STEM DIAMETER (GN220)
DESIGN DIAMETER: 0.274-o.275 Inch (6.965-6.980mm)
WEAR LIMIT: 0.273 Inch (6.934mm) Minimum
EXHAUST VALVE STEM DIAMETER (GN190)
DESIGN DIAMETER: 0.214-o.215 Inch (5.445-5.460mm)
WEAR LIMIT: 0.2131nch (5.415mm) Minimum
EXHAUST VALVE STEM DIAMETER (GN220)
DESIGN DIAMETER: 0.273-Q.274 Inch (6.945-6.960mm)
WEAR LIMIT: 0.272 Inch (6.909mm) Minimum

NOTE: Design sizes and wear limits of valve train
components can also be found In Part 9 of this
Manual ("SPECIFICATIONS & CHARTS").
VALVE SEATS:
6. Remove the Intake and exhaust valves.
7. Clean all parts. Remove carbon from valve heads and
stems.
8. Inspect the valves and valve seats. Service parts as
outlined under •valve Service•.

F.gure 7.

Valve seats are NOT
replaceable. If burned
or pitted, seats can be
reground. Grind seats
at a 45" angle and to a
width of 0.039 Inch
(1.0mm).

Valve Service
VALVES:
Replace valves If they
are damaged, distorted
or If the margin Is ground
to less than 0.039 Inch
(1.0mm). If the valves
are In useable condition,
use a valve grinder to
grind the faces to a 45"
angle. Check valve stem
diameter.
After the valves have
been reconditioned, they
should be lapped with a
suitable lapping tool and
valve lapping compound.

F1gure 6.

NOTE: Proper lapping of valves and valve seats will
remove grinding marks and ensure a good seal
between the valve and Its seat. Be sure to clean
lapping compound from the valve seats and faces.
VALVE MARGIN (GN190)
DESIGN MARGIN: 0.058-Q.OGO inch (1.48-1.52mm)
WEAR LIMIT: 0.039 Inch (0.98mm) Maximum

Page 2.2-2

VALVE SEAT WIDTH (GN190 & GN220)
DESIGN WIDTH: 0.034-D.044· Inch (0.87-1.13mm)
WEAR LIMIT: 0.064 Inch (1.63mm) Maximum

VALVE

~UIDES:

Valve guides are permanently Installed In the cylinder
head and cannot be replaced. If the guides become worn
beyond the wear limit, they can be reamed to accomodate a 0.020 Inch (0.50mm) oversize valve stem. Use a
straight shank hand reamer or a low speed drill press to
ream valve guides.
VALVE GUIDES (GN190)
DESIGN DIAMETER: 0.216-Q.2171nch (5.505-5.520mm)
WEAR LIMIT: 0.218 Inch (5.54mm) Maximum

VALVE GUIDES (GN220)
DESIGN DIAMETER: 0.237-Q.2364 Inch (6.02-6.005mm)
WEAR LIMIT: 0.238 Inch (6.045mm) Maximum

NOTE: After the valve guides have been oversized,
be sure to recut the valve seats so they will align
with the guides.

~
r
\

Section 2.2- VALVE TRAIN

•

Valve Service (Continued)

1. Lubricate the valve stems and the valve guides with
engine oil.
2. Install the Intake and exhaust valves through their
respective valve guides In the cylinder head.
a. The exhaust valve has the smaller head with a
diameter of 1.0531nches (26.75mm).
b. The Intake valve has the larger head, having a
diameter of 1.171 Inches (29.75mm).
c. Valve seat sizes In the cylinder head will match their
respective head sizes.

NOTE: The exhaust valve stem Is also smaller than
that of the Intake valve.
Figure 11. Installation o Intake and Exhaust a ves

VALVE GUIDES
VALVE TAPPETS:
Valve tappets can be
removed during removal of the engine
camshaft. Intake and
exhaust valvG tappets
are Identical. However,
once a wear pattern
has been established
the two tappets should
not be Interchanged.

Figure 9•
.,.---

INTAKE

•

VALVE SPRINGS:

Inspect the valve
springs. Measure the
spring free length.
Also, check the amount
of force required to
compress the spring to
a length of 1.39 Inch
(35.2 mm). Replace any
damaged or defective
spring.

EXHAUST

BE SURE TO LUBRICATE VALVE
GUIOES & STEMSI

3. Install the valve
spring washers, valve
springs and valve
spring retainers over
the valve guides.
a. Hold the valve
with your fingers
and use your
thumbs to compress the spring.
b. When the spring
Is compressed sufficiently, slide the
spring retainer
small opening over
the valve stem.
c. With the smaller
retainer opening
around the valve
stem, release the spring.
4. After both valves have been retained In the cylinder
head, position a new head gasket and Install the cylinder
head.

L-------------1

VALVE SPRING FREE LENGTH
GN190: 1.910 Inch (48.48mm)
GN220: 2.074 Inch (52.69mm)
FORCE REQUIRED TO COMPRESS SPRING
TO 1.39 INCH (35.2MM)
GN190: 14.8-16.2 lbs (6.7-7.4kg)
GN220: 19.8-21.8 lbs (9.0·9.9kg)

•

Valve Components Installation
After the valve train parts have been Inspected and (If
necessary) serviced, Install them as follows:

NOTE: The head gasket Is coated with a special
substance for better sealing. The gasket must be
free of nicks, scratches and other defects for better
sealing.
5. Install cylinder head bolts. Tighten the head bolts In
the sequence shown to the recommended tightness.

Page 2.2-3

Section 2.2- VALVE TRAIN
Valve Components Installation
(Continued)

Figure 15. Pus Rod Installation

TIGHTENING TORQUE
CYLINDER HEAD
GN190: 25 foot-pounds
GN220: 29 foot-pounds
Figure 13. Head Bolts Tightening Sequence

Adjusting Valve Clearance
When adjusting valve clearance, the engine should be
at room temperature and the piston should be attop dead
center (TDC) of Its compression stroke (both valves
closed).

TORQUE SEQUENCE= 1-2-3-4-5
6. Place the push rod guide plate Into position on the
head. Then, Install the rocker arm and the pivot ball
stud. The rocker arm jam nut must be on far enough to
hold the guide plate In position.

NOTE: Do NOT adJust valve clearance at this time.
This will be done later.

VALVE CLEARANCE
GN190 ENGINE
INTAKE VALVE: 0.001-0.0031nch (0.0~.07mm)
EXHAUST VALVE: 0.001-0.0031nch (0.0~.07mm)
VALVE CLEARANCE
GN220 ENGINE
INTAKE VALVE: 0.001-0.00221nch (0.03-0.056mm)
EXHAUST VALVE: 0.0018-0.0031nch (0.046-0.07mm)
Adjust the valve clearance as follows:
1. Rotate the crankshaft until the piston Is at top dead
center (TDC) of Its compression stroke. Both valves
should be closed.
2. Loosen the rocker arm jam nuL
3. Use an allen wrench to turn the pivot ball stud while
checking the clearance between the rocker arm and the
valve stem with a feeler gauge.
Figure 16. Adjusting Valve Clearance

7. Install the push rod with either end against the tap peL
a. Place the push rod between the guide plate tabs.
b. Place the rocker arm socket onto end of push rod.
c. Alignment Is correct when push rod ball rests In the
rocker arm socket.

NOTE: The pivot ball stud will be tightened when
the valve clearance Is adjusted. After valve clearance has been adjusted, the rocker arm cover will
be Installed.

Page 2.2-4

LOOSEN
JAM NUT

''-----·

•

Section 2.2- VALVE TRAIN
4. When valve clearance Is correct, hold the pivot ball
stud with the allen wrench while tightening the rocker
arm Jam nut with a crew's foot. Tighten the Jam nut to the
specified torque. After tightening the Jam nut, recheck
the valve clearance to make sure It did not change.

Rocker Arm Cover Installation
Place a new rocker arm cover gasket Into place. Then,
Install the rocker arm cover. Finally, retain the cover with
MG-1.00 x 12mm screws.
Figure 18. Rocker rm Cover Installation

JAM NUT TIGHTENING TORQUE
GN190: 75 Inch-pounds
GN220: 6.3 foot-pounds

Ttghten jam nut to
85-85 inch-pounds
(7-10 N-m) •

•

•
Page 2.2-5

Section 2.2- VALVE TRAIN

Page 2.2-6

•

Section 2.3- PISTON, RINGS, CONNECTING ROD
CHECK FOR PISTON WEAR:

Oversize Piston & Rings

The piston is slightly elliptical. It's smaller diameter is in line with the wrist pin boss. It's larger
diameter is 90° from the wrist pin boss.
NOTE: An assembly mark Is provided on the piston.
This mark should face the flywheel end of the
crankshaft {3:00 position) during reassembly.

Worn or scored cylinders may be rebored to 0.010
(0.25mm) or 0.020 (O.SOmm) oversize. Pistons and piston rings of matching oversize are available to fit the
rebored cylinder.
Figure 1. Piston, Rings and Connecting Rod

Figure 3. E/1/ptlcal Shape of Piston

CONNECTING
ROD

2.753-2.7541n.
69.93!Hi9-959mm.

~.Sin.
35.5-40.5mm

CAP

BOLT

---i

To check the piston for wear, proceed as follows:

•

Prior to Removal
Before removing pistons, rings and connecting rod,
clean all carbon from the cylinder bore. Carbon buildup
In the cylinder bore can cause ring breakage during
piston removal.

1. Minor Diameter:- At a position directly In line with the
wrist pin hole, measure from
top of piston down to a distance of 1.4-1.6 Inches (35.540.5mm). This Is the •mlnorM
diameter. Measure at this point
to check for wear.

Removal
Remove the connecting rod CAP BOLTS and the connecting rod CAP. Then, push the piston and connecting
rod out through top of cylinder.

Piston

PISTON MINOR DIAMETER (GN190 & GN220)
DESIGN DIAMETER: 2.747-2.748 Inch (69.78969.809mm)
WEAR LIMIT: 2.745 Inch (69.739mm) Mlni~um

REMOVE FROM CONNECTING ROD:

NOTE: An oil hole In the wrist pin area of the piston
helps distribute oil to assist In cooling. The oil hole
also provides an assist In removing the wrist pin
snap ring.
To remove the piston from
the connecting rod, proceed
as follows:

•

1. Move the snap ring around
until Its protruding end Is
aligned with the notched out
oil hole. Use needle nose pliers to turn the snap ring and
pull It toward you.
2. With one snap ring removed, slide the wrist pin
out of the piston boss. This
will separate the piston from
the connecting .rod.

2. Major Diameter:- At a point
90" from the wrist pin bore,
measure down 1.4-1.6 Inches
(35.5-40.5mm). This is the
•major• diameter. Measure at
this point to check for piston
wear. Replace the piston If wear
limits are exceeded.

gure2.

,,
\.)'..

Figure 5.

3. Check wrist Pin for Looseness:- A rough check for
wear In the wrist pin, wrist pin bore in the piston, or wrist
pin bore In the connecting rod Is to check for looseness
or play with the piston assembled to the rod. Looseness
or play Indicates a worn wrist pin, or a worn bore In the
piston or connecting rod.

NOTE: Always apply engine o/1 to wrist pin and Its
bores during lnstalfatlon. Wrist pin fit Is very close.

Page 2.3-1

Section 2.3- PISTON, RINGS, CONNECTING ROD
Piston (Continued)

Piston Rings

CHECK PISTON FOR WEAR (CONT'D):

GENERAL:

4. Check Wrist Pin for Wear:- Measure the outside diameter of the wrist pin. Also measure the Inside diameter of
the wrist pin bora In the piston and In the connecting rod.
Also check wrist pin length. Replace any component that
Is worn excessively.

The following rules pertaining to piston rings must
always be complied with:

WRIST PIN OUTSIDE DIAMETER (GN190 & GN220)
DESIGN DIAMETER: 0.708-0.7091nch (17.989·
18.000mm)
WEAR LIMIT: 0.7071nch (17.969mm) Minimum
WRIST PIN LENGTH (GN190 & GN220)
DESIGN LENGTH: 2.196-2.213 Inch (55.8·56.2mm)
WEAR LIMIT: 2.193lnch (55.7mm) Minimum
WRIST PIN BORE IN PISTON (GN190 & GN220)
DESIGN DIAMETER: 0.708-D.709 Inch (18.000·
18.011mm)
WEAR LIMIT: 0.710 Inch (18.026mm) Maximum
CONNECTING ROD SMALL END J.D. (GN190 & GN220)
DESIGN DIAMETER: 0.709-D.710 Inch (18.02·18.03mm)
WEAR LIMIT: 0.7111nch (18.05mm) Maximum

0
0
0
0

RING DESCRIPTION:
A piston ring SET consists of (a) a top compression
ring, (b) a second compression ring, and (c) an oil ring
assembly. When Installing rings, pay close attention to
the following:

0
0
0

5. Ring to Groove Side Clearance:- Clean carbon from
piston ring groo\' Js. Install new rings. Use a feeler gauge
to measure the side clearance between the rings and ring
grooves. If ring-to-groove side clearance exceeds the
stated limits, replace the piston.
RING TO GROOVE SIDE CLEARANCE (GN190 &
GN220)
0.0004-0.00141nch (0.012-D.034mm)

Always replace piston rings In sets.
When removing rings, use a ring expander to prevent breakage. Do not spread the rings too far or they
will break.
When Installing the piston Into the cylinder, use a
ring compressor. This will prevent ring brteakage
and/or cylinder damage.
When Installing new rings, deglaze the cylinder wall
with a commercially available deglazlng tool.

The OIL RING Is a 3-plece assembly which consists
of two oil ralls and an oil spacer ring. 011 ralls have
a rounded face and can be Installed with either side
up.
The second compression ring has an Inside chamfer
which must face UP when Installing the ring.
The top compression ring has a barrel-shaped face
and can be Installed with either side up.

TOP COMPRESSION RING
l....lill~¥ EITHER SIDE UP

2ND COMPRESSION RING
""'""-'~If' CHAMFER FACES UP

e Clearance
OIL CONTROL RING
EITHER SIDE UP
1ST COMPRESSION

CHECKING PISTON RING END GAP:

2ND COMPRESSION
RING

To check piston rings end gap, proceed as follows
(see Figure 8):
1. Locate a point Inside the cylinder that Is 2.75 Inches
(70mm) down from top of cylinder. This Is approximately
half-way down.
2. Place the ring Into the cylinder. Use the piston to push
the ring squarely Into the cylinder to the proper depth.
3. Use a feeler gauge to measure the ring end gap. If end
gap Is excessive, rebore the cylinder to take oversize
parts.
TOP RING END GAP (GN190 & GN220)
DESIGN GAP: 0.005-D.0161nch (0.15-D.40mm)
WEAR LIMIT: 0.024 inch (0.60mm) Maximum

Page 2.3·2

Section 2.3- PISTON, RINGS, CONNECTING ROD

•

INSTALLATION:
SECOND RING END GAP )GN190 & GN220)
DESIGN GAP: 0.006-0.0161nch (0.15-0.40mm)
WEAR LIMIT: 0.024 Inch (0.60mm) Maximum
OIL RING END GAP (GN190 & GN220)
DESIGN GAP: 0.015-0.055 Inch (0.38·1.40mm)
WEAR LIMIT: 0.062lnch (1.60mm) Maximum
Figure B. Ring End Gap

Coat the cylinder walls with engine oil, as well as the
crank throw, connecting rod bearing and connecting rod
cap bearing. Then, Install the rod and piston assembly
as follows:
1. Use a ring compressor to compress the rings Into the
~lston rlnt grooves. MAKE SURE ALL RINGS ARE
ULLY CO PRESSED INTO THEIR GROOVES.
2. Guide the connecting rod into the cylinder, with as
sembly mark on piston toward the flywheel side of engine.
3. When the ring compressor contacts top of cylinder,
use a wood hammer handle to gently tap the piston down
Into the cylinder.
4. Check that the connecting rod's large diameter bearIng Is coated with oil, as well as the crank throw and the
connecting rod cap.
5. Guide the large end of the connecting rod onto the
crankshaft. Install the connecting rod cap. The match
mark on the cap must be aligned with an Identical mark
on the rod (t=lgure 10).
6. Install the connecting rod cap bolts and tighten to. the
proper torque.
~

TIGHTENING TORQUE
CONNECTING ROD CAP BOLTS (GN190 & GN220)
10 foot-pounds (1.36 N-m)

•

Connecting Rod

~--------~g-u~-8~9~.--------~

The connecting rod Is manufactured of die cast aluminum. Alignment marks are
provided on the rod and on the
connecting rod cap. Be sure to
align these marks when assembling the rod to the crankshaft. Connecting rod bolts
are of the •washerless" type.
The connecting rod and the
connecting rod cap are a
matched set and must be replaced as a matched set.

NOTE: The connecting rod can be Installed In either
direction. That Is, the cap marks on the rod and cap
may face toward the Installer or away from the
/nslaller. The only requirement Is that the assembly
mark on top of piston be toward the flywheel side
of engine.
gure 10. Mate

arks on Rod an

Cap

MATCH MARKS

Assembly and Installation
ASSEMBLY:

•

Use ~.ring expander when Installing rings Into the
piston ring grooves. Install the OIL RING ASSEMBLY
first. Then, Install the second compression ring with its
Inside chamfer facing up. Finally, Install the top compression ring.
When assembling the piston, connecting rod and wrist
pin, the assembly marks on the piston must be toward
the flywheel side of the engine.
Coat the wrist pin, wrist pin bore In piston, and wrist
pin bore In the rod with engine oil. Install one snap ring
Into the piston's wrist pin bore. Then, assemble the
piston to the rod. Slide the wrist pin through one piston
bore, through the rod bore, and through the second
piston bore until It contacts the snap ring. Then, Install
the second snap ring Into the piston bore.

Cylinder Service
INSPECTION:
Check the cylinder for dirty, broken or cracked fins.
Also look for worn or scored bearings, or a scored
cylinder wall. Check the cylinder head mounting surface
for warpage. If the head is warped, it must be replaced.
If the cylinder bore is worn (as evidenced by excessive
ring end gap), the cylinder should be replaced or rebored
to 0.010 or 0.020 (0.25 or O.SOmm) oversize.
After reboring the cylinder to a specific oversize, Install an identically oversize piston along with Identically
oversized rings.

Page 2.3-3

Section 2.3- PISTON, RINGS, CONNECTING ROD
CylinderServke(ConHnued)
REBORING THE CYUNDER:
Always resize the cylinder bore to EXACTLY 0.010
Inch or 0.020 Inch (0.25 or 0.50mm) over the standard
cylinder dimensions. If this Is done accurately, the service oversize ring and piston will fit and correct clearances will be maintained.
STANDARD CYLINDER BORE DIAMETER
MINIMUM: 2.7560 Inches (70.000mm)
MAXIMUM: 2.7570 Inches (70.025mm)
To rebore the cylinder, use a commercial hone of
suitable size chucked In a drill press having a spindle
speed of about _600 rpm. Use the stones and lubrication
recommended by the hone manufacturer to produce the
proper cylinder bore finish. Proceed as follows:
1. Start with coarse stones. Center the cylinder under the
drill press spindle. Lower the hone so that the lowest end
of the stone contacts the lowest point In the cylinder
bore.
2. Begin honing at bottom of cylinder. Move the hone up
or down at about 50 strokes per minute, to avoid cutting
ridges In the cylinder wall. Every fourth or fifth stroke,
move the hone far enough to extend It one (1) Inch
beyond the top and bottom of the cylinder bore.
3. Every 30 or 40 strokes, check the bore for size and
straightness. H stones collect metal, clean them with a
wire brush.
4. Hone with coarse stones until the cylinder bore Is
within 0.002 Inch (0.05mm) of the desired finish size.
Then, replace the coarse stones with burnishing stones
and continue until bore Is within 0.00051nch (0.01mm) of
the desired size.
5. Install finishing stones and polish the cylinder to Its
final size.
6. Clean the cylinder with soap and water. Dry thoroughly.
7. Replace the piston and rings with parts of correct
oversize.

Page 2.3-4

Section 2.4- CRANKSHAFT AND CAMSHAFT

•

General

Figure 2. Camshaft Removal

Prior to removal of the crankcase cover, gain access
to the engine and generator by removing surrounding
sheet metal as required. See Section 1.6.

Crankcase Cover Removal
Before attempting to remove the crankcase cover,
remove rust, paint and burrs from the power takeoff
(PTO) end of the crankshaft. This will reduce the possibility of damaging the oil seal In the crankcase cover or
the bearing during cover removal.
To remove the crankcase cover, proceed as follows:
1. Drain oil from the crankcase.
2. Remove the engine cylinder head, push rods and push
rod guide plate. See Section 2.2.
3. Remove all bolts that retain the crankcase cover to the
crankcase.
4. Remove the crankcase cover. If necessary, tap lightly
with a soft hammer on alternate sides of the cover.

Figure 3. Cranksha

Figure 1. Crankcase Cover Removal

.... _

•
Camshaft Removal
See Figure 2. Remove the camshaft as follows:
1. Tip the engine over onto the flywheel end of the
crankshaft. Support the engine to prevent end of crankshaft from resting on the workbench.
2. Reach In with two fingers and hold the tappets up so
they are clear of the camshaft lobes. Then, remove the
camshaft.
3. Remove the two tappets.
4. Remove the outer and Inner oil pump rotors.

Camshaft Inspection
Carefully Inspect the entire camshaft for wear, nicks,
damage. All areas Indicated In Figure 4 should be
checked for wear.
Figure 4. Points to Check on Camshaft

Crankshaft Removal
See Figure 3. To remove the crankshaft, proceed as
follows:

•

1. The engine flywheel must be removed before the
crankshaft can be removed.
2. The piston and connecting rod must be removed.
3. Remove the crankshaft by pulling It straight out of the
crankcase.

1. Check spring pln11.
2. Camshaft gear.
3. CompNaalon releue parta.
4. Main beerlng (flywheel end).
5. Main bearing (PTO end).
a. Cam lobea.

Page 2.4-1

Section 2.4- CRANKSHAFT AND CAMSHAFT
Camshaft Inspection (Continued)
The following should be measured carefully to check
for wear:

CRANKPIN OUTSIDE DIAMETER
DESIGN DIAMETER: 1.180·1.1811NCH (29.99·30.01MM)
WEAR LIMIT: 1.179 inch (29.96mm) Minimum

MAIN CAMSHAFT BEARING DIAMETER
~LYWHEEL END)
DESIGN DIAMETE : 1.022-1.023 Inch (25.96-25.98mm)
WEAR LIMIT: 1.020 Inch (25.91mm) Minimum

CRANKSHAFT BEARING JOURNAL (FLYWHEEL END)
DESIGN DIAMETER: 1.102·1.103 Inch (28.00028.012mm)
WEAR LIMIT: 1.100 inch (27.95mm) Minimum

MAIN CAMSHAFT BEARING DIAMETER
f;TO END) GN-190 ONLY
DESIGN DIAM ER: 1.022-1.0231nch (25.96·25.98mm)
WEAR LIMIT: 1.020 Inch (25.91mm) Minimum

CRANKSHAFT BEARING JOURNAL ~TO END)
DESIGN DIAMETER: 1.102·1.103 inc (28.00028.012mm)
WEAR LIMIT: 1.1861nch (27.95mm) Minimum

MAIN CAMSHAFT BEARING DIAMETER
(PTO END) GN-220 ONLY
DESIGN DIAMETER: 1.297·1.298 Inch (32.96·32.98mm)
WEAR LIMIT: 1.2951nch (32.89mm) Minimum

Figure 5. Points to Check on Crankshaft

CAMSHAFT BEARING BORE IN CRANKCASE
DESIGN DIAMETER: 1.024-1.0251nch (26.00·26.03mm)
WEAR LIMIT: 1.026 Inch (26.06mm) M.axlmum
CAMSHAFT BEARING BORE IN CRANKCASE COVER
DESIGN DIAMETER: 1.299-1.300 Inch (33.0Q-33.03mm)
WEAR LIMIT: 1.302 Inch (33.06mm) Maximum
CAM LIFT
DESIGN LIFT: 0.210.0.212 Inch (5.34·5.38mm)
WEAR LIMIT: 0.206 Inch (5.24mm) Minimum

1. Cheek kaywaya.
2. Crankshaft gear.
3. 011 paaaage.
4. Journal (ftywhael end).
5. Journal (PTO end).
6. Crankpln.
7. Threaded ende.

Crankshaft Inspection:
CRANKSHAFT PROPER:
Use a commercial solvent to clean the crankshaft.
After cleaning, Inspect the crankshaft as follows:

0
0
0

Inspect keyways In crankshaft, make sure they are
not worn or spread. Remove burrs from edges of
keyway, to prevent scratching the bearing.
Inspect timing gear teeth for chipping or cracking. If
the timing gear Is damaged, the crankshaft assembly
must be replaced.
Inspect the crankpln for damage, nicks, scratches,
etc. Small nicks and scratches may be polished out
using fine emery cloth. ALL EMERY RESIDUE MUST
BE REMOVED. Use a solvent (such as kerosene) to
remove emery residue.
Carefully measure the outside diameter (O.D.) of the
crankpln, crankshaft journal at flywheel end, and
crankshaft journal at PTO end. Replace the crankshaft If It Is worn smaller than the stated limits.

NOTE: DO NOT regrind the crankpln to any smaller
diameter. Undersize connecting rods are NOT
available for the GN-190 or GN-220 engines.

Inspect oil passage. Use a length of wire to make
sure It Is open. Inspect threaded ends of crankshaft.

Page 2.4-2

CRANKSHAFT SLEEVE BEARING:
A sleeve bearing (Figure 6) Is pressed Into the crankshaft bore of the crankcase. A bearing Is NOT provided
for the crankshaft bore In the crankcase cover.
Inspect the sleeve bearing In the crankcase for damage. Measure the Inside diameter (J.D.) of the sleeve
bearing. Replace any sleeve bearing that Is worn excessively. Press out the old bearing, press a new bearing
Into place.
CRANKSHAFT SLEEVE BEARING
DESIGN DIAMETER: 1.104-1.106 Inch (28.04428.099mm)
WEAR LIMIT: 1.107 inch (28.129mm) Maximum
Check the crankshaft bearing bore In the crankcase
cover. If limits are exceeded, replace the crankcase
cover.
CRANKSHAFT BEARING BORE IN CRANKCASE
COVER
DESIGN DIAMETER: 1.104-1.105 inch (28.040·
28.065mm)
WEAR LIMIT: 1.106 inch (28.092mm) Maximum

•

Section 2.4- CRANKSHAFT AND CAMSHAFT
Figure 6.

/eeve Bearing In Crankcase

Figure B. Compression Release Meehan sm on Camshaft
CAMSHAFT

GEAR

SLEEVE

.-~~
OIL SEAL

Figure 7. Bearing Bore In Crankcase Cover

Compression relief lift can also
be measured at the valve rocker arms,
using a dial Indicator•

•
Compression Release Mechanism
A mechanical compression release Is provided on the
camshaft. See Agure 8. A PIN extends over the cam lobe.
This PIN pushes on the tappet, to lift the valve and relieve
compression for easier cranking. When the engine
starts, centrifugal force moves the FLYWEIGHT outward
against SPRING force. The PIN will then drop back and
allow the engine to run at full compression.
Measure the amount of compression release lift at the
tappet (Agure 9).
COMPRESSION RELEASE LIFT FOR GN-190 ENGINE
(MEASURED AT TAPPET)
DESIGN LIFT: 0.027-Q.OSS Inch (0.7D-1.40mm)
WEAR LIMIT: 0.023 Inch (0.60mm) Minimum

•

COMPRESSION RELEASE LIFT FOR GN-220 ENGINE
(MEASURED AT TAPPET)
DESI,GN LIFT: 0.020-Q.047 Inch (0.5D-1.20mm)
WEAR LIMIT: 0.0161nch (0.406mm) Minimum

Installing the Crankshaft
Before Installing the crankshaft, lubricate all bearing
surfaces with engine oil. Use oil seal protectors, to prevent damage to seals during Installation. Install the
crankshaft as follows:
1. Lubricate all bearing surfaces with engine oil.
2. Install the valve tappets.
3. Support both ends of the crankshaft and carefully
Install Into the crankcase.
4. Rotate the crankshaft until the timing mark (Figure
10) Is toward the cam gear side of the crankcase.

Installing the Camshaft
Apply engine oil to the camshaft main bearing and to
bearing bore In crankcase. Carefully Install the camshaft
Into the crankcase camshaft bore.
Hold the tappets out of the way during Installation.
Align timing mark on camshaft gear with timing mark on
crankshaft gear (piston will be at top dead center). See
Figure 11.

Page 2.4-3

Section 2.4- CRANKSHAFT AND CAMSHAFT
Installing the Camshaft (Continued)
NOTE: For Installation of the oil pump assembly,
oil pickup assembly and crankcase cover, see Part
5 "ENGINE OIL & COOUNG SYSTEM".
Figure 10. Timing Mark on Crankshaft Gear

TIMING
MARK
CAMSHAFT
GEAR

Page 2.4-4

•
Part 3

GASOLINE
FUEL
SYSTEM

•

COMPUTER
CONTROLLED
VARIABLE
SPEED RV
GENERATORS
Series NP-30G and NP-40G

SECTION
3:1
3.2
3.3
3.4
3.5
3.6

TITLE
INTRODUCTION TO FUEL SYSTEM
AIR CLEANER & AIR INTAKE
FILTEA & FUEL PUMP
CARBURETOR
AUTOMATIC CHOKE
SPEED CONTROL SYSTEM

Section 3.1-INTRODUCTION TO FUEL SYSTEM

•

General
Recreational vehicle generators equipped with a gasoline fuel system are usually Installed so that they share
the fuel supply tank with the vehicle engine. When this
Is done, the generator Installer must never tee off the
vehicle fuel supply line to deliver fuel to the generator.
When the generator fuel supply line Is teed off the
vehicle's fuel supply line, the more powerful vehicle
engine's fuel pump will starve the generator when both
are running. In addition, when the vehicle engine Is not
. running the generator fuel pump will draw all of the
gasoline from the vehicle engine line or even from the
vehicle engine carburetor. This will result In hard starting
of the vehicle engine.
One method of sharing the same fuel supply tank Is to
Install a special fitting at the tank outlet so that two fuel
dip tubes can be fitted In the tank (Figure 1). Another
method Is to Install a new outlet In the tank. If the tank
has an unused outlet, It can be used.
A second fuel dip tube can be Installed In the original
tank outlet If the tank outlet Is large enough to accommodate two dip tubes. The required fittings can be made at
a machine shop. To Install a second fuel outlet on the
tank means removing the tank to braze or weld a new
fitting Into place.

DANGER!
ATTEMPTING TO WELD OR BRAZE ON A FUEL
TANK, EMPTY OR NOT, IS EXTREMELY DANGEROUS. FUEL VAPORS IN THE TANK WILL RESULT IN AN EXPLOSION.
The generator's fuel dip tube In the tank should be
shorter than the vehicle engine's dip tube. This will
prevent the generator from consuming the entire fuel
supply.

DANGER!
THE FUEL SYSTEM DESIGNED AND INSTALLED
BY THE GENERATOR MANUFACTURER IS IN
STRICT COMPLIANCE WITH STANDARDS ESTABLISHED BY THE RECREATIONAL VEHICLE
INDUSTRY ASSOCIATION (RVIA). NOTHING
MUST BE DONE DURING MAINTENANCE THAT
WILL RENDER THE SYSTEM IN NON-COMPLIANCE WITH THOSE STANDARDS.
DANGER!
THERE MUST BE NO LEAKAGE OF GASOLINE
OR GASOLINE VAPORS INTO THE VEHICLE. THE
GENERATOR COMPARTMENT MUST BE VAPORTIGHT TO PREVENT ENTRY OF FUEL VAPORS
OR FUMES INTO THE VEHICLE. THE
GENERATOR'S VENTILATION SYSTEM MUST
PROVIDE A FLOW OF AIR THAT WILL EXPEL
ANY FUEL VAPOR ACCUMULATIONS.

not contain more than 10% ethanol and It must be removed from the generator fuel system during storage.
do NOT use fuel containing methanol. If any fuel containing alcohol Is used, the system must be Inspected
more frequently for leakage and other abnormalities.

Figure 1. Sharing a Fuel Supply Tank

FUEL LINE TO
PROPULSION
ENGINE

_l.-..-QIIfl""'"~

Evaporation Control Systems
Federal and state laws have Imposed strict evaporative controls on gasoline fuel systems. The recreational
vehicle Industry has complied with such strict regulations by using specially designed fuel tanks, tank filler
tubes and gas caps. Special canisters are often used to
collect the gasoline vapors rather tl'lan let them escape
into the atmosphere.
Such systems are designed to operate within very
critical pressure ranges. For that reason, the vehicle
manufacturer's fuel supply system design must not be
altered. Service technicians working on the RV generator systems must not do anything that might change the
vehicle fuel system design.

CUSTOMER
CONNECTION

Recommended Fuel

•

Use a high quality UNLEADED gasoline. Leaded REGULAR grade gasoline Is an acceptable substitute•
Do NOT use any fuel containing alcohol, such as
"gasohol" .If gasoline containing alcohol Is used, It must

Page 3.1-1

Section 3.1-INTRODUCTION TO FUEL SYSTEM

Page 3.1-2

•

Section 3.2- AIR CLEANER & AIR INTAKE
Air Intake

Air Cleaner
DESCRIPTION:
The air cleaner assembly consists of (a) an air cleaner
BASE, (b) a PAPER FILTER, and (c) a COVER. See Figure

1.
F. gure 1. Engine Air Cleaner

'\(GENERAC)

BLUE OR
BLACK

Page 8-2

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LEGEND
BATTERY CHAR(;E RECTIF"IER
CIRCUIT BREAKER
CHOKE COIL
COMPUTER CONTROL BOARD
CHOKE HEATER
ENGINE CONTROL BOARD
FUSE, 15A
ruEL PUMP ON GASOLINE
SHUT-orr VALVE ON LIP
GENISTDR
HDJR METER
SWITCH, HIGH TEMPERATURE OIL
(ClOSES ON HIGH TEMPERATURE>
IGNITION COIL
IGNITION MODULE
IGNITION SENSOR
LIGHT, RUN
SWITCH, LOW OIL PRESSURE

STEPPER MOTOR THROTTLE CONTROL
RESISTOR, SOD OHH, SO WATTS
1 OHH, SO WATTS
STARTER CONTACTOR
STARTER MOTOR
SWITCH, START/STOP
SWITCH, F"U£L PUHP PRIME
SPARK PLUG
LUG, BARREL
TERMINAL, CONNECTOR 4 TAB

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CCRV Diagnostic Repair Manual 94468A NP 40G Generac Service

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