61vf Manual

User Manual: 61vf-manual

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O.S. MAX-61VF

INSTRUCTIONS FOR O.S. MAX 61 VF ENGINE

The O.S. MAX-61 VF is a high performance engine that has been

developed expressly for FAI type R/C contest models. It em-

ploys schnuerle scavenging and a rear exhaust port to facilitate

the installation of a tuned silencer system, especially where the

latter

is

to

be

built

into

the

fuselage.

This engine features specially developed ABC type piston/

cylinder construction and a 17 mm O.D. crankshaft of heavy

duty alloy steel in order to provide extra power and durability

and is equipped with an O.S. Type 7D carburettor, specially

designed to give good throttle response.

Modern precision machinery and carefully selected top-quality

materials are employed in the manufacture of this engine to

ensure consistent performance and long life.

SPECIFICATIONS

Displacement

Bore

Stroke

Practical R.P.M.

Power output

Weight

9.95

c.c. (.607 cu.

in.)

24.0

m.m.

(.945

in.)

/

22.0m.m. (.866 in.)

2,000 ~ 17,000 r.p.m.)

1.8 PS (17,000 r.p.m.)

528 g (18.6oz.)

INSTALLATION

Mount the engine securely on rigid hardwood mounts or metal

bearers. For highest performance and safe running, we recom-

mend that the bearers should be as heavy and as rigid as possible.

Make sure the engine bearers are parallel and their mounting

surfaces are in the same plane. Use 4 m.m. or 6—32 steel screws,

such as Alien type, with locknuts, for bolting the engine to the

bearers.

RUNNING-IN ("Breaking-in")

The special ABC type piston/cylinder construction, two ball

bearings, bronze bushed connecting rod, etc., enables this engine

to be operated after a shorter running in period. Preliminary

bench running can be omitted. However, for long life and peak

performance please observe the following procedure:

Install the engine in your model and fly it with a rich needle-

valve setting so that it runs at a fast '4 stroke' for the first two or

three flights. Then readjust the needle valve for a slightly less

rich mixture (i.e. at a reduced speed '2-stroke') for the next four

to six flights.

FUEL

Use a good quality commercial fuel or one of the fuels shown in

the table. "A" is suitable for general use. If higher output is

required, fuels containing 10 to 20% of nitro methane; (e.g."B")

may be used after running in.

Lubricants can be either castor oil or synthetics provided that

they are always of the best quality.

Methanol

Castor Oil

Nitromethane

A

77%

23%

-

B

57%

23%

20%

GLOW PLUG

Since the compatibility of the glow-plug and fuel can have a con-

siderable effect on performance and reliablity, it is suggested

that the user selects the R/C type plug found most suitable after

tests. Recommended O.S. glow-plugs are No. 8 and No. 9.

PROPELLER

Suggested propellers for pattern flying are 11 x 7-8. The

suitability of the prop. depends on the size and weight of the

model and the type of flying. Determine the best size and type

after the engine has been run in. Check the balance of propeller

before fitting it to the engine. Unbalanced propellers cause

vibration and a loss of power.

Wooden propellers are to be preferred. Some nylon propellers

are not strong enough to withstand the high power output of

this engine and a thrown blade can be very dangerous.

SILENCER

As this engine has been designed primarily for use with a tuned

length exhaust silencer system, a conventional silencer is not

supplied. Any of the tuned pipe silencers currently available for

10cc engines may be used by inserting, with the aid of silicone

tubing, a short length of 18—20 mm o.d. aluminium tubing

between the exhaust adaptor (supplied with the engine) and the

tuned silencer. The length of the intermediate tube should be

determined initially in accordance with the instructions issued

with the tuned silencer and then adjusted, as necessary, in accor-

dance with the prop and fuel used, after test flights.

Generally speaking, this intermediate tube length will require to

be between 6 cm (2.4") and 10 cm (4"). Alternatively, a special

O.S. exhaust header pipe is available as an optional extra part.

CARBURETTOR

The special O.S. automatic carburettor described in the attached

instruction sheet is fitted, as standard, to this engine. An exhaust

pressurised fuel system should be used with this carburettor for

best results.

PARTS LIST

27101000

27101602

27102008

27103005

26704007

26705004

27106007

27107004

27108001

29008219

28009002

45010002

Code No.

Description

Crankcase

Front Housing

Crankshaft

Cylinder & Piston Assy. (ABC)

Cylinder Head

Connecting Rod

Piston Pin

Cover Plate

Drive Washer

Woodruff Key

Propeller Washer

Propeller Nut

Code No.

27113004

26714006

26617004

9R731002

27130000

29081004

29081719

27126109

*27126202

*72101300

*72101103

Description

Screw Set

Gasket Set

Piston Pin Retainer

Ball Bearing (Front)

Ball Bearing (Rear)

Carburettor Complete (7D)

Carburettor Retainer

Exhaust Adaptor Complete

Exhaust Header-Pipe Complete

Silicone Tubing Set

Tuned Silencer

Optional parts

The specification is subject to alteration for improvement without notice.

Exhaust Header-Pipe

Silicone Tubing

Tuned Silencer

O.S.

ENGINES

MFG

CO

LTD

6-15 3-chome Imagawa Higashisumiyoshi-ku

Osaka 546, Japan. TEL. Osaka (06) 702-0225

57912