Ktm 50 Sx Users Manual 3211222_BA_50_LC_08_EN.qxp

50 SX JUNIOR to the manual 68bb7498-2100-a0b4-81af-a5b1736c0eab

2015-02-04

: Ktm Ktm-50-Sx-Users-Manual-371000 ktm-50-sx-users-manual-371000 ktm pdf

Open the PDF directly: View PDF .
Page Count: 42

Download
Open PDF In Browser	View PDF

OWNER’S MANUAL 2008
50 SX JUNIOR
50 SX

*3211222en*
3211222en

3211222en

4/2007
FOTO: MITTERBAUER

KTM Group Partner

KTM-Sportmotorcycle AG
A–5230 Mattighofen
www.ktm.com

INTRODUCTION »

Now you own a modern motorcycle that you and your youngster will certainly enjoy, provided that you service and maintain it properly.

Please insert the serial numbers of the motorcycle below

ENGLISH

Chassis number

Engine number

Stamp of dealer

All information contained is without obligation. KTM-Sportmotorcycle AG particularly reserves the right
to modify any equipment, technical specifications, prices, colors, shapes, materials, services, service work,
constructions, equipment and the like so as to adapt them to local conditions or to cancel any of the
above items, all without previous announcement and without giving reasons. KTM may stop manufacturing certain models without previous notice. KTM shall not be held liable for any deviations of availability and/or ability to deliver, illustrations, descriptions, printing and/or other errors. The illustrated models
partly contain extra equipment, which is not applied to standard models.
© 2007 by KTM-SPORTMOTORCYCLE AG, Mattighofen AUSTRIA; All rights reserved; Reprint, also in
extracts, with written allowance of KTM-SPORTMOTORCYCLE AG, Mattighofen only.

In accordance with the international quality management ISO 9001 standard, KTM uses
quality assurance processes that lead to the highest possible product quality.

IMPORTANT INFORMATION »

INTENDED PURPOSE
KTM mini-sports motorcycles are designed and constructed to resist the usual wear and tear of normal
use in competitions.
The motorcycles comply with the regulations and categories currently in effect with the leading international motorcycle associations.

ENGLISH
2

OWNER’S MANUAL
Please read this manual thoroughly before letting your youngster ride the motorcycle for the first time.
This manual contains important information and recommendations that will help you and your youngster
to operate and handle the motorcycle properly. In the interest of everybody involved, we urge you to pay
particular attention to instructions and information marked as follows:

– Ignoring these instructions can be dangerous to life and limb!

– Ignoring these instructions may damage parts of the motorcycle or impair the motorcycle's
traffic safety!

This manual contains important information on the operation and maintenance of your new KTM motorcycle. It went to press describing your model’s latest state of development. Nevertheless, the descriptions
may deviate slightly from the current design as our motorcycles are permanently improved.The Owner's
Manual is an integral part of the motorcycle and must be handed over to the new owner when the motorcycle is sold.

SERVICE
Observance of the service, maintenance and tuning instructions for the engine and chassis specified in
the Owner's Manual is a prerequisite for faultless operation and the avoidance of premature wear. An
improperly tuned chassis can lead to damage and breakage of the chassis components (see chapter on
checking the basic chassis setting).
The use of the motorcycle under extreme conditions, e.g. on extremely muddy and wet terrain, can lead
to higher than average wear on components such as the drive train or the brakes. In this case it may
become necessary to service or replace wear parts before the service limit specified in the maintenance
schedule has been reached.
We expressly point out that work marked with an asterisk (*) in the chapter "Maintenance work on the
chassis and engine" must be performed by a KTM workshop. If maintenance work should become necessary during a competition, it must be performed by a trained mechanic.
Please strictly observe the prescribed running-in periods and inspection and maintenance intervals.
Compliance with these instructions will significantly prolong the life of your motorcycle.

IMPORTANT INFORMATION »

WARRANTY
The service work specified in the "Lubrication and Maintenance Schedule" must be performed by a KTM
workshop and recorded in the service manual otherwise claims under the warranty shall become void.
No claims can be filed under the warranty for damage or consequential damage caused by manipulations
or conversions to the motorcycle.

SPARE PARTS, ACCESSORIES
For the safety of your child, only use spare parts and accessories approved by KTM. KTM shall not assume
any liability for other products or consequential damage resulting from the use of such products.
When special needs arise, please contact a KTM dealer, who will seek the assistance of the KTM importer
if necessary.

SAFETY
Parents should keep in mind that the safety of their youngsters always depends on the efforts made by
the parents to ensure that the motorcycle is kept in good working order and only used on safe terrains.
Nevertheless, driving the motorcycle, like driving any other vehicle, involves a potential risk. Therefore,
please make sure that all fundamental precautions are taken. Please also read the „INFORMATION ON
SAFE DRIVING FOR PARENTS“ on page 4.

TRANSPORT
When transporting your motorcycle, secure it with elastic straps or other mechaical devices in an upright
position. Be sure that the fuel tap is closed. If the motorcycle topples over, fuel can flow out of the carburetor or fuel tank.

ENVIRONMENT
Riding an off-highway motorcycle is a wonderful form of outdoor recreation and we certainly hope that
you and your youngsters will enjoy it to the full. However, this enjoyable outdoor activity can cause environmental problems or lead to conflicts with other people. Responsible use of the motorcycle will prevent
such problems and conflicts. You can contribute to securing the future of motorcycling by making sure
that you and your youngsters only use the motorcycle within the limits established by the applicable laws,
making environmental protection one of your top priorities and never violating other people’s rights.

In this spirit, we hope that you and your youngsters will always safely enjoy your motorcycle!

KTM-SPORTMOTORCYCLE AG
5230 MATTIGHOFEN, AUSTRIA

Attachments: 1 spare parts manual chassis & engine

ENGLISH

AUTOMOTIVE FLUIDS
The fuels and lubricants specified in the Owner's Manual or automotive fluids with equivalent specifications must be used in accordance with the maintenance schedule.

IMPORTANT INFORMATION FOR PARENTS ABOUT SAFE DRIVING »

ENGLISH

KTM mini motorcycles are off-road motorcycles designed for one person only. They are not allowed on
public roads.
The vehicle dimensions and components are designed for children from 4 to 10 years of age with a
maximum weight of. 35 kg (78 lbs) and a maximum height of 130 cm (51 in).

4
–

–

–
–
–
–
–
–

–

–
–
–

Have your youngster wear proper protective gear whenever he or she rides the motorcycle: helmet, eye
protection, chest, back, arm and leg protectors, gloves and boots. To set a good example, be sure to
wear protective gear yourself whenever riding a motorcycle!
Before your youngster takes his or her first ride, explain how each of the controls works and check if
your youngster has understood what you explained. We recommend to review the entire owner’s manual with your youngster item by item, paying particular attention to the specially marked warnings and
pointing out the danger of injury.
Instruct your youngster about riding and falling techniques, explain how the motorcycle will respond
to shifting of the rider’s weight, etc.
Before starting the motorcycle for the first time check whether the basic fork and shock absorber
settings are suitable for your child's weight (see chapter on checking the basic chassis setting)
Before using the motorcycle you should always check all components for proper operation (see mainenance schedule). Have your youngster perform these technical checks himself / herself as well.
Whenever you go for a ride with your youngster, keep in mind that the speed should be adjusted to
your youngster and not the other way around.
Your youngster must understand that all instructions he or she receives from you or any other supervising adult must be followed.
Your child must be physically ready to ride a motorcycle. This means that he or she must at least be
able to ride a bicycle. Being good at sports that require fast reactions is an additional advantage. Your
youngster should be strong enough to pick up the motorcycle after a fall.
Never demand too much of your youngster. Give him or her time to get used to the motorcycle and to
improve his / her riding skills. Do not even consider letting your youngster participate in a race before
his / her physical condition, riding skills and motivation have sufficiently developed.
Explain to your youngster that he / she should always adjust his / her riding speed to the local conditions as well as to his / her own riding skills and that excessive speed can cause falls and severe
injuries. Always keep in mind that youngsters tend to underestimate dangers or fail to recognize them
altogether. The riding speed must be reduced, in particular, on unknown terrain.
Never let your youngster ride the motorcycle without supervision. An adult should always be present.
The motorcycle is designed for one rider only. Your youngster is not allowed to transport a passenger.
When you go for a ride, somebody at home should always know where you are going and when you
will be back. This makes it easier to send you help, should problems occur.

TABLE OF CONTENTS »
Page

Page

IMPORTANT INFORMATION FOR PARENTS

Changing spring preloading of the shock absorber . . .20

ABOUT SAFE DRIVING . . . . . . . . . . . . . . . . . . . . . . . . .4

Check chain tension . . . . . . . . . . . . . . . . . . . . . . . .20
Correct chain tension . . . . . . . . . . . . . . . . . . . . . . .20

SERIAL NUMBER LOCATIONS . . . . . . . . . . . . . . . . . . . .6

Chain maintenance . . . . . . . . . . . . . . . . . . . . . . . . .20

Chassis number . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

General information about KTM disc brakes

Engine number

Setting the basic position and play of the hand brake lever . .21

. . . . . . . . . . . . . . . . . . . . . . . . . . . .6

. . . . . . .21

Checking the brake fluid level/ refilling . . . . . . . . . . .22
Checking front brake pads . . . . . . . . . . . . . . . . . . . .22

Throttle grip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

Replacing the front brake pads

Hand brake lever

Changing the basic position of the foot brake lever

. . . . . . . . . . . . . . . . . . . . . . . . . . .7

Short circuit button

. . . . . . . . . . . . . . . .22

. . . . . . . . . . . . . . . . . . . . . . . . .7

(50 SX Junior) . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

Filler cap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

Adjusting the control cable on the rear wheel (50 SX Junior) . .23

Fuel tap

Checking the rear brake linings for wear (50 SX Junior) . .23

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

Choke (Dell’Orto carburetor PHVA 14 DS) . . . . . . . . . .8

Drum brake maintenance (50 SX Junior)

Choke (Dell’Orto carburetor PHBG 19 BS)

. . . . . . . . .23

. . . . . . . . .8

Changing the basic position of the brake lever (50 SX) . .23

Kickstarter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

Checking the rear brake fluid level (50 SX) . . . . . . . .23

Foot brake lever . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

Refilling the rear brake fluid reservoir (50 SX) . . . . . .24

Side stand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

Checking rear brake pads (50 SX)

Plugin - Stand (50 SX) . . . . . . . . . . . . . . . . . . . . . . .9

Replacing the rear brake pads (50 SX) . . . . . . . . . . . .24

Rebound damping function of the shock absorber . . . .9

Removing and mounting the front wheel . . . . . . . . . .25

General Tips and Warnings for starting the motorcycle . .10

Removing and mounting the rear wheel

Instructions for the first ride . . . . . . . . . . . . . . . . . .10

Tires, air pressure . . . . . . . . . . . . . . . . . . . . . . . . . .26

Running in

Checking spoke tension

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

. . . . . . . . . . . . . .24

. . . . . . . . . .25

. . . . . . . . . . . . . . . . . . . . .26

Driving instructions . . . . . . . . . . . . . . . . . . . . . . . . .11

Cooling system . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

What you should check before each start

Checking coolant level

Starting when the engine is cold
Starting when the engine is warm

. . . . . . . . . . . . . . .12
. . . . . . . . . . . . . .12

What to do when the engine is “flooded”
Starting off
Driving

. . . . . . . . .11

Cleaning the air filter
Exhaust system

. . . . . . . . . . . . . . . . . . . . . .27
. . . . . . . . . . . . . . . . . . . . . . .27

. . . . . . . . . . . . . . . . . . . . . . . . . . .27

. . . . . . . . .12

Changing the seat height . . . . . . . . . . . . . . . . . . . . .28

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12

Adjusting the throttle cable . . . . . . . . . . . . . . . . . . .28

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12

Adjusting the idle speed (Dell’Orto PHVA 14 DS)

. . .28

Refueling, fuel . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

Adjusting the idle speed (Dell’Orto PHBG 19 BS) . . .28

Braking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

Checking the gear oil level

Stopping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

Changing gear oil . . . . . . . . . . . . . . . . . . . . . . . . . .29

. . . . . . . . . . . . . . . . . . .29

Adjusting the centrifugal clutch . . . . . . . . . . . . . . . .30
PERIODIC MAINTENANCE SCHEDULE . . . . . . . . . . . . .14
TROUBLE SHOOTING . . . . . . . . . . . . . . . . . . . . . . . . .32
MAINTENANCE WORK ON CHASSIS AND ENGINE . . . .16
Removing the seat . . . . . . . . . . . . . . . . . . . . . . . . .16

CLEANING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34

Checking and adjusting the steering head bearing
(50 SX Junior) . . . . . . . . . . . . . . . . . . . . . . . . . . . .16

STORAGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34

Checking and adjusting the steering head bearing
(50 SX) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
How to change the handlebar position

TECHNICAL DATA – ENGINE . . . . . . . . . . . . . . . . . . . .35

. . . . . . . . . . .17

Basic suspension setup for the weight of the driver . .18

TECHNICAL SPECIFICATIONS - CHASSIS . . . . . . . . . . .36

To determine the sag of the shock absorber . . . . . . . .18
To determine the sag of the telescopic fork

. . . . . . .18

Telescopic fork maintenance . . . . . . . . . . . . . . . . . .19
Changing the telescopic fork oil . . . . . . . . . . . . . . . .19
Cleaning the dust scrabbers of the telescopic fork . . .20

HEAD WORD INDEX . . . . . . . . . . . . . . . . . . . . . . . . . .37

ENGLISH

OPERATION INSTRUMENTS . . . . . . . . . . . . . . . . . . . . .7

SERIAL NUMBER LOCATIONS »
Chassis number
The chassis number is located on the type plate on the steering head. Enter
this number in the field on page no 1.

Engine number

ENGLISH
6

The engine number is stamped into the right half of the engine case next to
the kickstarter. Enter this number in the relevant field on page 1.

OPERATION INSTRUMENTS »
Throttle grip
The throttle grip is located on the right side of the handlebars. It is used to
reduce the engine speed and, thus, the driving speed.

The hand brake lever is located on the right side of the handlebars and
actuates the front wheel brake. The basic position can be adjusted to fit your
child's hand.

ENGLISH

Hand brake lever

Short circuit button

The short circuit button [1] turns off the engine. When pressing this button,
the ignition circuit is short-circuited.

Filler cap
To open it: turn filler cap counter-clockwise.
To close it: put filler cap back on and tighten it by turning it clockwise.

Install tank breather hose [2] without kinks.

Fuel tap
The fuel tap [3] is located at the front of the motorcycle on the left side of
the tank.
Opening the fuel tap: Turn the knob all the way to the left.
Closing the fuel tap: Turn the knob all the way to the right.

OPERATION INSTRUMENTS »
Choke Dell’Orto carburetor PHVA 14 DS (50SX Junior)
Choke lever [1] is mounted to the right side of the carburetor. If you move
the choke lever up to the stop, a hole is opened in the carburetor through
which the engine can draw in additional fuel. This results in a "rich" fuel-air
mixture required for a cold start.
Moving the choke lever back closes the hole in the carburetor again.

Choke Dell’Orto carburetor PHBG 19 BS (50 SX)

ENGLISH

Choke control knob [2] is mounted to the left side of the carburetor. If you
pull the choke control knob up to the stop and turn it 90º, a hole is opened
in the carburetor through which the engine can draw additional fuel. This results
in a "rich" fuel-air mixture required for a cold start.
Turning back the choke control knob returns the knob to the starting position
and closes the hole in the carburetor again.

Kickstarter
The kickstarter is mounted on the right side of the engine. Its upper part can
be swivelled.

Foot brake lever
The foot brake lever is located in front of the right footrest. The basic position can be adjusted to the seating position (see maintenance work).

Side stand (50 SX Junior)
Use your foot to swing the side stand forwards to the stop. Make sure it rests
securely on solid ground.

OPERATION INSTRUMENTS »
Plugin - Stand (50 SX)
A socket is provided on the left side of the frame for the plug-in stand [1]
included in the scope of supply.

By using the adjusting screw [2], the degree of damping of the rebound can
be adjusted. Turn the knob clockwise to increase damping, turn it counterclockwise to reduce damping during rebounding.
STANDARD ADJUSTMENT:
– turn the adjusting screw clockwise to the stop.
– then turn the adjusting screw counterclockwise, counting the number of
clicks that corresponds to the respective type of shock absorber.

ENGLISH

Rebound damping function of the shock absorber

50 SX Junior: . . . . . . . . . .12
50 SX: . . . . . . . . . . . . . . .10

9
– Never turn the setting wheel more than two clicks between two test rides.
– Do not try to disassemble the shock absorber or to perform maintenance
work yourself. Danger of injury!

GENERAL TIPS AND WARNINGS FOR STARTING THE MOTORCYCLE »

Instructions for the first ride

ENGLISH
10

– Make sure the work for the "pre-delivery inspection" was performed by your authorized KTM workshop. The DELIVERY
CERTIFICATE and SERVICE MANUAL will be handed over
when you pick up your vehicle.
– Before your youngster takes his or her first ride, explain how
each of the controls works and check if your youngster has understood what you explained. We recommend to review the entire
owner’s manual with your youngster item by item, paying particular attention to the specially marked warnings and pointing out the danger of injury.
– Adjust the basic position of the hand brake lever to fit the size
of your child's hand. You child should of course wear gloves.
Adjust the foot brake lever to your child's seating
position.
– To prevent injury, teach your youngster the basic riding skills
on soft ground, e.g. on a meadow or in the garden. Be sure
that there is room enough to maneuver, and that no other riders are close.
– To ensure that your youngster gets the feel of the brakes, have
your youngster operate the brakes while you push the motorcycle. Do not start the engine before your youngster has learned
to apply both brakes with appropriate pressure.
– Now your youngster must get the feel of the throttle. Start the
engine, hold the motorcycle and have your youngster slowly
open the throttle. Then, your youngster can take his/her first
ride. Initially, your youngster should ride back and forth between
two persons who help the young rider to stop the motorcycle.
However, you should also teach your youngster how to stop the
motorcycle himself/herself.
– To improve his/her riding skills, your youngster should practise
to ride the motorcycle standing on the footpegs or riding at the
slowest possible speed. Additionally, you can arrange a series
of obstacles and have your youngster drive around them, etc.
– Tell your youngster to look 3-10 m ahead, depending on the
speed, to recognize and avoid obstacles. When riding through
curves, the rider should also look far ahead into the curve.
– Pay attention to running-in procedure.

Running in
– Even very precisely machined sections of engine components
have rougher surfaces than components which have been sliding across one another for quite some time. Therefore, every
engine needs to be broken in. Do not load the engine to the
power limit during the first half hour for this reason.
– Apply low but changing loads for running-in.
– NO FULL-LOAD OPERATION DURING THE FIRST HALF HOUR!
– Have your youngster wear proper protective gear whenever he
or she rides the motorcycle: helmet, eye protection, chest, back,
arm and leg protectors, gloves and boots. To set a good example, be sure to wear protective gear yourself whenever riding a
motorcycle!
– The motorcycle has a centrifugal clutch. The motorcycle begins
to move as soon as the throttle is opened.
– Always apply the front brake when starting the engine and release
the brake slowly when the engine is running. An activated
choke increases the idle speed of the engine, the centrifugal
clutch thus beginning to engage. Therefore, the motorcycle can
begin to move when the brake levers are released.
– When the engine speed drops to the level at which the centrifugal clutch disengages, braking with the engine is no longer
possible and the motorcycle can only be slowed down using
the brakes.
– Your child should never drive faster than its skills and the terrain permit.
– Never let your child drive its motorcycle unchaperoned.
– Replace the helmet visor or goggle glasses early enough. When
light shines directly on a scratched visor or goggles, you will
be practically blind.
– Only use accessory parts recommended by KTM.
– Never leave your motorcycle without supervision as long as the
engine is running.
– KTM mini models are designed for one person only. Passengers
are not allowed.
– These models do not comply with the regulations and safety
standards established by the law. Therefore, they are not permitted on public roads.
– Always keep in mind that other people feel molested by excessive noise.

DRIVING INSTRUCTIONS »

When you start off, the motorcycle must be in a perfect technical condition.
For safety reasons, you should make it a habit to perform an overall check of
your motorcycle before each start.
The following checks should be performed:
1 CHECK TRANSMISSION OIL LEVEL
A lack of gear oil leads to premature wear and finally results in destruction of the gear wheels.
2 FUEL
Check that there is sufficient fuel in the tank; when closing the filler cap,
check that the tank venting hose is free of kinks.
3 COOLING FLUID
Check the level of cooling fluid when the engine is cold.
4 CHAIN
A loose chain was fall off the chain wheels; an extremely worn chain may
tear, and insufficient lubrication may result in unnecessary wear of the
chain and chain wheels.
5 TIRES
Check for damaged tires. Tires showing cuts or dents must be replaced.
Also check the air pressure. Insufficient tread and incorrect air pressure
deteriorate the driving performance.
6 BRAKES
Check for proper functioning, check brake fluid level in the tank. The
tank is designed such that it does not need to be refilled, even if the
brake shoes are worn. If the brake fluid falls below the minimum level,
the brake system is either leaking or the brake shoes are completely worn
out. Have the brake system checked at a KTM workshop to avoid brake
failure. Also have the condition of the brake hose and the brake lining
thickness checked.
Check the play of the hand brake lever and foot brake lever.
7 THROTTLE CABLE
Check the throttle cable for proper adjustment and smooth operation.

ENGLISH

What you should check before each start

DRIVING INSTRUCTIONS »

Starting when the engine is cold

ENGLISH

1
2
3
4
5

1
12

Open fuel tap [1].
Operate the choke [2].
Kick the side up all the way or remove the plug-in stand.
Apply the front brake.
Operate the kickstarter, depressing it all the way, without opening the throttle.

– When starting the engine, put on motorcycle boots in order to avoid
injuries. You may slip off the kickstarter, or the engine may kick back if
you do not kick hard enough.
– Do not start the engine and allow it to idle in a closed area. Exhaust fumes
are poisonous and can cause loss of consciousness and death. Always provide adequate ventilation while the engine is running.
Don’t ride your motorcycle with full load and high revs when engine is cold.
Because the piston is warming up faster than the water cooled cylinder, it can
cause engine damage.

NOTE:
The highly inflammable components in modern fuels volatilize if left standing for longer periods of time. If the motorcycle has not been used for over
1 week, the fuel should be drained from the float chamber. The engine will
start up immediately if the float chamber is filled with fresh, ignitable fuel

Starting when the engine is warm
1
2
3
4

Open fuel tap [1].
Kick the side up all the way or remove the plug-in stand.
Apply the front brake.
Operate the kickstarter, depressing it all the way, without opening the throttle.

What to do when the engine is “flooded”
1 Close fuel tap [1].
2 Applying the front brake.
3 Start engine with full throttle. If necessary, unscrew spark plug and
dry it.
4 Once the engine is running, open fuel tap again.

Starting off
Slowly release the brake lever while simultaneously opening the throttle.
Always make sure the side stand is kicked all the way up or the plug-in stand
removed before you let your child drive off. The motorcycle could run out of
control if the stand touches the ground.

DRIVING INSTRUCTIONS »

The engine speed, and thus the driving speed, are regulated by
the throttle grip.
The choke must always be deactivated as soon as the engine has
warmed up.
– After falling with the motorcycle, check all its functions thoroughly before using it again.
– A bent handlebar must always be replaced. Never try to
straighten the handlebar because this will cause it to lose its
stability.
– Driving a cold engine at high speed will reduce the life of the
engine. We recommend to warm the engine up at a medium
engine speed for several minutes before switching to full load.
– Never tilt the motorcycle over the side stand to warm up the
engine. The side stand could fold away and the motorcycle run
out of control.
– In the event that, while your child is riding on the motorcycle,
you notice any unusual operation-related noise, your child
should stop immediately, turn the engine off, and contact an
authorized KTM dealer.

Braking
Close the throttle and squeeze both brake levers simultaneously.
On sandy, wet or slippery terrain the rear wheel brake should be
preferred. The brakes should always be operated carefully as
locking wheels can cause skidding or falls.
– Brake drum and linings heat up during brake operation, thus
reducing the effect of the brakes.
– Wet brakes have reduced brake performance, therefore be sure
to brake them dry after cleaning.
– If the resistance of the hand brake lever feels unresponsive,
something is wrong with the brake system. Have the brake system checked at a KTM workshop before you let your child drive
the motorcycle.

Stopping
Reduce the speed. Immediately before the motorcycle comes to
a stop, put the left foot down. To turn off the engine, press the
short circuit button until the engine stops. Close the fuel tap.
Motorcycles produce great heat during operation. Therefore, keep
in mind that the engine, the exhaust system and the brakes can
heat up considerably. Make sure that these parts are not touched
and always take care, when parking the motorcycle, that other persons will not burn themselves.

– Close the fuel tap when leaving the motorcycle. Otherwise the
carburetor may get flooded and fuel will enter the engine.
– The side stand or plug-in stand is designed to hold the weight
of the motorcycle only. By sitting on the motorcycle, your child
will put additional weight on the side stand, possibly causing
the side stand or frame to be damaged or the motorcycle to
fall down.

Refueling, fuel
Oil (high-grade two-stroke engine oil) must be mixed with the fuel
(ROZ 95) at a mixing ratio of 1:60.
Fuel and engine oil should only be mixed immediately before
use.KTM recommends Motorex 2T Cross Power.
Gasoline is highly flammable and poisonous. Extreme caution
should be used when handling gasoline. Never refuel the motorcycle near open flames or burning cigarettes. Always switch off
the engine before refueling. Be careful not to spill gasoline on the
engine or exhaust pipe while the engine is hot. Wipe up spills
promptly. If gasoline is swallowed or splashed in the eyes, seek a
doctor’s advice immediately.
– Only use premium-grade gasoline ROZ 95 mixed with highgrade two-stroke engine oil. Other types of gasoline can cause
engine failure.
– Only use known brands of high-grade 2-stroke engine oil
(Motorex 2T Cross Power).
– Not enough oil or low-grade oil can cause erosion of the piston. when Using too much oil, the engine may start smoking
and foul the spark plug.
– Fuel expands when its temperature rises. Therefore do not fill
the tank to the top. (see fig.)

40 mm

ENGLISH

Driving

Service every
5 hours

Service every
20 hours

50 SX JUNIOR
50 SX

Check engine for leaks

Change transmission oil

ENGINE

A CLEAN MOTORCYCLE CAN BE CHECKED MORE QUICKLY WHICH SAVES MONEY!

CHASSIS

Check intake flange for cracks

Check idle setting when engine is warm

Check cooling system for leaks, check quantity of antifreeze

Check exhaust system for leaks and suspension

Check actuating cables for damage, smooth operation, and kinkless arrangement, adjust and lubricate

Clean air filter and air filter box

Check/function adjust smooth operation, free travel of handbrake/footbrake levers

Check screws of brake system for a tight fit

Check suspension strut and fork for leaks and a proper function

Check swinging-fork pivot

Check/adjust steering-head bearing

Check all chassis screws for a tight fit (fork plates, axle nuts, swinging-fork pivot, suspension strut)

Check the brake line and the brake control cable for damage

Check spoke tension and rim joint
WHEELS

Check carburetor for a tight fit at intake flange

Check brake fluid level, lining thickness, brake discs
BRAKES

ENGLISH

ADD-ON-PARTS CARBURETOR

Check spark plug, change it if necessary, set electrode gap
Check the clutch engagement speed

before every
race

PERIODIC MAINTENANCE SCHEDULE »

Check tire condition and inflation pressure
Check chain, chain joint, chain wheels, chain wheel guides for wear, a tight fit, and tension

Lubricate chain

Check wheel bearings for play

PERIODIC MAINTENANCE SCHEDULE »

Check the clutch shoes for wear

Check the clutch drum for wear

Check the water pump shaft and bearings for wear

Check the water pump wheel for wear

Check the cylinder and piston for wear

Check the eccentricity of the crankshaft journal

Check the radial clearance of the conrod bearings

Check the radial clearance of the piston pin main bearing

Check the crankshaft main bearing for wear

Replace the crankshaft bearings and conrod bearings

Check the entire transmission including bearings for wear

ENGLISH

every
40 hours

Check the reed-type intake valve for wear

ADDITIONAL SERVICE WORK TO BE PERFORMED UNDER A SEPARATE ORDER

once a year

every
20 hours

50 SX JUNIOR
50 SX

Drain and clean the carburetor's float chamber

Perform complete fork maintenance

Perform complete shock absorber maintenance

Clean and lubricate the swinging-arm bearing

Clean and lubricate the steering-head bearing and sealing elements

Change brake fluid

NOTE:

If the inspection establishes that permissible tolerances are exceeded, the respective components must be replaced.

The kilometer reading for inspection intervals should not exceed 5 hours.
Maintenance work performed by your authorized KTM workshop is not a substitute for care and maintenance by the driver!

Check transmission oil level

Check cooling liquid level

Check brake fluid level

Check brake pads for wear

Check brake performance

z
z

Lubricate and adjust actuating cables and nipples

Remove and clean dust sleeves of telescopic fork at regular intervals
z

Clean and lubricate chain, check tension and readjust it if necessary
Check tire inflation pressure and wear

Check fuel line for leaks

z
z

Drain and clean float chamber
Treat exposed metal components (except for the brake and exhaust systems)

z
z

Clean air filter and filter box

Verify smooth operation of all controls

once a year

VITAL CHECKS AND CARE PROCEDURES TO BE CONDUCTED BY THE OWNER OR THE MECHANIC

for cross country
use

50 SX JUNIOR
50 SX

after every
cleaning

A service hour counter (item no.: SXS05450600) is available from your KTM dealer for strict observance of the service
intervals.

before each start

NOTE:

z
z

with wax-based anti-corrosion agents
Check all screws, nuts, and hose clamps for their tight fit at regular intervals

MAINTENANCE WORK ON CHASSIS AND ENGINE »
Maintenance work and adjustments marked with an asterisk (*) must be performed by an expert. To protect your youngster, always have
such work performed by a specialized KTM dealer where your motorcycle will be optimally serviced by appropriately qualified, skilled
staff.

ENGLISH

– When cleaning the motorcycle, do not use a high pressure cleaning unit if possible, otherwise water will penetrate the bearings,
carburetor, electric connectors, drum brakes, etc.
– Before cleaning with water, plug the exhaust pipe to prevent water ingress.
– When transporting your motorcycle, secure it with elastic straps or other mechanical devices in an upright position. Be sure that
the fuel tap is closed. If the motorcycle topples over, fuel can flow out of the carburetor or fuel tank.
– Do not use toothed washers or spring rings with the engine fastening screws, as these work into the frame parts and keep working
loose. Instead, use self-locking nuts.
– Let your motorcycle cool down before beginning any maintenance work in order to avoid getting burned.
– Dispose of oils, fatty matters, filters, fuels, washing detergents, etc. properly.
– Under no circumstances may used oil be disposed of in the sewage system or in the open countryside. 1 liter of used oil contaminates 1,000,000 liters of water.

Removing the seat

The quick-release mechanism [1] allows removal of the seat without tools.
Turn the quick-release device approximately 180° counterclockwise, lift the
rear portion of the seat and pull the seat off backwards.
When mounting the seat ensure that the hook engages at the tank.

Checking and adjusting the steering head bearing (50 SX Junior) *

3
2

4
3
2
4

The steering head bearing should be checked regularly for play. For this
purpose, jack up the motorcycle by the frame so that the front wheel is in the
air. Now try to move the fork forward and backward. There should be no clearance. For readjustment, release the two clamp screws [2] of the top triple
clamp and the counternut [3]. Turn the adjusting nut [4] until almost no play
is left. Do not tighten the adjusting nut! Tightening the adjusting nut can
damage the bearings! Keep in mind that tightening the counternut [3] reduces
the play of the bearing. Slightly tap the top triple clamp with a rubber hammer to prevent jamming. Then tighten the 2 clamp screws with 25 Nm.
If the steering head bearing is not adjusted to be free of clearance, the motorcycle will exhibit unsteady driving characteristics and can get out of control.
– The handlebar must move easily. Otherwise the bearings will be damaged.
– If you drive with play in the steering head bearing for longer periods, the
bearings and subsequently the bearing seats in the frame will be destroyed.
At least once a year, the steering head bearings should be smeared with waterproof grease (Motorex Long Term 2000).

MAINTENANCE WORK ON CHASSIS AND ENGINE »
Checking and adjusting the steering head bearing (50 SX) *

The steering head bearing should be checked regularly for play. To check,
support the motorcycle frame and lift the front wheel off the ground. Now try
to move the fork back and forth – you should not feel any play. To adjust,
loosen both clamping screws [1] on the upper triple clamp and loosen the
steering head screw [2] by a few turns. Lift the triple clamp slightly and turn
the adjusting nut [3] until hardly any play is left. Never tighten the adjusting
nut since you might damage the bearing. Tighten the steering head screw to
a torque of 10 Nm and the 2 clamping screws to 25 Nm.
If the steering head bearing is not adjusted to be free of clearance, the motorcycle will exhibit unsteady driving characteristics and can get out of control.

ENGLISH

– The handlebar must move easily. Otherwise the bearings will be damaged.
– If you drive with play in the steering head bearing for longer periods, the
bearings and subsequently the bearing seats in the frame will be destroyed.

3
17

At least once a year, the steering head bearings should be smeared with waterproof grease (Motorex Long Term 2000).

1
3

How to change the handlebar position
The handlebar position can be readjusted by 22 mm (0.9 in). The upper triple
clamp [4] includes 2 bores arranged at a distance of 15 mm (0.6 in) from
one another. The bores at the handlebar support [5] are offset from the
center by 3.5 mm (0.13 in). Accordingly, you can mount the handlebar in 4
different positions.

6
7
mm
15

3,5 mm

For this purpose, remove screws [6] of the handlebar clamps and screws [7]
of the handlebar support. Position handlebar support, and tighten screws [7]
to 40 Nm. Mount handlebar and handlebar clamps, and tighten screws [6]
to 20 Nm. The gap between the handlebar support and handlebar clamps
should be the same size in the front and in the rear.
The screws [7] must be secured with Loctite 243.

MAINTENANCE WORK ON CHASSIS AND ENGINE »
Basic suspension setup for the weight of the driver

To achieve maximum handling performance and to prevent the telescopic fork
and shock absorber from being damaged, the basic setup of the suspension
components must be suitable for your child's weight. At delivery, KTM's mini
motorcycles are set to accommodate a driver weighing 25 - 30 kg (wearing
full protective clothing). If your child's weight exceeds or falls short of this
range, you will need to adjust the spring preload for the telescopic fork and
shock absorber accordingly.
To adjust, check the sag of the shock absorber and telescopic fork. The motorcycle should be filled up and your child should be wearing full protective
clothing.

To determine the sag of the shock absorber

ENGLISH

B
B

– Jack up the motorcycle until the rear wheel no longer touches the ground.
– Measure the vertical distance between the rear wheel axle and a fixed point
(e.g. a mark on the side cover) and write it down as dimension A.
– Place the motorcycle on the ground again.
– Have your child sit on the motorcycle in a normal seating position
(feet on the footrests) wearing full protective clothing and bounce up and
down a few times to allow the rear wheel suspension to become level.
– Holding your child and the bike, have another person measure the
distance between the same two points with the load on the motorcycle to
establish dimension B.
– The sag is the difference between dimensions A and B.
EXAMPLE:
Motorcycle jacked up (dimension A) . . . . . . . . . . . . . . . . . . . . . .400 mm
Motorcycle on ground with driver seated (dimension B) . . . . . . .– 355 mm
Sag . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45 mm

50 SX Junior shock absorber sag . . . . . . . . . . . . . . . . . 45 mm (± 5 mm)
50 SX shock absorber sag . . . . . . . . . . . . . . . . . . . . . . 50 mm (± 5 mm)

If the sag is lower, the spring preload of the shock absorber must be reduced,
if the sag is higher, the spring preload must be increased (see Changing spring
preloading of the shock absorber). A harder spring is also available for the
50 SX (see spare parts catalog).

To determine the sag of the telescopic fork
– Jack up the motorcycle until the rear wheel no longer touches the ground.
– Measure the distance between the upper edge of the slider tube and the
triple clamp and write it down as dimension C.
– Have your child sit on the motorcycle in a normal seating position
(feet on the footrests) wearing full protective clothing, and bounce up and
down a few times to allow the telescopic fork to become level.
– Holding your child and the bike, have another person measure the
distance between the same two points with the load on the motorcycle to
establish dimension D.
– The sag is the difference between dimensions C and D.
EXAMPLE:
Motorcycle jacked up (dimension C) . . . . . . . . . . . . . . . . . . . . . .200 mm
Motorcycle on ground with driver seated (dimension D) . . . . . . .– 160 mm
Sag . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40 mm

1
D
D

50 SX Junior telescopic fork sag . . . . . . . . . . . . . . . . . 30 mm (± 5 mm)
50 SX telescopic fork sag . . . . . . . . . . . . . . . . . . . . . . 45 mm (± 5 mm)
If the sag is lower, the spring preload of the telescopic fork must be reduced,
if the sag is higher, the spring preload must be increased.
The preload on the fork spring is determined by the length of preload spacer
[1]. If an adjustment is necessary, demount the fork legs, remove the plugs
and shorten the pretensioning sleeves or replace with longer ones
(see maintenance of telescopic fork). Harder fork springs are also available
for both models (see spare parts catalog).

MAINTENANCE WORK ON CHASSIS AND ENGINE »
Telescopic fork maintenance *
The telescopic fork must be serviced at least once a year.
To service the fork, proceed as follows:
Prop up the motorcycle under the frame to take the load off the front wheel.
Disassemble the front wheel, remove screw [1] from the brake caliper and
unscrew holding clamp. Measure the projection of the fork legs at the upper
fork stabilizer and make a note of the measurement.
Loosen the clamping screws [2] on the fork stabilizers and pull the fork legs
down out of the fork stabilizers.

1
2

Clamp the fork leg into a vise (use protective jaws) and remove the
plugs [3]. Take the preload spacer and the spring out of the fork tube.
Remove screws [4] at the underside of the slider tubes and pull the fork tubes
out of the slider tubes.
Remove the dust scrabbers [5].

ENGLISH

– Do not operate the hand brake when the front wheel has been dismounted.
– Make sure the brake disc is always on top when you lay down the wheel,
otherwise the brake disc can be damaged.

Thoroughly clean all parts and check for wear.
Generously lubricate seals and springs and reassemble the telescopic fork.
Tighten the screws on the bottom of the sliding tubes to 30 Nm.
Fill in fork oil and assemble the fork (see below). Degrease the screws on the
brake caliper and apply Loctite 243. Mount the brake caliper and tighten to
20 Nm. Mount brake line and holding clamp.
Insert fork legs in the fork stabilizers (projection as previously noted) and tighten
clamping screws to 25 Nm (top) and 10 Nm (bottom).
Mount front wheel (see chapter: mounting the front wheel).
The screws [1] must be secured with Loctite 243.

Changing the telescopic fork oil *
Remove front wheel and fork legs (see above).
Remove plugs, preload spacers and springs.
Drain the fork oil into an appropriate container.
Clean the dust scrabbers.
– It is very important to keep the brake disk free from oil and fatty matters.
Otherwise, the braking effect would be strongly reduced.
– After working on the brake system, always operate the hand brake lever
to apply the brake shoes to the brake disk and have a point of pressure.

Pour 170 cm3 SAE 7.5 fork oil into each fork tube.
Slide the fork tube all the way into the slider tube.
Adjust the air-chamber length [A] to 110 mm (4.5 in) by extracting or adding
fork oil.
Insert springs and pretensioning sleeves into the fork tube.
Check O-rings, grease and mount plugs.
Mount the fork legs, front wheel and brake caliper (see above).

MAINTENANCE WORK ON CHASSIS AND ENGINE »
Cleaning the dust scrabbers of the telescopic fork
The dust-protection bellows [1] are to remove dust and coarse dirt particles
from the fork tube. However, after some time, dirt may also get in behind the
dust-protection bellows. If this dirt is not removed, the oil sealing rings located
behind it may start to leak.
For this purpose, use a screwdriver to lift the dust scrabbers out of the
slider tubes, clean them thoroughly with compressed air, spray the fork tubes
and dust scrabbers with Universal oil spray (Motorex Joker 440) or engine oil.
Then, push the dust-protection bellows into the outer tubes by hand.

No oil may reach the front tire or the brake disks since this would considerably reduce the tire's road grip and the braking effect of the front brake.

Changing spring preloading of the shock absorber
2

ENGLISH

This is easily done.
NOTE: Before changing the spring preload note down the basic setting, e.g.
how many threads are visible above the adjusting ring.

Remove the right side cover.
Loosen the locking ring [2] with the hook spanner. Change the spring preload
with the adjusting ring [3] and re-tighten the locking ring [2].
BASIC SETTING – SPRING PRELOAD:
50 SX Junior: . . . . . . . . . .5 mm (0.2 in)
50 SX: . . . . . . . . . . . . . . .3 mm (0.12 in)

Check chain tension

10 mm
A

Put the motorcycle on the sidestand.
Chain tension has to be checked close to the lower rear shock mounting [A].
When pushing the chain upwards, the distance to the swingarm has to be
10 mm (0.4 in).
If necessary, correct chain tension.
– If chain tension is too great, parts within the secondary transmission (chain,
chain wheels, gear box and rear wheel bearings) will be subjected to unnecessary stress, resulting in premature wear and even chain breakage.
– Too much slack in the chain, on the other hand, can result in the chain
jumping off the chain wheels. If this happens, the chain could also block
the rear wheel or damage the engine. In either case the operator is likely
to lose control of the motorcycle.
– Be careful not to get your finger caught between the chain and the rear
sprocket or other components.

Correct chain tension

Release the hexagon nut of the wheel spindle [4] and turn the left and the
right hexagon nut [5] equally far.
Before tightening the hexagon nut of the wheel spindle to 40 Nm, ensure that
the supporting plates [6] are resting against the swing arm. Additionally,
check that the rear wheel is aligned with the front wheel.

5
Chain maintenance
For long chain life, good maintenance is very important. Chains without
O-rings should be cleaned in fireproof solvent regularly and afterwards
treated with hot grease or chain spray (Motorex Chainlube Racing).
Keep the rear wheel free of grease! Grease on the rear wheel will significantly
reduce the grip of the rear tire and the motorcycle could easily get out of
control.
When mounting the chain masterlink clip, the closed side of the masterlink
clip must point in running direction.
Also check sprockets and chain guides for wear, and replace if necessary.

MAINTENANCE WORK ON CHASSIS AND ENGINE »
General information about KTM disc brakes
BRAKE FLUID RESERVOIRS:
The brake fluid reservoirs for the front brake is designed such that it does not
need to be refilled, even if the brake shoes are worn. If the brake fluid level
drops below the minimum level either the brake system has a leak or the brake
pads are completely worn.
In this case, consult an authorized KTM dealer immediately.

Have the brake fluid changed at least once annually. If you wash your motorcycle often, the brake fluid should be changed even more frequently. Brake
fluid tends to absorb water. Therefore, vapor pockets may form in "old" brake
fluids even at low temperatures, causing the brake system to fail.
BRAKE DISC:
Due to wear, the thickness of the brake disc in the area of the contact
face [1] of the brake pads decreases. The brake disk must be at least 2.50
mm thick at the thinnest point [A]. Check the thickness of the brake disk at
several points.

– A brake disk worn down to less than 2.50 mm is a safety risk. Have the
brake disk replaced as soon as it reaches the service limit.
– Have any repairs on the brake system be performed by a KTM dealer.
BRAKE CALIPERS:
Secure the screws on the brake caliper with Loctite 243 and tighten to a torque
of 20 Nm.

Setting the basic position and play of the hand brake lever *
You can adjust the basic position of the hand brake lever to fit your child's
hand by turning stop screw [2]. Afterwards, be sure to adjust the play of the
hand brake lever to 2 mm (0.08 in)with the adjusting screw [3]. To adjust,
remove covering cap [4]. Replace the covering cap after making the adjustment.

min. 2 mm
4

At the hand brake lever, free travel must at least be 2 mm (0.08 in). Only
then may the piston in the hand brake cylinder be moved (to be recognized
by the greater resistance of the hand brake lever). If this free travel is not provided, pressure will build up in the braking system, and the front-wheel brake
may fail due to overheating.

ENGLISH

BRAKE FLUID:
We recommend that you use Motorex DOT 5.1 brake fluid when you refill or
change the brake fluid. DOT 5. 1 brake fluid has a wet boiling point of 180°C
/ 356°F (25°C / 45°F higher than DOT 4) and is safer for high performance
applications. Brake fluid DOT 5.1 is a polyethylene glycol based fluid, ambercolored and can be mixed with DOT 4 brake fluid. Do not, in any event, use
DOT 5 brake fluid. It is based on silicone oil and is dyed purple. KTM motorcycle gaskets and brake hoses are not designed for DOT 5 brake fluid.

MAINTENANCE WORK ON CHASSIS AND ENGINE »
Checking the brake fluid level / refilling *

ENGLISH

5 mm

The brake fluid reservoir is combined with the hand brake cylinder on the
handlebar. To check the brake fluid level, press the brake pistons back into
the basic position. Move the hand brake cylinder in a horizontal position, remove
the screws [1] and the cover [2] with the diaphragm [3]. The brake fluid level
should be 5 mm below the upper edge of the reservoir (see drawing),
otherwise add DOT 5.1 brake fluid (e.g. Motorex Brake Fluid DOT 5.1) up to
5 mm below the upper edge of the reservoir.
Mount the diaphragm, the cover and the screws and actuate the hand brake
lever until you feel the point of pressure again. Wipe off any overflowing or
spilled brake fluid with water.
– Actuate the hand brake lever until you feel the point of pressure again.
– Never use DOT 5 brake fluid! It is based on silicone oil and of a purple
color. Seals and brake hoses must be especially adapted to it.
– Store brake fluid out of reach of children.
– Brake fluid can cause skin irritation. Avoid contact with skin and eyes. If
you get brake fluid in your eyes, rinse with plenty of water and consult a
doctor.
– Don’t let brake fluid get in contact with paint, it is an effective
paint remover.
– Use only clean brake fluid taken from a tightly sealed container.

Checking front brake pads

min.
1 mm

Inspect the brake pads from in front of the vehicle. The linings must be at
least 1 mm (0.04 in) thick.
At their most worn point brake pad linings should not be thinner than 1 mm
(0.04 in), otherwise they could lead to brake failure. For your own safety don’t
put off having your brake pads changed.
If the brake pads are replaced too late so that the lining is partly or entirely
worn, the steel components of the brake pad will rub against the brake disc,
thereby imparing the braking effect and destroying the brake disc.

Replacing the front brake pads *
Remove the front wheel (see front wheel chapter).
Press brake shoes apart with a suitable screwdriver to put the brake pistons
in their basic position.
Remove the lock washer [4] from the screw as well as fixing screw [5] and
take the brake shoes out of the brake caliper. Clean brake caliper thoroughly
with compressed air.

Mount the left brake shoe and fix with screw. Mount the right brake shoe and
tighten the screw to 4 Nm. Mount the lock washer. Align brake shoes, mount
front wheel (see chapter: Mounting the front wheel).

– It is very important to keep the brake disk free from oil and fatty matters.
Otherwise, the braking effect would be strongly reduced.
– After assembly, check if circlips have been fitted correctly.
– Do not unscrew any other screws on the brake caliper or you will have to
bleed the brake system.
– After working on the brake system always operate the hand brake lever to
apply the brake pads to the brake disk and create a point of pressure.

MAINTENANCE WORK ON CHASSIS AND ENGINE »
Changing the basic position of the foot brake lever (50 SX Junior)
The basic position of the foot brake lever can be changed by unscrewing screw
[1] and then turning the retainer [2].
Afterwards, check the setting of the rear wheel brake.

Adjusting the control cable on the rear wheel (50 SX Junior)
You should be able to press the foot brake lever 5 to 10 mm (0.2-0.4 in)
before the rear wheel begins to brake.
The brake control cable is adjusted with adjusting screw [3] on the brake anchor
cover. First loosen lock nut [4] and then tighten again.

5-10 mm

After making adjustments, always make sure the wheel turns freely.

min 50 mm

The brake linings must be replaced when the distance between the hub brake
lever and the cable support, measured with the brake lever squeezed, is less
than 50 mm (2 in) (see illustration).
If the brake linings are replaced too late, i.e. when the lining is partly or fully
worn away, the metal shoes will rub against the brake drum, thus reducing
the braking effect and destroying the brake drum.

ENGLISH

Checking the rear brake linings for wear (50 SX Junior)

4
23

Drum brake maintenance (50 SX Junior)
Drum brake maintenance is limited to occasional blowing out of the brake
drum and brake shoes. Brake drum and brake linings can be slightly
roughened with an abrasive tape.

Changing the basic position of the foot brake lever (50 SX) *
The basic setting of the foot brake pedal can be changed by turning the end
stop roller [5]. Using the push rod [6], the free play on the foot brake pedal
must be set.
Measured on the outside, the foot brake pedal must have 3-5 mm of free play,
before the push rod can move the piston in the brake cylinder (to be recognised from the resistance on the foot brake pedal)

3-5 mm
Checking the rear brake fluid level (50 SX)
The reservoir for the rear disk brake is on the right side of the motorcycle on
the rear brake cylinder.
No air bubble should be visible in inspection glass [A] when the vehicle is
parked in a vertical position.

If the brake fluid level drops below the upper edge of the inspection glass,
this indicates that the brake system is either leaking or the brake shoes completely worn.

MAINTENANCE WORK ON CHASSIS AND ENGINE »
Refilling the rear brake fluid reservoir (50 SX) *

Remove the screws [1] and take off the cover [2] and diaphragm [3].The brake
pistons must be pushed back to their basic position. Fill DOT 5.1 brake fluid
(e.g. Motorex Brake Fluid DOT 5.1) up to 10 mm under the upper edge of the
reservoir.
Remount the diaphragm, cover and screws and actuate the foot brake lever
until you feel the point of pressure again. Wipe any overflowing or spilled brake
fluid off with water.

2
3

– Actuate the foot brake lever until you feel the point of pressure again.
– Never use DOT5 brake fluid! It is based on silicone oil and of a
purple color. Seals and brake hoses must be especially adapted to it.
– Store brake fluid out of reach of children.
– Brake fluid can cause skin irritation. Avoid contact with skin and eyes. If
you get brake fluid in your eyes, rinse with plenty of water and consult a
doctor.

ENGLISH

– Don’t let brake fluid get in contact with paint, it is an effective paint remover.
– Use only clean brake fluid taken from a tightly sealed container.

Checking the rear brake pads (50 SX)
The brake pads can be inspected from the rear. The thickness of the linings
may not be less than 1 mm (0.04 in).

min.
1 mm

At their most worn point brake pad linings should not be thinner than 1 mm,
otherwise they could lead to brake failure. For your own safety don’t put off
having your brake pads changed.
If the brake pads are replaced too late so that the lining is partly or entirely
worn, the steel components of the brake pad will rub against the brake disc,
thereby imparing the braking effect and destroying the brake disc.

Replacing the rear brake pads (50 SX) *
5

Dismount the rear wheel (see "Dismounting the rear wheel").
Press the brake shoes apart with a suitable screwdriver to allow the brake
pistons to return to their basic position.
Remove the locking screw [4], unscrew the screw [5] and pull the brake shoes
out of the brake caliper.

Slide new brake shoes into the brake caliper a fasten with the screw [5].
Tighten the screw to 10 Nm and mount the locking screw [4].
Mount the rear wheel and actuate the foot brake lever until you can feel the
pressure point.
– It is very important to keep the brake disk free from oil and fatty matters.
Otherwise, the braking effect would be strongly reduced.
– After assembly, check if circlips have been fitted correctly.
– After working on the braking system, one must always actuate the hand
brake lever or foot brake lever, respectively so as to ensure that the brake
pads will lie against the brake disk and the pressure point is established.

MAINTENANCE WORK ON CHASSIS AND ENGINE »
Removing and mounting the front wheel

Jack the motorcycle up by the frame so that the front wheel is suspended
above the ground.
Undo the hexagon nut [1] and remove it together with the washer.
Hold the front wheel and pull out the wheel spindle [2].
Carefully take the front wheel out of the fork.
– Do not operate the hand brake when the front wheel has been dismounted.
– Make sure the brake disc is always on top when you lay down the wheel,
otherwise the brake disc can be damaged.

– If you don’t happen to have a torque wrench at hand, make sure you have
the tightening torque corrected by a KTM dealer as soon as possible. A
loose axle may lead to an unstable driving behavior of your motorcycle.
– After mounting the front wheel, keep operating the hand brake until the
pressure point returns.
– It is very important to keep the brake disk free from oil and fatty matters,
eitherwise the braking effects would be strongly reduced.

ENGLISH

Lift the front wheel into the fork and correctly position it.
Mount the wheel spindle [2].
Mount the washer and the hexagon nut [1] and tighten 40 Nm.
Put the motorcycle back on the ground and operate the front wheel brake until
the working point is reached.

Removing and mounting the rear wheel
3
4

Prop up the motorcycle under the frame.
Remove hexagon nut [3] on the wheel spindle and disk.
Hold the rear wheel and remove the wheel spindle.
Move the rear wheel forwards, remove chain, lift the rear wheel out of the
swinging fork and remove the brake anchor.
– Do not operate the rear brake when the rear wheel has been dismounted.
– Make sure the brake disc is always on top when you lay down the wheel,
otherwise the brake disc can be damaged (50 SX).

To mount the wheel reverse the procedure described above.
Always hook the brake backing plate into the swing arm support.
Before tightening the hexagon nut of the wheel spindle, ensure that the
supporting plates [4] are resting against the swing arm. Additionally, check
that the rear wheel is aligned with the front wheel.
Tighten the hexagon nut to 40 Nm.
– If you don’t happen to have a torque wrench at hand, make sure you have
the tightening torque corrected by a KTM dealer as soon as possible. A
loose axle may lead to an unstable driving behavior of your motorcycle.
– After mounting the rear wheel, keep operating the rear brake until the pressure point returns (50 SX).
– It is very important to keep the brake disk free from oil and fatty matters,
otherwise the braking effects would be strongly reduced (50 SX).

MAINTENANCE WORK ON CHASSIS AND ENGINE »
Tires, air pressure
Tire type, tire condition, and air pressure level affect the way your motorcycle
rides, and they must therefore be checked whenever you are getting ready to
go anywhere on your motorcycle.
– Tire size can be found in the technical specifications.
– Tire condition has to be checked every time you want to ride your motorcycle. Before leaving, check tires for punctures and nails or other sharp
objects that might have become embedded in them.
– Regularly check the "cold" tire pressure. Correct tire pressure (1.0 bar /
14 psi) guarantees optimum grip and maximum tire life.
– Damaged tires must be replaced immediately to protect your youngster.
– Worn tires can have a negative effect on how the motorcycle performs,
especially on wet surfaces
– Tire pressure below the normal level will lead to premature tire wear.

ENGLISH
26

Checking spoke tension
The correct spoke tension is very important for the stability of the wheels and
thus for riding safety. A loose spoke causes the wheel to become
unbalanced and before long other spokes will have come loose. Check spoke
tension, especially on a new motorcycle, at regular intervals. If necessary, have
the spokes retightened and the wheel centered by a KTM dealer.
– Spokes can tear if you continue to ride with them loose. This may lead to
an unstable handling of your motorcycle.
– Excessively tensioned spokes may rupture due to local overloading. The
spokes must be tensioned to 2.5 - 3 Nm.

Cooling system
The water pump [1] in the engine keeps the cooling liquid in circulation.
The cooling liquid is cooled by the air stream. Therefore, the cooling effect
is reduced when the traveling speed is reduced. Dirty radiators additionally
reduce the cooling effect.
The cooling liquid can be drained by removing screw [2] on the water-pump
cover.

Do not remove any cooler hoses or the drain screw when the engine is hot.

A mixture of 50 % antifreeze and 50 % distilled water is used as the cooling
liquid. How-ever, the antifreeze protection must be at least -25° C (-13° F).
This mixture offers antifreeze protection but also good corrosion protection
and should therefore not be replaced by pure water.
For the cooling system, use only with high-grade antifreeze (Motorex Anti-Freeze).
Using lower-grade antifreeze agents can cause corrosion and coolant
foaming.
Pressure induced by heating of the coolant in the system is controlled by
a valve in the radiator cap [3]; a water temperature rising up to 120° C
(248° F) is admissible without fear of problems.

MAINTENANCE WORK ON CHASSIS AND ENGINE »
Checking coolant level
The coolant should be 10 mm (0.4 in) above the radiator fins when the engine
is cold (see illustr.). In the event of the coolant being drained, always fill and
bleed the system.

10 mm
when engine is cold

If possible, always check level of cooling liquid when engine is cold. If you
have to open the radiator cap when the engine is hot, use a rag to cover the
cap and open slowly to release pressure.

The air filter must be cleaned at intervals depending on the amount of dust
accumulated. To clean the air filter, first remove the seat. Then press both
retaining clips [1], remove the filter holder and the air filter [2]. The air
filter consists of a foam rubber insert soaked with filter oil.

1
1

– Do not clean the foam filter with fuel or petroleum since these will damage the foam. KTM recommends the products (Motorex Liquid Bio Power)
for air filter maintenance.
– Never operate your motorcycle without an air filter. Otherwise, dust and
dirt may get into the engine and lead to increased wear.
– The holder must retain the air filter throughout its entire circumference.
If the filter has been mounted incorrectly, the engine will take in unfiltered air, thereby causing increased engine wear.

2
Thoroughly wash the foam filter in special cleaning fluid (Motorex Bio Dirt
Remover) and allow it to dry well. Only press out the filter, do not wring it out
under any circumstances. Oil the dry foam filter with a high-grade filter
oil ( Motorex Liquid Bio Power). Also clean the air filter box. Check carburetor collar for damage and that it is filled correctly.
Insert the air filter in the opening and fasten it with the filter holder. Then
mount the seat.

Exhaust system *

The silencer is filled with glass-fiber yarn for damping. When in use, the glassfiber yarn becomes loose or coked with oil carbon. This can lead to a power
loss and a reduction of the silencer damping. The glass-fiber yarn packing
can be replaced in a few easy steps.
To replace, remove the silencer from the vehicle and mark the position of the
outer tube [3] to the inner tube [4]. Remove screws [5] and the end cap [6].
Pull of the outer tube and remove the old glass-fiber yarn packing [7] from
the inner tube. Thoroughly clean all parts.

To assemble, mount a new glass-fiber yarn packing onto the inner tube (see
illustration) and slide into the outer tube. Mount end cap and fix with
screws [5]. Before tightening the screws, turn the outer tube until they match
the positions you marked. Mount the silencer and check the exhaust system
for tightness.
Note: Glass fiber yarn packages are offered by your licensed KTM dealer.
The exhaust system becomes very hot while the motorcycle is running. to avoid
burns do not start work on the exhaust system until it has properly cooled
down.

ENGLISH

Cleaning the air filter *

MAINTENANCE WORK ON CHASSIS AND ENGINE »
A

Changing the seat height

The saddle can easily be raised by 25 mm (1 in). This lets you adjust the
height as your child grows.
Figures A and B show the fork and shock absorber positions for a low seat
position. The fork tubes extend approx. 17 mm (0.7 in) (H) above the upper
fork stabilizer. The shock absorber is attached to the upper hole in the frame.
Tighten the clamp screws on the fork stabilizers to 25 Nm (top) and
10 Nm (bottom), the screw on the shock absorber to 45 Nm.

Figures A and B: low seat position
Figures C and D: high seat position

Figures C and D show the fork and shock absorber positions for a high seat
position.Fork tubes are plane with top of upper fork stabilizer. (Screw cap
(Aluminium) protrudes from the top of the upper fork stabilizer)
The shock absorber is attached to the lower hole in the frame. Tighten the
clamp screws on the fork stabilizers to 25 Nm (top) and 10 Nm (bottom), the
screw on the shock absorber to 45 Nm.

ENGLISH

The fork tubes may not be lowered any further than as described above, otherwise the clamping on the upper fork stabilizer will no longer be adequate.

Adjusting the throttle cable *

3-5 mm

There must always be a 3 to 5 mm (0.1 to 0.2 in) play in the throttle cable.
To check this, move back the protective cover [1] on the throttle grip. You
must be able to lift the outer covering of the cable 3-5 mm from the adjusting screw [2], until resistance is felt.
To adjust, loosen the counter nut [3] and turn the adjusting screw accordingly. Finally tighten counter nut and slide the protective cover back on.

1
Adjusting the idle speed Dell’Orto PHVA 14 DS (50 SX Junior) *
The idle speed can be adjusted with screw [4].
The idle speed is increased by turning clockwise.
The idle speed is reduced by turning counter-clockwise.

Adjusting the idle speed Dell’Orto PHBG 19 BS (50 SX) *
The idle speed can be adjusted with screw [5].
The idle speed is increased by turning clockwise.
The idle speed is reduced by turning counter-clockwise.

MAINTENANCE WORK ON CHASSIS AND ENGINE »
Checking the gear oil level
To check the gear oil level, first remove the plug [1]. With the motorcycle parked
in an upright position, a small quantity of oil should flow out of the indicator
opening [2]. If oil must be added, tilt the motorcycle and pour automatic gear
oil (Motorex ATF Super) into the bore.

1
2

Less oil or a poor oil quality lead to premature transmission wear. Therefore,
only use branded products (Motorex ATF Super).

The engine must be warmed up before changing the gear oil. Park the motorcycle on a horizontal surface, remove the oil drain plug [3] and drain the used
oil into an appropriate container. Clean the sealing surface, mount the oil drain
plug together with the gasket and tighten to 15 Nm.

ENGLISH

Changing gear oil *

29
Remove stopper [4] and fill in 0.15 liters of automatic gear oil (Motorex ATF
Super). Mount the stopper and check the engine for tightness.

4
Less oil or a poor oil quality lead to premature transmission wear. Therefore,
only use branded products (Motorex ATF Super).

MAINTENANCE WORK ON CHASSIS AND ENGINE »
Adjusting the centrifugal clutch *
1

1
1
1

ENGLISH

A correctly adjusted centrifugal clutch will provide maximum engine performance and ease of driving and prevent the engine from overheating. Clutch wear
can affect the clutch engagement speed.
The clutch will slip for a longer period of time at higher clutch engagement
speeds, generating more frictional heat and causing the engine to overheat.
If the clutch engagement speed is too low, the engine will not reach the performance range. In both cases, the engine will not seem to have enough power.
Check the clutch engagement speed every 20 hours and correct if necessary
or have it corrected by an authorized KTM workshop.

To tune your clutch, lay the bike on the left side. To prevent oil from leaking
from the transmission vent hose, run the hose upwards and fasten. Remove
the screws [1] and the clutch cover [2] and discard the gasket.
Block the centrifugal clutch [3] with a suitable driver [4].
NOTE: insert the driver through both holes in the primary drive's drum and
gear wheel.
Loosen the nut [5] on the clutch and pull out the driver.
Remove the nut and shim from the crankshaft.

5
30
Screw the extractor (special tool item no. 590.29.021.044) onto the clutch
hub [6] with the M5x50 screws, hold the extractor and remove the centrifugal clutch from the crankshaft by screwing in the extractor screw.
Completely remove the centrifugal clutch, bearings and spacing washers from
the crankshaft.
Loosen the HH screws [7] and remove the clutch shoes [8] from the clutch
hub [6]. Remove the HH screws and bushings [9], the spring sets [10] and
the disks [11] from the clutch shoes.

ADJUSTING THE CLUTCH ENGAGEMENT SPEED:
The spring sets contain 14 spring washers [12] that need to be positioned on
top of each other in the order shown in the illustration [A].
Washers are located between the spring sets and the clutch shoes to pretension the spring sets. You can influence the clutch engagement speed by pretensioning the spring set. 0.5 mm more pretension will increase the clutch
engagement speed by approx. 500 rpm.
The clutch engagement speed is the speed at which the clutch begins to engage
and the motorcycle starts to drive off. The clutch engagement speed is 85009000 rpm for the 50 LC engine.
NOTE: a tachometer (special tool item no. 451.29.075.000) to test the clutch
engagement speed is available from your KTM dealer.

8
11
9
10
7

Make sure the spring sets are not soiled during service or repair work to the
clutch since this can cause them to malfunction.

MAINTENANCE WORK ON CHASSIS AND ENGINE »
10

NOTE: The centrifugal clutch has an outer diameter of approx. 82.5 mm
when new.

11
6

To correct slight wear to the surface, you can insert one of the pretensioning
disks [11] from each clutch spring between the clutch hub and the clutch
shoes – see illustration.
If only one disk is installed, you can go ahead and use it.
The inner diameter of the centrifugal clutch drum may not exceed 84.4 mm
(new condition 84.0 mm).
Assemble in the reverse order.
Apply Loctite 243 to the HH screws [7] and tighten to 12 Nm.
Apply Loctite 243 to the M10x1.25 nut [5] on the crankshaft and tighten to 35 Nm.
Mount a new gasket and position the clutch cover [2].
Screw on the clutch cover with 6 M6x25 screws [1] and tighten to 10 Nm.
Move the transmission vent hose back in the original position.

ENGLISH

CORRECTING CLUTCH WEAR:
Check the clutch shoes for wear. If the surface is only slightly worn you can
remount them again.

TROUBLE SHOOTING »
If you let the specified maintenance work on your motorcycle be carried out, disturbances can hardly be expected. Should an error
occur nevertheless, we advise you to use the trouble shooting chart in order to find the cause of error.
We would like to point out that many operations cannot be performed by oneself. In case of uncertainty, please contact a KTM-dealer.

TROUBLE

CAUSE

REMEDY

Engine fails to start

Operating error

Open fuel tap, replenish fuel, do not use choke

The motorcycle was not driven for a longer The highly inflammable components in modern fuels volatilize
period of time, leaving old fuel in the float if left standing for longer periods of time. If the motorcycle
chamber
has not been used for over 1 week, the fuel should be drained
from the float chamber. The engine will start up immediately
if the float chamber is filled with fresh, ignitable fuel

ENGLISH

Fuel supply interrupted

Close fuel tap, loosen fuel hose at carburettor, lead into a basin
and open fuel tap,
– if fuel leaks out, clean carburettor
– if no fuel leaks out, check tank ventilation, i.e. clean fuel
tap

Electrode distance too large

Reduce electrode distance (0.60 mm)

Plug fouled by oil, wet or bridged

Clean spark plug or renew

Ignition wire or spark plug connector Dismount spark plug, connect ignition cable, hold to ground
(blank place on engine) and actuate kickstarter, a strong spark
damaged
must be produced at the spark plug
– If no spark is produced, loosen spark plug cap from ignition cable, hold about 5 mm from ground and actuate kickstarter
– If a spark now occurs, replace spark plug cap
– If no spark is produced, control ignition system

Kill button wire or short-circuit switch Disconnect black coloured cable from short circuit button at
ignition coil and check ignition spark. If the spark is O.K. repair
faulty
defective part of cable or ignition switch
Loose ignition cable connectors

Inspect cable connectors

Spark too weak

Examine ignition system

Water in the carburetor and jets blocked Dismantle and clean carbureto
Engine without idle running Idle adjusting screw out of adjustment

Less power of engine

Readjust idle running or replace idle adjusting screw

Ignition system damaged

Examine ignition system

Wear

Overhaul engine

Air filter obstructed

Clean or renew airfilter

Fuel supply partly interrupted or blocked Blow through fuel pipe and clean carburetor
Loss of compression due to loose spark Tighten spark plug
plug
Exhaust system damaged

Check exhaust system for damage

Engine has not enough preignition

Check and adjust ignition

Reed paddles tensionless or damaged, sur- Replace reed paddles or reed valve housing
face of reed valve housing damaged
Wear

Overhaul engine

TROUBLE SHOOTING »
TROUBLE

CAUSE

REMEDY

Engine stalling or running Carburetor overflows if level adjust too high, float Clean carburetor, if necessary replace float needle and
with four stroke cycle
needle seating is dirty or enlarged
adjust level

High rpm misfiring

Loose carburetor jets

Tighten jets

Incorrect heat range spark plug or
low quality spark plug

Refer to technical data section

Loose, corroded or non conductive ignition socket Check and seal with silicon
connector

Engine overheating

Engine takes air out of control

Check intake flange and carburettor if firmly setted

Insufficient liquid in cooling system

Top up coolant and bleed cooling system check cooling system for leaks

Radiator fins clogged

Clean radiatar fins with water jet

Frothing in cooling system

Renew coolant using branded anti-freeze/anti-corrosive (Motorex Anti-Freeze)

The motorcycle is being driven too slowly, the clutch Drive the motorcycle faster or reduce the preload on
keeps slipping, causing heat to develop
the clutch springs
Pinched or kinked water hoses

Replace with correct routed hoses

Incorrect ignition timing because of loose stator Readjust to correct ignition timing specifications,
screws
secure screws with Loctite 243
Incorrect compression ratio

Measure and adjust compression ratio

Emission of white smoke Cylinder head or O-ring of cylinder head gasket Check cylinder head, replace O-ring
(steam)
leaks
Excessive oil escapes from Excessive oil quantity in transmission
transmission breather tube

Correct transmission oil level

ENGLISH

Engine spluters into the car- Lack of fuel
Clean fuel pipes, examine tank aeration and clean
buretor
Spark plug with incorrect heat value (Ignition by Fit correct spark plug
incandescence)

CLEANING »
Clean your motorcycle regularly in order to keep its painted finish looking shiny and new.
The best manner would be to use warm water that has been mixed with a commercially available washing detergent and a sponge. The
hard dirt can be removed before with the help of a soft water jet.
Never clean your motorcycle with a high-pressured cleaner or a high-pressured water jet, otherwise the water might run into the electrical components, connectors, sheathed cables, bearings, carburetor etc. and cause mailfunctions, i.e., lead to the premature destruction of these parts.

ENGLISH

– You should use commercially available detergents to clean the motorcycle. Heavily soiled parts should also be cleaned with the
help of a paint brush.
– Before cleaning with water, plug the exhaust pipe to prevent water ingress.
– After the motorcycle has been rinsed with a soft water jet, it should be dried by air pressure and a cloth. Then take a short drive
until the engine has reached its operating temperature, and also operate the brakes. The heat also causes the water at the inaccessible parts of the engine and the brakes to evaporate.
– Slide back the protective covers on the handlebar-mounted instruments so that any water that may have seeped into this part of
the motorcycle is allowed to evaporate.
– After the motorcycle has cooled down, oil and grease all the gliding bearing parts. Also treat the chain with a chain spray.
– To prevent failures in the electric system, you should treat the short circuit button with a contact spray.

STORAGE »
If you want to put your motorcycle away for longer periods of time, please observe the following instructions:
–
–
–
–
–
–
–
–
–
–

Clean motorcycle thoroughly (see chapter: CLEANING)
Change engine oil (old engine oil contains aggressive contaminations).
Check antifreeze and amount of cooling liquid.
the engine warm up again, close fuel tap and wait until the engine dies off by itself. In this way, the carburetor jets are prevented
from becoming resin-clogged by the old fuel.
Remove spark plug and fill in approx. 5 cc of engine oil into the cylinder through the opening. Actuate kickstarter 10 times in order
to distribute the oil onto the cylinder walls and mount the spark plug.
Let fuel flow out of tank into an appropriate basin.
Correct tire pressure.
Lubricate bearing points of the control levers, footrests, etc. as well as the chain.
The storage place should be dry and not be subjected to overly great temperature fluctuations.
Cover the motorcycle with an air permeable tarpaulin or blanket. Do not use airtight materials, as possible humidity might not be
able to escape and thereby cause corrosion.

It would be very bad to let the engine run for a short time during the storage period. The engine would not get warmed up enough and
the thus developed steam would condense during the combustion process and cause the exhaust to rust.

USE AFTER PERIOD OF STORAGE
– Fill up tank with fresh fuel.
– Check motorcycle as before each start (see driving instructions).
– Take a short, careful test ride first.
NOTE: Before you put your motorcycle away for the winter, you should check all parts for their function and wear. Should any service
jobs, repairs, or any refitting be necessary, you should have them carried out during the off-season (lower workload at mechanics'
shops). This way, you can avoid the long waiting times at your shop at the beginning of the next biking season.

TECHNICAL DATA – ENGINE »
ENGINE

50 SX JUNIOR

50 SX

Design

single cylinder 2-stroke engine, with reed valve inlet

Displacement

49.0 cc

Bore/Stroke

39.5 / 40 mm

Fuel

SUPER fuel, research octane no 95, mixed with 2-stroke oil

Oil/gasoline ratio

1 : 60 when using high grade 2-stroke oil (Motorex 2T Cross Power) When in doubt,

Lubrication

mixture lubrication

Crankshaft bearing

2 grooved ball bearing

Connecting rod bearing

needle bearing

Piston pin bearing

needle bearing

Piston rings

1 rectangular ring

Primary drive

straight cut spur gears, 16 : 57 Z

Transmission oil

0.15-0,2 liter automatic gear oil Dexron II (Motorex Topspeed 4T 15W50)

Spark plug

NGK BR 8 ECM

Electrode gap

0.6 mm

Carburetor

Dell’Orto PHVA 14 DS

Air filter

wet foam type air filter insert

Cooling liquid

0.5 litres, 50% antifreeze, 50% distilled water, at least -25 °C (-13 °F)

ENGLISH

please contact your importer

Dell’Orto PHBG 19 BS

35
BASIC CARBURETOR SETTING
Model

50 SX Junior

50 SX

Type

Dell’Orto PHVA 14 DS

Dell’Orto PHBG 19 BS

Main jet

Needle jet

211 FA

260 AU

Idling jet

Jet needle

A10

Needle position from top

Air/Mixture reg. screw open

3.5

3.0

Slide

Starting jet

TIGHTENING TORQUES - ENGINE
Primary gear nut

M14x1,25

40 Nm

Hexagon nut ignition rotor

M10x1,25

20 Nm

Nut of clutch hub

M10x1,25

Loctite 243 + 35 Nm

Cylinder head screws

15 Nm

Cylinder base nuts

18 Nm

Allan head screw-Stator

M5x25

Oil plug

M16

5 Nm

Oil drain plug

M10

15 Nm

Other engine screws

7 Nm

10 Nm

30 Nm

Loctite 243 + 8 Nm

TECHNICAL SPECIFICATIONS - CHASSIS »

ENGLISH
36

CHASSIS

50 SX JUNIOR

50 SX

Frame

single downtube, split-cradle

Fork

Marzocchi Ø = 32 mm

Wheel travel front/rear

140/205 mm (5.5/8 in)

Rear suspension

Central shock absorber WP

Front brake

Disk brake Ø 160 mm (6.4 in)

Rear brake

Drum brake Ø 90 mm (3.5 in)

Disk brake Ø 140 mm (5.5 in)

Tires front

Pirelli 2.50-10 33J Scorpion

Pirelli 60/100-12 36NHS Scorpion

Tires rear

Pirelli 2.75-10 37J Scorpion

Tire pressure

front/rear: 1.0 bar

Fuel tank capacity

1.8 Liters

Final drive ratio

11 : 48

10 : 44

Chain

1/2x3/16“ 96 rolls

1/2x3/16“ 102 rolls

Steering angle

66°

Wheel base

910 mm (35.8 in)

1030 mm (40 in)

Seat height, unloaded

585 mm/610 mm (23/24 in)

650/675 mm (25.6/26.6 in)

Ground clearance

220 mm (8.6 in)

255 mm (10 in)

Rider’s body height

max. 130 cm (51 in)

Rider’s body weight

max. 35 kg (78 lbs)

Recommended age of rider

4-7 years

Engine

50 LC

185/185 mm (7.3/7.3 in)

6-10 years

TIGHTENING TORQUES
Hexagon nuts front/rear axle

M12x1

40 Nm

Hexagon nut swing arm bolt

M10

45 Nm

Clamping screw upper fork bridge

25 Nm

Clamping screw lower fork bridge

10 Nm

Screws handlebar clamp

20 Nm

Shock absorber top/bottom

M10

45 Nm

Allan screw – Handlebar support

M10

Loctite 243 + 40 Nm

Front brake caliper

Loctite 243 + 20 Nm

Front/rear brake disk

Loctite 243 + 15 Nm

Spoke nipple

3 Nm

Other chassis screws

6 Nm

10 Nm

25 Nm

M10

45 Nm

STANDARD-ADJUSTMENT – FORK
Spring

2,0 N/mm

Preload

10 mm (0.4 in)

Fork oil

SAE 7,5

Air chamber length

110 mm (4.3 in)

STANDARD ADJUSTMENT - SHOCK ABSORBER
50 SX Junior
WP 03189D01

50 SX
WP 03189D02

Rebound adjuster

Spring

75 N/mm

35 N/mm

Spring preload

5 mm (0.2 in)

3 mm (0.12 in)

HEAD WORD INDEX »
Page

Page
Adjusting the centrifugal clutch . . . . . . . . . . . . . . . . . .30

Filler cap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

Adjusting the control cable on the rear wheel (50 SX Junior) .23

Foot brake lever . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

Adjusting the idle speed (Dell’Orto PHBG 19 BS) . . .28

Fuel tap

Adjusting the idle speed (Dell’Orto PHVA 14 DS)

General information about KTM disc brakes

. . . . . . .21

Adjusting the throttle cable . . . . . . . . . . . . . . . . . . .28

General Tips and Warnings for starting the motorcycle . .10

Basic suspension setup for the weight of the driver . .18

Hand brake lever

Braking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

How to change the handlebar position

Chain maintenance . . . . . . . . . . . . . . . . . . . . . . . . .20

Important Information for parents about safe driving . . .4

Changing gear oil . . . . . . . . . . . . . . . . . . . . . . . . . .29

Instructions for the first ride . . . . . . . . . . . . . . . . . .10

Changing spring preloading of the shock absorber . . .20

Kickstarter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

Changing the basic position of the foot brake lever

Maintenance work on chassis and engine . . . . . . . . . .16

(50 SX Junior) . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

Operation instruments . . . . . . . . . . . . . . . . . . . . . . . .7

Changing the basic position of the foot brake lever (50 SX) . .23

Periodic maintenance schedule . . . . . . . . . . . . . . . .14

Changing the seat height . . . . . . . . . . . . . . . . . . . . .28

Plugin - Stand (50 SX) . . . . . . . . . . . . . . . . . . . . . . .9

Changing the telescopic fork oil . . . . . . . . . . . . . . . .19

Rebound damping function of the shock absorber . . . .9

Chassis number . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

Refilling the rear brake fluid reservoir (50 SX) . . . . . .24

Check chain tension . . . . . . . . . . . . . . . . . . . . . . . .20

Refueling, fuel . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

Checking and adjusting the steering head bearing

Removing and mounting the front wheel . . . . . . . . . .25

(50 SX Junior) . . . . . . . . . . . . . . . . . . . . . . . . . . . .16

Removing and mounting the rear wheel

Checking and adjusting the steering head bearing

Removing the seat . . . . . . . . . . . . . . . . . . . . . . . . .16

(50 SX) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

Replacing the front brake pads

Checking coolant level

Replacing the rear brake pads (50 SX) . . . . . . . . . . . .24

. . . . . . . . . . . . . . . . . . . . . .27

. . . . . . . . . . . . . . . . . . . . . . . . . . .7
. . . . . . . . . . .17

. . . . . . . . . .25

. . . . . . . . . . . . . . . .22

Checking front brake pads . . . . . . . . . . . . . . . . . . . .22

Running in

Checking rear brake pads (50 SX)

. . . . . . . . . . . . . .24

Serial number locations . . . . . . . . . . . . . . . . . . . . . . .6

. . . . . . . . . . . . . . . . . . . . .26

Setting the basic position and play of the hand brake lever . .21

Checking spoke tension

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

Checking the brake fluid level/ refilling . . . . . . . . . . .22

Short circuit button

Checking the gear oil level

Side stand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

. . . . . . . . . . . . . . . . . . .29

. . . . . . . . . . . . . . . . . . . . . . . . .6

Checking the rear brake fluid level (50 SX) . . . . . . . .23

Starting off

Checking the rear brake linings for wear

Starting when the engine is cold

(50 SX Junior) . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

Starting when the engine is warm

Choke (Dell’Orto carburetor PHBG 19 BS)

. . . . . . . . .8

Stopping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

Choke (Dell’Orto carburetor PHVA 14 DS) . . . . . . . . . .8

Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34

Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34

Technical data – engine . . . . . . . . . . . . . . . . . . . . . .35

Cleaning the air filter

. . . . . . . . . . . . . . . . . . . . . . .27

Technical specifications - chassis . . . . . . . . . . . . . . .36

Cleaning the dust scrabbers of the telescopic fork . . .20

Telescopic fork maintenance . . . . . . . . . . . . . . . . . .19

Cooling system . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

Throttle grip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

Correct chain tension . . . . . . . . . . . . . . . . . . . . . . .20

Tires, air pressure . . . . . . . . . . . . . . . . . . . . . . . . . .26

Driving

To determine the sag of the shock absorber . . . . . . . .18

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
. . . . . . . . . . . . . . .12
. . . . . . . . . . . . . .12

Driving instructions . . . . . . . . . . . . . . . . . . . . . . . . .11

To determine the sag of the telescopic fork

Drum brake maintenance (50 SX Junior)

Trouble shooting . . . . . . . . . . . . . . . . . . . . . . . . . . .32

. . . . . . . . .23

. . . . . . .18

Engine number

. . . . . . . . . . . . . . . . . . . . . . . . . . . .6

What to do when the engine is “flooded”

. . . . . . . . .12

Exhaust system

. . . . . . . . . . . . . . . . . . . . . . . . . . .27

What you should check before each start

. . . . . . . . .11

ENGLISH

. . .28

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

ENGLISH

OWNER’S MANUAL 2008
50 SX JUNIOR
50 SX

*3211222en*
3211222en

3211222en

4/2007
FOTO: MITTERBAUER

KTM Group Partner

KTM-Sportmotorcycle AG
A–5230 Mattighofen
www.ktm.com

Source Exif Data:

File Type                       : PDF
File Type Extension             : pdf
MIME Type                       : application/pdf
PDF Version                     : 1.5
Linearized                      : Yes
Encryption                      : Standard V2.3 (128-bit)
User Access                     : Print, Extract, Print high-res
Page Count                      : 42
Page Mode                       : UseThumbs
Page Layout                     : SinglePage
XMP Toolkit                     : XMP toolkit 2.9.1-13, framework 1.6
About                           : uuid:b3abec67-6d27-4765-a6a2-a4cee63985f4
Producer                        : Acrobat Distiller 6.0.1 (Windows)
Creator Tool                    : PScript5.dll Version 5.2.2
Modify Date                     : 2007:05:23 11:30:36+02:00
Create Date                     : 2007:05:16 12:58:46+02:00
Metadata Date                   : 2007:05:23 11:30:36+02:00
Document ID                     : uuid:d919b9bd-5f53-4012-ad90-0a8a70416804
Format                          : application/pdf
Title                           : 3211222_BA_50_LC_08_EN.qxp
Creator                         : pointlr
Author                          : pointlr

EXIF Metadata provided by EXIF.tools

Ktm 50 Sx Users Manual 3211222_BA_50_LC_08_EN.qxp

50 SX JUNIOR to the manual 68bb7498-2100-a0b4-81af-a5b1736c0eab

Navigation menu

Versions of this User Manual:

Views

Navigation