KTM 125 Operating instructions

Repair manual KTM 125 / 200 Art No 320588 -E
125 / 200
REPAIR MANUAL
ENGINE
KTM SPORTMOTORCYCLE AG
5230 Mattighofen
Austria
www.ktm.at

REPAIR
MANUAL
ENGINE
125/200

1SERVICE-INFORMATIONS
2GENERAL INFORMATION
3REMOVING AND REFITTING ENGINE
4DISASSEMBLING THE ENGINE
5 SERVICING INDIVIDUAL COMPONENTS
6ASSEMBLING THE ENGINE
7ELECTRICAL
8TROUBLE SHOOTING
9TECHNICAL SPECIFICATIONS
10 PERIODIC MAINTENANCE SCHEDULE
11 WIRING DIAGRAMS
12
13
14
15
16

Remove page (s) Replace by page (s) Insert page (s) after page
2-1 2-1C
2-2 2-2C bis 2-3C
2-6 2-5
3-1 3-1C
3-4 bis 3-5 3-4C
5-1 5-1C
5-4 bis 5-5 5-4C bis 5-5C
6-10 bis 6-11 6-10C bis 6-11C
7-1 bis 7-3 7-1C bis 7-13C
9-1 9-1C
9-16 bis 9-28 9-16C bis 9-36C
10-1 10-1C
10-6 10-6C bis 10-9C
11-1 11-1C
11-15 11-15C bis 11-18C
IMPORTANT INFORMATION/UPDATING INSTRUCTIONS
To be able to continue using the existing loose-leaf repair instructions, simply print the
following pages and insert them in the existing repair instructions:
15,17,18,21,23,27,39,43,44,69,70,73-85,91,107-129,135-139,155-158
KTM REPAIR MANUAL IN LOOSE-LEAF FORM
STORING THE REPAIR MANUAL IN THE BINDER
–Put the index into the binder.
–Put the front page of the repair manual (210x297 mm) into the transparent pocket provided for
this purpose on the outside of the binder.
–Put the spine label (170x45 mm) into the transparent pocket provided for this purpose on the
spine of the binder.
–Put the summary list of contents (150x297 mm) into the transparent pocket provided for this
purpose on the inside of the binder or insert this page on the beginning of the manual.
–Then insert the individual chapters of the manual between the sheets of the index according to
the page number printed in the right bottom corner of each page.
Example: page no. 3-5 3 = chapter 3 5 = page 5
All pages with a page number that begins with the digit 3, for example, must be put under the
index heading „Chapter 3“.
–Index sheets that have not been marked with a certain chapter are for your personal convenience.
T
he respective headings can be entered in the list of contents.

EXPLANATION - UPDATING
Edition 11/2002
3.205.74-E Repair Manual 125/200 SX, MXC, EXC
Basicversion Modelyear 1999
(Engine number with first digit “9“)
3/1999
3.205.88-E Updating of Rep.Manual 3.205.74-E
Modelyear 2000/2001
(2000: Engine number with first digit “0“)
(2001: Engine number with first digit “1“)
8/2000
3.210.27-E Updating of Rep.Manual 3.205.74-E
Modelyear 2002
(Engine number with first digit “2“)
7/2001
3.206.005-E Updating of Rep.Manual 3.205.74-E
Modelyear 2003
(Engine number with first digit “3“)
11/2002
Modification / Updating:
Technical Details, Technical Specifications,
Periodic Maintenance Schedule, Wiring Diagrams

INTRODUCTION
This repair manual offers extensiv repair-instructions and is an up-to-date version that describes the
latest models of the series. However, the right to modifications in the interest of technical
improvement is reserved without updating the current issue of this manual.
A description of general working modes common in work shops has not been included. Safety rules
common in the work shop have also not been listed. We take it for granted that the repairs are
made by qualified profesionally trained mechanics.
Read through the repair manual before beginning with the repair work.
 WARNING 
STRICT COMPLIANCE WITH THESE INSTRUCTIONS IS
ESSENTIAL TO AVOID DANGER TO LIFE AND LIMB.
!
CAUTION
!
NON-COMPLIANCE WITH THESE INSTRUCTIONS CAN LEAD
TO DAMAGE OF MOTORCYCLE COMPONENTS OR RENDER
MOTORCYCLES UNFIT FOR TRAFFIC !
„NOTE” POINTS OUT USEFUL TIPS.
Use only ORIGINAL KTM SPARE PARTS when replacing parts.
The KTM high performance engine is only able to meet user expectations if the maintenance work is
performed regularly and professionally.
KTM Austria’s certificate of achievement for its quality system ISO 9001 is the beginning of an
ongoing total reengineered quality plan for a brighter tomorrow.
KTM Sportmotorcycle AG
5230 Mattighofen, Austria
All design and assembly modification rights reserved.
C by KTM SPORTMOTORCYCLE AG, AUSTRIA All rights reserved

REPLY FAX FOR REPAIR MANUALS
We have made every effort to make our repair manuals as accurate as possible but it is always possible for
a mistake or two to creep in.
To keep improving the quality of our repair manuals, we request mechanics and shop foremen to assist us
as follows:
If you find any errors or inaccuracies in one of our repair manual – whether these are technical errors,
incorrect or unclear repair procedures, tool problems, missing technical data or torques, inaccurate or
incorrect translations or wording, etc. – please enter the error(s) in the table below and fax the completed
form to us at 0043/7742/6000/5349.
NOTE to table:
–Enter the complete item no. for the repair manual in column 1 (e.g.: 3.206.005-E).
You will find the number on the cover page or in the left margin on each right page of the manual.
–Enter the corresponding page number in the repair manual (e.g.: 5-7c) in column 2.
–Enter the current text (inaccurate or incomplete) in column 3 by quoting or describing the respective
passage of the text. If your text deviates from the text contained in the repair manual, please write your
text in German or English if possible.
–Enter the correct text in column 4.
Your corrections will be reviewed and incorporated in the next issue of our repair manual.
Item no. of repair manual Page Current text Correct text
Additional suggestions, requests or comments on our Repair Manuals (in German or English):
Name mechanic/shop foreman Company/work shop

GENERAL INFORMATION
Repair manual 125 / 200 Art No 3.206.005-E
OPERATING RANGES OF THE CARBURETOR . . . . . . . . . . . . . . . . . . . . . . . .2-2
CARBURETOR ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-3
BLEEDING OF THE HYDRAULIC CLUTCH . . . . . . . . . . . . . . . . . . . . . . . . . .2-4
OIL PUMP ADJUSTING -
MODELS WITH SEPARATE LUBRICATION . . . . . . . . . . . . . . . . . . . . . . . . . .2-5
CHECK OF EXHAUST CONTROL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-6
INDEX
2-1C
2

Repair manual KTM 125 / 200 Art No 3.206.005 -E
2-2C
main jet
jet needle
jet needle
air control screw
idle adjusting screw
idle jet
throttle valve
Idling range A
Operation with closed throttle valve. This range is influenced by the position of the air control screw 1and the idle adjusting screw
2. Only make adjustments when the engine is hot.
To this end, slightly decrease the idling speed of the engine by means of the idle adjusting screw. Turning it clockwise produces a
higher idling speed and turning the screw counterclockwise produces a lower idling speed. Create a round and stable engine speed
using the air control screw (basic position of the air control screw = open by 1.5 turns and 1,25 on EXE and Supermoto). Then
adjust to the normal idling speed by means of the idle adjusting screw.
Opening up B
Engine behavior when the throttle opens. The idle jet and the shape of the throttle valve influences this range. If, despite good
idling-speed and part-throttle setting, the engine sputters and smokes when the throttle is fully opened and develops its full power
not smoothly but suddenly at high engine speeds, the mixture to the carburetor will be too rich, the fuel level too high or the float
needle is leaking.
Part-throttle range C
Operation with partly open throttle valve. This range is only influenced by the jet needle (shape and position). The optimum
part-throttle setting is controlled by the idling setting in the lower range and by the main jet in the upper range. If the engine runs
on a four-stroke cycle or with reduced power when it is accelerated with the throttle partly open, the jet needle must be lowered by
one notch. If then the engine pings, especially when accelerating under full power at maximum engine revs, the jet needle should
be raised.
If these faults should occur at the lower end of the part throttle range at a four-stroke running, make the idling range leaner; if the
engine pings, adjust the idling range richer.
Full throttle range D
Operation with the throttle fully open (flat out). This range is influenced by the main jet and the jet needle. If the porcelain of the
new spark plug is found to have a very bright or white coating or if the engine rings, after a short distance of riding flat out, a
larger main jet is required. If the porcelain is dark brown or black with soot the main jet must be replaced by a smaller one.
mixture too rich:
too much fuel in proportion to air
mixture too lean:
not enough fuel in proportion to air
1
2

2-3C
Carburetor adjustment
Basic information on the original carburetor setting
The original carburetor setting was adapted for an altitude of approx. 500 meters (1600 ft.) above sea level, and the ambient
temperature of approx. 20° C (68° F), mainly for off-road use and central European premium-grade fuel (125: ROZ 98 / 200: ROZ 95).
Mixing ratio 2-stroke motor oil : super fuel 1:40.
Basic information on a change of the carburetor setting
Always start out from the original carburetor setting. Essential requirements are a clean air filter system, air-tight exhaust system
and an intact carburetor. Experience has shown that adjusting the main jet, the idling jet and the jet needle is sufficient and that
changes of other parts of the carburetor will not greatly affect engine performance.
RULE OF THUMB:
high altitude or high temperatures ➞choose leaner carburetor adjustment
low altitude or low temperatures ➞choose richer carburetor adjustment

WARNING

–O
NLY USE PREMIUM-GRADE GASOLINE (125: ROZ 98 / 200: ROZ 95) MIXED WITH HIGH-GRADE TWO-STROKE ENGINE OIL. OTHER TYPES OF
GASOLINE CAN CAUSE ENGINE FAILURE, AND USE OF SAME WILL VOID YOUR WARRANTY.
–O
NLY USE HIGH-GRADE 2-STROKE ENGINE OIL OF KNOWN BRANDS.
–N
OT ENOUGH OIL OR LOW-GRADE OIL CAN CAUSE EROSION OF THE PISTON. USING TOO MUCH OIL, THE ENGINE CAN START SMOKING AND FOUL
THE SPARK PLUG.
–I
NTHE CASE OF A LEANER ADJUSTMENT OF THE CARBURETOR PROCEED CAUTIOUSLY. ALWAYS REDUCE THE JET SIZE IN STEPS OF ONE NUMBER TO
AVOID OVERHEATING AND PISTON SEIZURE.
NOTE: If despite a changed adjustment the engine does not run properly, look for mechanical faults and check the ignition system.
Basic information on carburetor wear
As a result of engine vibrations, throttle valve, jet needle, and needle jet are subjected to increased wear. This wear may cause
carburetor malfunction (e.g., overly rich mixture). Therefore, these parts should be replaced after 10 000 kilometers (6 000 miles).
Explanation - Example
Compared to the needle NOZ D, the jet needle NOZ F is two steps
leaner in the range from the closed position of the throttle to 1/4
throttle. Otherwise, there are not differences.
Explanation - Example
Compared to the needle R 1467D, the jet needle R 1469D is two steps
leaner in the range from the closed position of the throttle to 1/4
throttle. Otherwise, there are not differences.
NOZ F 0–1/4––
R 1469D 0–1/4––
jet needle throttle valve open effect
NOZ C 0–1/4
NOZ D 0–1/4–
NOZ E 0–1/4– –
NOZ F 0–1/4– – –
NOZ G 0–1/4– – – –
NOZ H 0–1/4– – – – –
NOZ I 0–1/4– – – – – –
jet needle throttle valve open effect
R 1466D 0–1/4
R 1467D 0–1/4–
R 1468D 0–1/4– –
R 1469D 0–1/4– – –
R 1470D 0–1/4– – – –
R 1471D 0–1/4– – – – –

Repair manual KTM 125 / 200 Art No 3.206.005 -E
2-4C
Bleeding of the hydraulic clutch
–Remove screws and take off cover together with rubber bellows.
–At the slave cylinder of the clutch, remove the bleeder nipple 1.
Instead of mount the bleeder syringe 2which is filled with SAE 10
biodegradable hydraulic oil (ex. Shell Naturelle HF-E15).
–Refill oil, until oil is discharged from the bore 3of the master cylinder
in a bubble-free state. Make sure that the oil does not overflow.
! CAUTION !
HAVING COMPLETED THE BLEEDING PROCEDURE, YOU HAVE TO VERIFY THAT THE OIL
LEVEL IN THE MASTER CYLINDER IS CORRECT. FOR FILLING OF THE MASTER CYLINDER,
USE SAE 10 BIODEGRADABLE HYDRAULIC OIL ONLY (EX. SHELL NATURELLE
HF-E15); NEVER USE BRAKE FLUID NOR MIX BIODEGRADABLE HYDRAULIC OILS WITH
MINERAL OILS.
2
1
3

Adjusting oil pump (only with separate lubrication)
NOTE: Prior to adjusting the oil pump, you have to check and, if
necessary, adjust the clearance of the throttle cable.
–Loosen the 3 bolts 1of the oil pump housing and remove the oil
pump cover 2. To make adjustment and control easier, loosen the
bolts of the intake flange 3, remove 4 of them and move the flange
sidewards.
–If the oil pump has been adjusted correctly, the mark Amust coincide
with the notch Bon the cable pulley (except 125 EXE and 125
Supermoto).
–On 125 EXE- and 125 Supermoto-models the notch Bmust coincide
with the edge C.
! CAUTION
!
IFTHE ADJUSTMENT OF THE OIL PUMP IS NOT CORRECT, THE ENGINE IS NOT SUPLIED
WITH THE CORRECT AMOUNT OF OIL AND THIS CAN RESULT IN ENGINE DAMAGE.
–If necessary, loosen the lock nut 4, and correct the adjustment by
turning the adjusting screw 5as required.
–Following the adjustment procedure, the lock nut has to be tightened
again.
–Mount cover 2 and flange 3, tighten the 2 bolts.
2-5C
4
5
1
2
3
A
BB
C