KTM 250 1998 Betriebsanleitung
‘98
7. 97 ART. NR. 3.205.20
250 / 300 / 380
REPARATURANLEITUNG MOTOR
REPAIR MANUAL ENGINE
MANUALE DI RIPARAZIONE MOTORE
MANUEL DE RÉPARATION MOTEUR
MANUAL DE REPARACIÓN MOTOR
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1 General
2 Removing engine / Refitting engine
3 Dismantling engine
4 Servicing on individual components
5 Engine assembly
6 Electrical
7 Trouble shooting
8 Technical data / maintenance schedule
9 Wiring diagrams
(see at the end of this repair manual)
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 DESCIRIPTION 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 TRAI-
NED 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 MOTORCY-
CLES 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 REGU-
LARLY AND PROFESSIONALLY.
FOR TECHNICAL DATA SEE LAST SECTION OF THIS MANUAL. UP-TO-DATE INFORMATION IS PUBLISHED IN OUR UPDATED SPARE PARTS CATA-
LOGUES.
KTM AUSTRIA’S CERTIFICATE OF ACHIEVEMENT FOR ITS QUALITY SYSTEM ISO 9001 IS THE BEGINNING OF AN ON- GOING TOTAL RE-
ENGINEERED QUALITY PLAN FOR A BRIGHTER TOMORROW.
KTM SPORTMOTORCYCLE AKTIENGESELLSCHAFT
5230 MATTIGHOFEN, AUSTRIA
ALL DESIGN AND ASSEMBLY MODIFICATION RIGHTS RESERVED.
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1.0 General
Chap. Component / Component unit Page
1.1 Bleeding the cooling system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-2
1.2 Carburetor adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-2
1.3 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-3
1.3.1 Idling range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-3
1.3.2 Opening up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-3
1.3.3 Part-throttle range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-3
1.3.4 Full throttle range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-3
1.4 Checking the float level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-3
1.5 Checking the setting of the TVC system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-4
1.6 Special tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-5
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1.2 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 (ROZ 95 MOZ). Mixing ratio 2-stroke motor oil : super fuel
1:40 – 1:60.
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 car-
buretor. 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 car-
buretor 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 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.
–NOT 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
N THE 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 malfun-
ction (e.g., overly rich mixture). Therefore, these parts should be replaced after 10000 kilometers (6000 miles).
1.1 Bleeding the cooling system
If the coolant has been drained, the cooling system must be bled as follows after
refilling.
– Make sure that the drain screw 1is fastened.
– Pour approx. 0.5 litres coolant into the system.
– Remove the screw 2on the right radiator and tilt the motorcycle to the right
approx. 30 degree angle.
– Now pour coolant into the system until it escapes from the right radiator free of
bubbles and replace the screw 2immediately so that no more air may reach the
right radiator.
– Return the motorcycle to its original position and top up the left radiator until
the coolant can be seen approx. 10 mm above the radiator fins.
– Check the coolant level again after a short ride.
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1.3 Definitions
Mixture too rich:
Too much fuel in proportion to air.
Mixture too lean:
Not enough fuel in proportion to air.
1.3.1 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 increase the idling speed of the engine by means of the idle adju-
sting 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). Then adjust to the normal idling speed by means of the idle adju-
sting screw.
1.3.2 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 carbu-
retor will be too rich, the fuel level too high or the float needle is leaking.
1.3.3 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 engi-
ne 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-stro-
ke running, make the idling range leaner; if the engine pings, adjust the idling range
richer.
1.3.4 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.
Explanation - Example
Compared to the needle N 85 A, the jet needle N 85 C is two steps leaner in the
range from the closed position of the throttle to 1/4throttle. Otherwise, there are
not differences.
1.4 Checking the float level
Arrange the Keihin carburetor diagonally at about 60° so that the spring in the float
needle valve is not pressed together. In this position, the edge of the float should be
parallel with the float chamber sealing surface (see illustration).
jet needle throttle valve open effect
N 85 A
N 85 B 0–1/4–
N 85 C 0–1/4––
N 85 D 0–1/4– – –
N 85 E 0–1/4– – – –
NOZ E
NOZ F 0–1/4–
NOZ G 0–1/4– –
NOZ H 0–1/4– – –
NOZ I 0–1/4– – – –
N 85 C 0–1/4––
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main jet
jet needle
jet needle
air control screw
idle adjusting screw
idle jet
throttle valve
60°
1.5 Checking the setting of the TVC system
NOTE: THE FUNCTION OF THE TVC SYSTEM IS CHECKED WITH THE ENGINE RUNNING.
THIS TEST CHECKS THE START OF ADVANCE AND THE END OF ADVANCE.
– For this, remove the left control cover.
– Connect a rev counter (either to the ignition cable or to the blue/white cable in
the electronics box, depending on the rev counter design).
– Start engine, accelerate gently and observe when the TVC system starts to advan-
ce (tooth segment creeps upwards).
START OF ADVANCE:END OF ADVANCE:
250: at 5400 rpm at 7550 rpm
300: at 5300 rpm at 7400 rpm
380: at 5200 rpm at 7200 rpm
– If necessary, turn the adjusting screw 1.
NOTE: TWISTING THE ADJUSTING SCREW IN DELAYS THE COMMENCEMENT OF ADJUSTMENT BY
THE TVC SYSTEM, TWISTING THE ADJUSTING SCREW OUT MEANS THAT THE TVC SYSTEM WILL
PERFORM THE ADJUSTMENT EARLIER.
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FIG. PARTNO. DESCRIPTION
1 560.12.001.000 REPAIR STAND ‘96
3 546.29.003.000 HOLDING PLATE 250
4 560.12.004.000 GEAR WHEEL SEGMENT
5 546.29.009.044 PULLER FOR FLYWHEEL
6 6 276 807 PULLER FOR FLYWHEEL
7 510.12.011.000 SPECIAL CIRCLIP PLIER
8 544.12.012.000 HOLDING SPANNER FOR FLYWHEEL SEM
9 510.12.014.000 TIMING DEGREE DISC
10 510.12.016.000 PROTECTION CAP
11 546.29.012.000 HOLDING SPANNER FOR FLYWHEEL KOKUSAN
13 501.12.013.000 DIAL GAUGE
14 501.12.030.000 DIAL GAUGE SUPPORT
16 6 899 785 LOCTITE 242 BLUE
17 151.12.017.000 BEARING PULLER
18 151.12.018.100 INTERNAL BEARING PULLER 18 - 23 MM
18 151.12.018.000 INTERNAL BEARING PULLER 12 - 16 MM
18 151.12.018.200 INTERNAL BEARING PULLER 5 - 7 MM
19 546.29.027.000 RIVETTING TOOL
25 0276 179 000 EXTRACTOR PRIMARY GEAR
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18
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10
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25
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8
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1.6 Special tools
– Notices –
2.1 Removing the engine
– Thoroughly clean the motorcycle.
– Use a suitable supporting device to jack up the motorcycle.
– Remove the seat and the tank with the spoilers.
– Drain the cooling liquid.
– Remove the exhaust system and the engine brace.
– Disconnect the radiator hoses at the engine.
– Remove the carburetor.
– Remove the engine sprocket cover and the chain.
– Disconnect the electrical wires.
– Unhook the clutch cable from the clutch lever.
– Undo the three screws 1and remove the compensation chamber 2of KTC
system including O-ring.
– Undo the engine mounting screws.
– Remove the swingarm pivot and pull the swingarm backwards.
– Lift the engine out of the frame on the left side.
NOTE: THE ENGINE NEED NOT BE REMOVED TO REMOVE THE CYLINDER HEAD AND THE CYLINDER.
IT IS ALSO POSSIBLE TO WORK ON THE CLUTCH, THE PRIMARY DRIVE AND THE SHIFT MECHA-
NISM WITHOUT PREVIOUSLY REMOVING THE ENGINE.
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2.0 Removing engine / Refitting engine
Chap. Component / Component unit Page
2.1 Removing engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-1
2.2 Refitting engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-2
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Dieses Handbuch passt für folgende Modelle
2
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