KTM 250 1998 Repair Manual Download Page 46

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TROUBLE

Engine has not enough power

Engine revs not high and run-
ning with four stroke cycle

High rpm misfiring

Engine spluters into the carbu-
retor

Engine overheating

Emission of white smoke
(steam)

Excessive oil escapes from
transmission breather tube

All switched on lamps blown
out

CAUSE

Reed paddles tensionless or damaged,
surface of reed valve housing damaged

Wear

Electronical ignition timing faulty

Carburetor overflows if level adjust too
high, float needle seating is dirty or
enlarged

Loose carburetor jets

Incorrect heat range spark plug or
low quality spark plug

Incorrect or faulty spark plug connector

Loose, corroded or non conductive
ignition socket connector

Lack of fuel

Spark plug with incorrect heat value
(Ignition by incandescence)

Engine takes air out of control

Insufficient liquid in cooling system

Cooling system not or insufficiently
bleeded

Radiator fins clogged

Frothing in cooling system

Pinched or kinked water hoses

Incorrect ignition timing because of
loose stator screws

Incorrect dimension ,,X“

Cylinder head or O-ring of cylinder
head gasket leaks

Excessive oil quantity in transmission

Water pump shaft seal ring or right-
hand crankshaft seal ring defect

Silicon O-rings of control roller or of
control flap leaks

Voltage regulator faulty

REMEDY

Replace reed paddles or reed valve housing

Overhaul engine

Have ignition system checked

Clean carburetor, if necessary replace float needle and adjust level

Tighten jets

Refer to technical data section

Test and/or replace spark plug connectors correct type

Check and seal with silicon

Clean fuel pipes, examine tank aeration and clean

Fit correct spark plug

Check intake flange and carburettor if firmly setted

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

Bleed cooling system (see operating instructions)

Clean radiatar fins with water jet

Renew coolant using branded anti-freeze/anti-corrosive

Replace with correct routed hoses

Readjust to correct ignition timing specifications, secure screws pro-
perly with Loctite 242

Measure and adjust to correct specification

Check cylinder head, replace O-ring

Correct transmission oil level

Replace shaft seal ring and change gear oil, check coolant

Replace O-rings

Control connections of voltage regulator. Check voltage regulator

Summary of Contents for 250 1998

Page 1: ... 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 ...

Page 2: ...emoving 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 ...

Page 3: ... 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 ...

Page 4: ...oling 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 ...

Page 5: ...OW GRADE OIL CAN CAUSE EROSION OF THE PISTON USING TOO MUCH OIL THE ENGINE CAN START SMOKING AND FOUL THE SPARK PLUG IN 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 S...

Page 6: ...n 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 run...

Page 7: ...ronics 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 ...

Page 8: ... 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 R...

Page 9: ... Notices ...

Page 10: ...h cable from the clutch lever Undo the three screws 1 and remove the compensation chamber 2 of 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 DR...

Page 11: ...es Mount the chain and the engine sprocket cover Mount the carburetor Connect the radiator hoses to the engine and fill the cooling system with a mix ture of 40 antifreeze and 60 water Mount the exhaust system Mount the tank with the spoilers and the seat Start the engine and bleed the cooling system Warm up the engine and check if the TVC system is properly adjusted Check the electrical system fo...

Page 12: ...cover 3 3 3 4 Clutch linings 3 3 3 5 Primary drive 3 3 3 6 Kickstarter 3 4 3 7 Shifting mechanism 3 4 3 8 Ignition Kokusan 3 4 3 9 Ignition SEM 3 5 3 10 Clutch release shaft 3 5 3 11 Engine sprocket 3 5 3 12 Intake flange reed valve housing 3 5 3 13 Parting of engine case 3 6 3 14 Shift mechanism transmission 3 6 3 15 Crankshaft 3 6 ...

Page 13: ...l to drain 3 2 Cylinder head cylinder piston Unscrew the 6 M8 collar screws Remove cylinder head and the two O rings Undo the screws and remove the left control cover 2 together with the gasket Undo the screws and remove the right control cover 3 together with the gasket Remove the securing clip of the ball socket 4 and unhook the ball socket 5 from the adjusting lever Remove the 4 collar nuts on ...

Page 14: ...tch discs Loosen collar screws in diagonally opposite sequence to prevent wedging of discs as springs expand Remove collar screws springs and spring retainer Remove the pressure cap and pull out the clutch push rod together with the thrust bearing Take the disc package out of the outer clutch hub 3 5 Primary drive Block the primary gear with the gear wheel segment 4 see illustration Undo the hexag...

Page 15: ...th a screw driver so it no longer engages with the driver for the shaft roller at the same time remove shift shaft from the housing NOTE WATCH THE STOP DISC WHICH REMAINS IN THE HOUSING Remove allan head screw and take driver for roller 5 and locking piece 6 from the shift roller Disassemble locating lever 7 only if the engine case must be replaced Remove allan head screw 8 and locking lever with ...

Page 16: ...ar srews and remove base blate 3 10 Clutch release shaft Unhook clutch cable Remove collar screws and retaining bracket 1 Unscrew screw 2 Turn clutch release shaft approx 70 degrees anti clockwise and pull out of housing 3 11 Engine sprocket Remove circlip from countershaft using circlip pliers Slide off engine sprocket distance bushing and O ring 3 12 Intake flange reed valve housing Remove the 5...

Page 17: ...Pull the shift roller 3 out of the bearing seat Remove the shift forks NOTE ALTHOUGH THE COUNTER SHAFT SHIFT FORKS ARE IDENTICAL THEY SHOULD BE REFITTED IN THE SAME POSITION AS BEFORE IF REUSED THEREFORE MARK ACCORDINGLY UPON REMOVAL Push drive shaft 4 approx 30 mm upwards and remove countershaft 5 It is then possible to remove the mainshaft completely from bearing NOTE WATCH COUNTERSHAFT STOP DIS...

Page 18: ...e generator Kokusan 4 11 4 21 Ignition SEM 4 12 4 21 1 Spark plug NGK BR 8 ECM 4 12 4 21 2 Check stator SEM 4 12 Engine housing NOTE READ THROUGH THE FOLLOWING SECTION BEFORE COMMENCING WORK THEN DETERMINE THE ASSEMBLY SEQUENCE SO THAT THE ENGINE HOUSING HALVES ONLY NEED TO BE HEATED UP ONCE BEFORE REPLACING THE BEARINGS HAVING FIRST REMOVED THE DOWELS IN ORDER TO EXPEL THE BEARINGS OR REMOVE THEM...

Page 19: ... knocking the hou sinq half on a plane piece of wood when the housing has a temperature of 150 C If necessary use a 6 mm internal bearing extractor and guide hammer see illustra tion Press in new grooved ball bearing to the stop BEARING BOLT KICKSTARTER INTERMEDIATE GEAR 8 Experience has shown that it is never necessary to replace the bearing bolt It is not recommended to mount a used bearing bolt...

Page 20: ...ring falls out of its seat of its own accord when housing half has been hea ted to approx 150 C If necessary knock housing half on a plane piece of wood Press in new grooved ball bearing to the stop NEEDLE BUSHING OF SHIFT SHAFT 5 Remove shaft seal ring and press old needle bushing inwards Press in new needle bushing from the outside to the collar D CRANKSHAFT SEAL RING 6 Press in new crankshaft s...

Page 21: ...moved with a fine abrasive stick 2 PISTON RING GROOVES The piston rings must not get jammed in the grooves For cleaning the grooves use an old piston ring or abrasive paper grain size 400 3 THE PISTON RING LOCATING PINS must be firmly seated in the piston and must not be worn out 4 Check PISTON RINGS for wear and check end gap 4 5 Piston ring end gap Insert pisto ring into the cylinder and adjust ...

Page 22: ...icon O rings 6 on control flap and grease Mount bearing sleeves 4 and gear segments 3 mount gear segment with cylin der pin on right hand side Turn control rollers 2 in cylinder in such a way that ports are completely open and no edges protrude Place control flap 5 in cylinder engage gear segments in control rollers in such a manner that when the control flap is open pivoted right to the top the m...

Page 23: ...GE BALL HEADS bl for clearance Remove CIRCLIP bm and check AXIAL BEARINGS bp and WASHERS for signs of wear If the WATER PUMP SHAFT SEAL RING bn is replaced it should be coated with Loctite 242 on the outside Check GROOVED BALL BEARING bo for clearance 4 11 Preassembly of clutch cover Grease water pump shaft seal ring bn and mount centrifugal timer 9 Fit adjusting spring 3 auxiliary spring 4 and cu...

Page 24: ...eedle 9 out of the kickstarter shaft KICKSTARTER SHAFT 4 Check for signs of wear and damage 4 14 Assemble of kickstarter shaft Fix the kickstarter shaft 4 in a vice with the toothed end upwards use covered vice clamps Mount ratchet spring 5 on kickstarter shaft as shown in the illustration Place needle cage 6 in position push starter gear over it pressing locking pawl 3 inwards so that starter gea...

Page 25: ...PERATION OF GEAR CHANGE Carefully clean components and replace damaged components NOTE ALWAYS PLACE CIRCLIPS WITH SHARP EDGE FACING THE COMPONENTS SECURED ENSURING THAT THEY ARE NOT OVEREXPANDED USE SPECIAL PLIERS CHECK THAT AFTER ANY REPAIR OF THE TRANSMISSION CIRCLIPS SHOULD AXIALLY NOT MOVE MORE THAN 0 2 MM 0 006 IN AND MUST NOT SEIZE BETWEEN STOP DISCS 4 15 2 Assemble countershaft Fix counters...

Page 26: ...ween lining disc and pressure cap for signs of mecha nical damage OUTER CLUTCH HUB bl Check start surfaces D of clutch discs on for wear If indentations exceed 0 5 mm 0 02 in replace outer clutch hub see below Mount inner ring 7 and needle cage 8 and check for clearance 4 17 Replace outer clutch hub Drill open the clutch rivets bm in area of retaining bracket bn and remove parts Check 8 absorbing ...

Page 27: ...o be more than 0 7 mm 0 03 in BALL BEARINGS bl Check ball bearings for easy movement SHIFT MECHANISM Assemble shift mechanism see below and check free play between slide plate 3 and shift quadrant 4 Free play should be 0 4 0 8 mm 0 016 0 032 in 4 19 Preassembly of shift shaft Fix shift shaft in vice at shorter end use covered clamps Mount slidie plate 3 with guide pins downwards hook guide pins in...

Page 28: ... 0 60 MM 0 024 IN INSULATOR Check for cracks and fissures CAUTION ALWAYS USE A SPARK PLUG WITH RESISTOR OTHERWISE PROBLEMS CAN OCCUR IN THE CDI UNIT 4 20 2 Check stator and pulse generator Kokusan Use an ohmmeter to perform the following measurements NOTE THE MEASURING MUST BE PERFORMED AT A TEMPERATURE OF 20 C OTHERWISE SIG NIFICANT DEVIATIONS MUST BE EXPECTED REPLACE THE STATOR IF THE MEASURED V...

Page 29: ...forming measurements 4 21 1 Spark plug NGK BR 8 ECM Set the electrode distance ELECTRODE DISTANCE 0 60 MM 0 024 IN INSULATOR Check for cracks and fissures CAUTION ALWAYS USE A SPARK PLUG WITH RESISTOR OTHERWISE PROBLEMS CAN OCCUR IN THE CDI UNIT 4 21 2 Check stator SEM Perform the following measurements with an ohmmeter NOTE THE MEASURING MUST BE PERFORMED AT A TEMPERATURE OF 20 C OTHERWISE SIG NI...

Page 30: ...rive clutch 5 4 5 8 Clutch discs pressure cap 5 5 5 9 Clutch cover 5 5 5 10 Piston cylinder 5 6 5 11 Adjust dimension X 5 6 5 12 Adjust control flap dimension Z 5 6 5 13 Cylinder head 5 7 5 14 Reed valve intake flange 5 7 5 15 Left hand side cover 5 8 5 16 Chain sprocket 5 8 5 17 Mounting ignition Kokusan 5 8 5 18 Mounting ignition SEM 5 8 5 19 Adjusting ignition point SEM 5 9 5 20 Filling with ge...

Page 31: ... the mainshaft Mount the two other shift forks 2 at the countershaft using the marks applied before disassembly for better orientation CAUTION USED SHIFT FORKS SHOULD BE MOUNTED IN THE SAME SLIDING GEAR AS BEFORE WATCH AT THE MARKINGS FROM DISMANTLING Hook shift forks in the sliding gears Insert shift rails in shift forks short rail towards mainshaft and jointly pivot side ways see illustration Pr...

Page 32: ...use it to fix the clutch release lever spring 5 5 Shift mechanism Place locating spring with bent leg upwards into engine housing Insert collar sleeve 3 into spring with collar upwards Coat collar screw 4 with Loctite 242 Insert locating lever with roll upwards and fix all parts with collar screw Hook locking spring 5 to lever Mount roller locking device plastic part to shift roller Ensure that th...

Page 33: ...Put the oiled O ring onto the crankshaft and mount the distance bushing with the chamfer facing the crank web Insert woodruff key into crankshaft Place primary gear onto crankshaft with collar downwards Apply Loctite 242 to thread Fit locking washer and hexagon nut left hand thread by hand Put the inner ring onto the main shaft with the collar facing downwards then mount the oiled needle cage 3 Mo...

Page 34: ...Tighten the collar screws crosswise Do not apply more than 6 Nm 4 5 ft lb to prevent damaging of the threads in the inner clutch hub 5 9 Clutch cover Check whether both dowels are mounted in clutch cover or engine housing Grease kickstarter shaft seal ring and position clutch cover gasket Secure gasket with a little grease Carefully position preassembled clutch cover and press into place turning c...

Page 35: ... ON THE OTHER HAND IF THE DIMENSION X IS TOO SMALL THE ENGINE WILL PING AND OVERHEAT Place slide caliper on cylinder and use feeler gauge to measure distance between piston and slide caliper DIMENSION X 0 MM 0 1 MM 0 004 IN Tighten the collar nuts at the cylinder base with 35 Nm 26 ft lb 5 12 Adjusting control flap dimension Z NOTE DIMENSION Z IS THE DISTANCE FROM THE LOWER EDGE OF THE CONTROL FLA...

Page 36: ... again and fit gasket for control cover Refit ball socket and fit safety device Secure gasket with grease and fit control cover 7 5 13 Cylinder head Clean cylinder and cylinder head sealing surface place O rings in grooves Mount cylinder head with water nozzle on the exhaust side Mount the collar screws with new copper gaskets and tighten them crosswise taking three turns to achieve the total tigh...

Page 37: ... 3 screws and fix the stator Turn the stator so that mark A on the stator coincides with mark B in the hou sing Then tighten the three screws of the stator Mount the rotor Mount the detent edged ring and the nut Hold the rotor with the holding spanner and tighten the nut with 60 Nm 45 ft lb Hook the clutch cable onto the clutch release lever Mount the gasket and fix the ignition cover with 5 colla...

Page 38: ...y remove flywheel to prevent further turning of stator Tighten the three stator cylinder screws Mount flywheel and tighten collar nut with 60 Nm 45 ft lb Check ignition point once more Remove dial gauge and fit spark plug with OR Hook clutch cable to release lever Mount gasket and fix ignition cover with 5 collar screws 5 20 Filling in gear oil Mount oil drain screw with new gasket and tighten Fil...

Page 39: ... Notices ...

Page 40: ...ecking voltage regulator Tympanium 6 2 6 2 Checking voltage regulator rectifier Shindengen 6 2 6 3 Checking voltage regulator Kokusan 6 2 6 4 Checking capacitor 6 3 6 5 Ignition coil SEM 6 3 6 6 Ignition coil Kokusan 6 3 6 7 CDI unit 6 3 Wiring diagramms Cap 9 ...

Page 41: ...ded either If the reading significantly deviates from the nominal value replace the voltage regu lator 6 2 Checking the voltage regulator rectifier Shindengen Start the engine and switch on the low beam Connect a voltmeter to the two terminals of the capacitor red white cable positive brown cable negative Accelerate the engine to a speed of 5000 r p m and read off the voltage NOMINAL VALUE 14 0 15...

Page 42: ...TH THEIR MARKINGS CONNECT RED WHITE CABLE TO TERMINAL 6 5 Ignition coil SEM As this ignition coil uses electronic components you are advised not to use con ventional measuring instruments An accurate function test can only be carried out on an ignition test bench 6 6 Ignition coil Kokusan Disconnect all cables and remove the spark plug connector Use an ohmmeter to measure the following values NOTE...

Page 43: ... Notices ...

Page 44: ...7 1 7 0 Trouble shooting Cap Component Component unit Page 7 1 Trouble shooting 7 2 ...

Page 45: ...asin and open fuel tap if fuel leaks out clean carburettor if no fuel leaks out check tank ventilation i e clean fuel tap Reduce electrode distance 0 60 mm Clean spark plug or renew Dismount spark plug connect ignition cable hold to ground blank place on engine and actuate kickstarter a strong spark must be pro duced at the spark plug If no spark is produced loosen spark plug cap from ignition cab...

Page 46: ...head or O ring of cylinder head gasket leaks Excessive oil quantity in transmission Water pump shaft seal ring or right hand crankshaft seal ring defect Silicon O rings of control roller or of control flap leaks Voltage regulator faulty REMEDY Replace reed paddles or reed valve housing Overhaul engine Have ignition system checked Clean carburetor if necessary replace float needle and adjust level ...

Page 47: ... Notices ...

Page 48: ...sembly clearance 8 3 8 1 2 Tightening torques engine 8 3 8 1 3 Gasket thicknesses 8 3 8 1 4 Basic carburetor setting 8 3 8 2 Technical data engine only USA 8 4 8 2 1 Tolerance assembly clearance 8 5 8 2 2 Tightening torques engine 8 5 8 2 3 Gasket thicknesses 8 5 8 2 4 Basic carburetor setting 8 5 8 3 Maintenance schedule 8 6 ...

Page 49: ...0 6 mm 0 024 in Dimension Z 48 mm 1 9 in 46 mm 1 7 in 50 5 mm 1 99 in TVC start open 5400 min 5300 min 5200 min TVC fully open 7550 min 7750 min 7200 min Primary drive straight cut spur gears primary ratio 25 72 straight cut spur gears primary ratio 26 72 Clutch multiple disc clutch in oil bath Transmission 5 speed claw actuated Gear ratio 1 st Gear 15 29 15 29 15 29 15 29 2 nd Gear 17 27 18 26 18...

Page 50: ... 20x1 5 80 Nm 60 ft lb Other screws M 6 10 Nm 8 ft lb M 8 30 Nm 21 ft lb M 10 50 Nm 36 ft lb Crankcase 0 5 mm Clutch cover 0 5 mm Cylinder bottom gasket as required Available cylinder bottom gaskets 0 2 0 4 0 5 0 7 mm Cylinder head gasket O rings T A B L E 3 8 5 BASIC CARBURETOR SETTING Carburetor Carburetor setting number Main jet Idling jet Starting jet Jetneedle Needle position from top Throttl...

Page 51: ...n 50 5 mm 1 99 in TVC start open 5400 min 5300 min 5200 min TVC fully open 7550 min 7750 min 7200 min Primary drive straight cut spur gears primary ratio 25 72 straight cut spur gears primary ratio 26 72 Clutch multiple disc clutch in oil bath Transmission 5 speed claw actuated Gear ratio EXC M XC EXC MXC 1 st Gear 15 29 15 29 15 29 15 29 15 29 15 29 15 29 2 nd Gear 17 27 18 26 18 26 18 26 18 26 1...

Page 52: ...x1 5 100 Nm 75 ft lb Crankcase and cover bolts M 6 8 Nm 6 ft lb Swingarm pivot M 14 100 Nm 103 ft lb Collar nut rear wheel spindle M 20x1 5 80 Nm 60 ft lb Other screws M 6 10 Nm 8 ft lb M 8 30 Nm 22 ft lb M 10 50 Nm 37 ft lb Crankcase 0 5 mm Clutch cover 0 5 mm Cylinder bottom gasket as required Available cylinder bottom gaskets 0 2 0 4 0 5 0 7 mm Cylinder head gasket O rings T A B L E 3 8 5 BASIC...

Page 53: ...lutch 125 200 Check telescopic fork action Check telescopic fork for leaks Slide up dust scrabbers of telescopic fork and remove dirt Clean dust scrabber of telescopic fork WP Extreme fork Loosen the bleeding screws of telescopic fork Change oil of telescopic fork Service telescopic fork completely Check steering head bearing free play Clean and regrease steering head bearing Check setting and dam...

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Page 59: ... C Y C L E A G A 5 2 3 0 M a t t i g h o f e n P o s t f a c h 9 1 A u s t r i a I n t e r n e t h t t p w w w k t m c o a t F N 1 0 2 0 1 9 d L a n d e s g e r i c h t R i e d i m I n n k r e i s ART NR 3 205 20 250 300 380 98 ...

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