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TM RACING 250 EN, Workshop Manual

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TM RACING 250 EN Workshop Manual Download Page 63

59

1

2

3

4

5a

5a

5b

5a

5c

7

6

ENGINE DISASSEMBLY

2.22  SEMICASE

Remove  the  heating  unit  as  described  in  the  relevant 

paragraph.

Remove  all  parts  on  the  flywheel  side  and  transmission 
side as described in the relative paragraphs.

2.22.1  

Opening

On the transmission side, remove the gearbox secondary shaft locking see

-

ger (1). 

Unscrew the screws (2) 

M6 x 50

 and the screw (3) 

M6 x 35

. 

Turn the engine on the ignition side and remove the countershaft (4).  

Undo the screws (5).

5a = M6 x 50

5b = M6 x 35

5c = M6 x 60

With a rubber hammer open the two split crankcases (6) and (7). 

Summary of Contents for 250 EN

Page 1: ...www tmracing it Ed 01 03 2020 250 300 Mx En Smx Smr 2019 Workshop Manual 2 STROKE ENGINE...

Page 2: ......

Page 3: ...UR HANDS THOROUGHLY AFTER HANDLING THE OIL WEAR LATEX GLOVES OR EQUIVALENT DURING MAINTENANCE WORK ON THE MOTORCYCLE OIL IS HIGHLY POLLUTANT THEREFORE AFTER USE IT MUST BE DISPOSED OF AT SPECIAL COLLE...

Page 4: ...start E S as well as kick start K S MX SMX models have K S as standard and may be equipped with E S as an option Please make a note of your motorcycle s serial numbers in the boxes below When it is n...

Page 5: ...cylinder 24 2 8 6 Piston replacement with cylinder to be machined 25 2 8 7 Cylinder replacement 25 2 8 8 Cylinder and piston re mounting 25 2 9 Checking the squish 26 2 10 Drain valve removal revision...

Page 6: ...COUNTER GEARS 52 2 20 1 Gears removal 52 2 20 2 Reassembly of gears 53 2 21 GEARBOX CONTROL SHAFT AND RATCHETS HOLDER REMOVAL 55 2 22 SEMICASE 59 2 22 1 Opening 59 2 22 2 Re assembly 60 2 23 CRANKSHAF...

Page 7: ...supports 2 roller bearings Small end bearing silvery needle roller cage Big end bearing needle roller cage Piston forged in light alloy Segments 2 segments GAP 0 60 0 65 Gearbox oil quantity 700 cc Pr...

Page 8: ...ents GAP 0 60 0 65 Gearbox oil quantity 700 cc Primary transmission straight toothed gears 19 57 Clutch multiple disc oil bath Gearbox with front couplings 5 gears Gear ratios 1a 14 28 2a 17 25 3a 19...

Page 9: ...Clutch hub nut M18x1 5 Loctite 243 80 Nm Clutch springs Allen screw M 6 10 Nm Ignition stator Allen screw M 6 Loctite 243 10 Nm Limit switch plate fixing countersunk screw M 6 10 Nm Allen screw for ge...

Page 10: ...n wear Fully change piston Check exhaust valve actuator play Exhaust valves replacement Fully change conrod Check clutch discs Check clutch springs Check transmission and gearbox Mixer oil pump replac...

Page 11: ...essive play between cylinder and piston Replace 2 Segments or their housing in the piston worn Replace 3 Excessive accumulation of carbon deposits in the combustion chamber or on the piston crown Clea...

Page 12: ...oosened Tighten 4 Excessive distance between spark plug electrodes Adjust 5 Insufficient compression Check the cause 6 Reed valve pack plates broken Replace The engine overheats 1 Combustion chamber a...

Page 13: ...9 1 ADJUSTMENTS REPLACEMENTS...

Page 14: ...urfaces replace the aluminium washers 2 and 4 remove any magnetic debris 5 of the drain cap 3 and screw the cap back on tightening to 20 Nm 2 kgm 14 75 ft lb Prepare a measure with the amount of the p...

Page 15: ...RD CLUTCH REPLACEMENT Drain the engine oil as described in the relative paragraph Unscrew the M5 L75 1 and M5 L25 2 screws then remove the clutch cover 3 Remove the gasket 4 Unscrew the screws 5 of th...

Page 16: ...ure plate 8 is present and remove it Use two sticks to pry up and remove the discs 9 NOTE On re mounting the new discs 9 lubricate them with engine oil and make sure that the first disc mounted is lin...

Page 17: ...with a torque of 8 Nm 0 8 kgm 5 9 ft lb Check that the gasket 4 is not ruined otherwise replace it and mount it on the guard Mount the clutch guard 3 and tighten the screws 1 and 2 gradually with a t...

Page 18: ...14 ADJUSTMENTS REPLACEMENTS...

Page 19: ...15 2 ENGINE DISASSEMBLY...

Page 20: ...1 9 ENGINE DISASSEMBLY 2 1 ENGINE COMPONENTS LAYOUT MX SMX 1 Cylinder head 2 Cylinder 3 Starter motor 4 Reed valve pack 5 Pinion 6 Transmission cover 7 Water pump 8 Ignition cover 9 Gear sensor 10 Clu...

Page 21: ...SSEMBLY 2 2 ENGINE COMPONENTS LAYOUT EN SMR 1 Cylinder head 2 Cylinder 3 Starter motor 4 Reed valve pack 5 Water temperature sensor 6 Transmission cover 7 Injector 8 Water pump 9 Ignition cover 10 Gea...

Page 22: ...and the protection bracket 3 NOTE Upon reassembly make sure that the two bushes 4 are present on the pinion cover 2 Tighten the two screws 1 with a torque of 15 Nm 1 5 kgm 11 6 ft lb 2 4 Pinion Remova...

Page 23: ...the thread 3 with lithium grease and screw with a torque of 30 Nm 3 0 Kgm 22 12ft lb 2 6 HEAD removal Remove the spark plug and the temperature sensor as described in the relative paragraph Undo the s...

Page 24: ...lean 2 7 1 Disassembly Unscrew the two screws 1 Collect the two Teflon washers 2 for each screw Remove the injector 3 Remove the injector 3 from the duct 4 clean it and put it in a plastic bag so that...

Page 25: ...are positioned as shown in the figure Tighten so that the screw is packaged with the wash ers and then tighten another 1 4 turn NOTE If the Teflon washers 2 are damaged replace them 2 8 CYLINDER AND...

Page 26: ...22 3 4 6 6 7 5 ENGINE DISASSEMBLY Remove the cylinder 3 by sliding it from the stud bolts Remove the gasket 4 Remove the lock ring 5 of the piston 6 Extract the pin 7 and remove the piston 6...

Page 27: ...fore fitting the new rings on the piston it is necessary by means of a file to Break the corner by chamfering on both sides 1 and 2 the upper open part of the ring An N is printed on the upper part In...

Page 28: ...amaged Install the rings 2 and 3 positioning them with the face engraved with an N on the upper part Check that the rings rotate freely around the piston and are not obstructed Position the open part...

Page 29: ...ton so that the cylinder and piston coupling is 0 08 0 09 mm 0 0031 0 0035 in 2 8 7 Cylinder replacement When there is a need to replace the cylinder the piston must also be re placed so that the cyli...

Page 30: ...s been replaced it is necessary to check the squish as described in the paragraph Checking the squish 2 9 Checking the squish Cut a piece of tin as straight as possible of the length equal to the diam...

Page 31: ...from the piston and measure the thickness squish which must be between 1 6 1 7 mm 0 63 0 67 in NOTE Ifthemeasuredmeasurementisnotwithintheestablishedmeas urement the base gasket 7 of the cylinder mus...

Page 32: ...er in a vice and unscrew the screws 1 of the cover 2 Remove the cover 2 and check the gasket 3 if dam aged replace On the opposite side unscrew the nut 4 which locks the valve control lever 5 Remove t...

Page 33: ...ENGINE DISASSEMBLY Check the condition of the bearing 9 if damaged replace by removing the seeger 10 With an aluminum punch 11 and a hammer extract the pin 12 from the opposite side Remove the pin 12...

Page 34: ...GINE DISASSEMBLY Remove the socket 14 Remove the seal 15 and the roller bearing 16 located behind 2 10 1 Dismantling the lever 5 Withdraw the spring 17 from the pin 18 of the lever 5 Undo the screw 19...

Page 35: ...d Put loctite 243 on the thread 21 Recompose the lever and tighten the screw 19 Insert the spring 17 in the pin 18 and on the screw 19 2 10 3 Reassembly of the valve 13 Reassemble the roller bearing 1...

Page 36: ...f the cylinder Grease the pin 12 with graphite grease and reassemble it in the cylinder To insert the pin 12 completely use an aluminum punch and lightly tap on the head of the pin Refit the cover 2 b...

Page 37: ...n key 22 on the screw 6 and screw the nut 4 2 10 4 Valve height adjustment in closed position With the valve completely closed the distance between the upper surface of the cylinder 23 and the chamfer...

Page 38: ...ades Unscrew the screws 1 that fix the external frame 2 of the reed valve pack Check the rubber fitting 3 on the carburettor throttle body if damaged cracked etc replace Check the OR gasket 4 if damag...

Page 39: ...l frame 7 Remove the external blades 8 With a screwdriver slide out the two internal stops 9 Remove the internal blades 10 Check the state of the blades if chipped or deformed they must be re placed T...

Page 40: ...lubricate the gaskets with clutch oil Re mount everything proceeding in the opposite order to disassembly Tighten the screws 1 with a torque of 8 Nm 0 8 kgm 5 9 ft lb 2 13 Gear sensor Remove the flyw...

Page 41: ...2 Remove the gasket 3 Retrieve the two centring bushes 4 NOTE On re mounting check that the two centring bushes 4 are positioned correctly Clean the surface of the cover and the split crankcase of any...

Page 42: ...ten the two screws 3 of the stop plate 4 with a torque of 5 Nm 0 5 kgm 3 68 ft lb 2 14 3 Pick up Remove the rotor as described in the relative paragraph Unscrew the two screws 1 and remove the pick up...

Page 43: ...LY Remove the complete rotor 1 Retrieve the key 6 Re mounting Make sure the key 6 is properly positioned in its housing Re mount the fly wheel 1 Tighten the nut 2 with relative curve washer with a tor...

Page 44: ...e relevant paragraphs Remove the Bendix starter 1 Unscrew the two starter motor fastening screws 2 Remove the starter motor 3 2 15 2 Re mounting Check the status of the OR gasket 4 positioned on the s...

Page 45: ...6 1 ENGINE DISASSEMBLY Tighten the screws 2 with a torque of 10 Nm 1 0 kgm 7 38 ft lb Grease the bronze bush 5 with graphite grease Grease the gears 6 of the Bendix 1 and reassemble it in the bronze...

Page 46: ...minum washer 2 Remove the cap A from the generator cover B Check the condition of the gasket C if damaged replace Insert a T wrench 7 through the flywheel cover to block the rotation of the crankshaf...

Page 47: ...m 0 8 kgm 5 9 ft lb by replacing the aluminum washer 2 of the screw 1a Refit the cap 4 2 16 2 Water pump removal Undo the screws 1 the screw 1a is the system drain screw and is equipped with an alumin...

Page 48: ...t 7 from the crankcase 5 Check the condition of the seal 9 if damaged replace Check the correct functioning of the bearing 10 if it does not slide freely replace to replace heat the crankcase to a tem...

Page 49: ...sert the pump shaft 7 in the bearing 10 and in the seal 9 Place the shaft 7 in a vice and screw the impeller 8 with a torque of 6 Nm 0 6 kgm 4 42 ft lb greasing the thread Refit the transmission cover...

Page 50: ...4 4 ENGINE DISASSEMBLY 2 17 TRANSMISSION GUARD Unscrew the screws 1 1a M5 L25 screw 1b M5 L30 screw 1c M5 L70 screw Remove the guard 2 with the aid of a rubber hammer Remove the gasket 3 Recover the t...

Page 51: ...bushes 4 are in their respective housing Replace and re mount the gasket 3 Mount the cover 2 centring it on the bushes 4 paying attention not to ruin the seals Tighten the screws 1 crosswise positioni...

Page 52: ...r dismantling In sequence remove the washer 4 spring 3 socket and ratchets 5 the seeger 6 shim 7 gear 8 shaft 9 socket 10 and the spring 1 Re assembleinreverseordertodismantling payingattentiontoposit...

Page 53: ...the transmission cover as described in the relative paragraph Remove the clutch discs as described in the relative paragraph Open the lock washer 1 with a chisel Use a spanner to block rotation of th...

Page 54: ...e the two roller bearing 6 and the spacer 7 Remove the washer 8 2 19 2 Re mounting Insert the washer 8 Re mount everything proceeding in the reverse order to disassembly Make sure that the spacer 7 an...

Page 55: ...having re mounted the bell 5 and the drum 2 make sure the safety washer 1 has been positioned correctly Screw the nut 3 blocking drum rotation with a spanner with torque of 100 Nm 10 0 kgm 73 75 ft lb...

Page 56: ...2 Idle gear kick starter removal 3 Kick starter 4 Gearbox primary shaft 5 Gearbox command shaft 6 Crankshaft gear 2 20 1 Gears removal Remove the pedal start gear 3 as described in the relevant paragr...

Page 57: ...1 Collect the key 10 Remove the seeger 11 of the crankshaft gear 6 Remove the crankshaft gear 6 2 20 2 Reassembly of gears Reassemble the gear 6 of the crankshaft by matching the arrow 12 stamped on...

Page 58: ...243 on the oven 16 and not on the screw Tighten the screw 9 with a torque of 22 Nm 2 2 kgm 16 22 ft lb loctite 243 Put graphite grease on the bronze bush 17 and reassemble the gear 2 Refit the washer...

Page 59: ...he 5th or 6th gear according to the type of en gine Remove the transmission casing and the countershaft gear as described in the relevant paragraph Remove the gearbox control shaft 1 and recover the s...

Page 60: ...mantle the ratchets 7 and 8 with the relative tips 9 and the springs 10 Unscrew the pin 11 securing the desmodromic shaft head 12 Remove the pin 11 With a screwdriver 13 move the rod 14 and with a scr...

Page 61: ...le the rod 14 by correctly positioning the spring 17 and tight ening the screw 16 with a torque of 10 Nm 1 kgm 7 37 ft lb Use a screwdriver 13 to move the rod 14 and fit the gear selection ring 12 by...

Page 62: ...y into their seats the two ratchets cannot be reversed Fit the ratchet support 6 on the plate 5 Fit the plate 5 on the pin 11 by inserting the ratchet support 6 in the ring nut 12 tighten the screws 4...

Page 63: ...ission side as described in the relative paragraphs 2 22 1 Opening On the transmission side remove the gearbox secondary shaft locking see ger 1 Unscrew the screws 2 M6 x 50 and the screw 3 M6 x 35 Tu...

Page 64: ...rectly positioned in their housing and that the centring bushes 8 and 9 are mounted Clean first with an iron spatula and then with scotch brite the contact surface from any residual sealant paste and...

Page 65: ...ve housing depending on their length and tighten them with torque of 12 Nm 1 2 kgm 8 68 ft lb 5a M6 x 50 5b M6 x 35 5c M6 x 60 Refit the countershaft 4 Tighten the screws 2 M6 x 50 and the screw 3 M6...

Page 66: ...earbox primary shaft 3 Gearbox secondary shaft 4 Gears selector drum desmo 2 23 2 Crankshaft removal Using a rubber hammer slide the complete crankshaft 1 from the semicase If necessary heat the beari...

Page 67: ...Y Spread the forks and remove the gear selector drum 4 desmo Remove the fork 5 of the primary shaft Remove the complete gear assy 6 with the fork inserted 2 23 4 Primary shaft gear sequence 2a Primary...

Page 68: ...the bearing and remove the plates 2 Unscrew the screw 3 with relative bearing safety washer Remove all seals Heat the guards and remove the bearings 4 NOTE Afterhavingreplacedthebearings re positiont...

Page 69: ...he condition of the OR gasket 9 if damaged replace NOTE Check that the pin 8 of the fork 2 is not worn if worn replace Check that the fork rollers are correctly inserted in the relative hollows on the...

Page 70: ...disassembly lubricating with engine oil and when re mounting the gearbox unit paying attention to correctly position the forks 2 5 and 7 in the relevant positions Fork 2 cod 33024 between the 5th and...

Page 71: ......

Page 72: ...www tmracing it...

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