Dismanteling the new 250/300Fi 2S TM Racing engine

The TM Racing 250 / 300Fi 2S engine is new in 2020. To help you maintain your tm racing motorcycle. We wanted you to do a tutorial presenting the complete disassembly from A to Z, or should we say from cylinder head to the gearbox.

The different stages concerning the reassembly of the engine are indicated in bold.

This tutorial is for the following bikes :

TM Racing 250Fi 2S EN/SMR 2020

TM Racing 300Fi 2S EN/SMR 2020

TM Racing 250 2S EN/SMR 2019 (almost all the tutorial)

TM Racing 300 2S EN/SMR 2019 (almost all the tutorial)

TM Racing 250 2S MX 2019/2020 (almost all the tutorial)

TM Racing 300 2S MX 2019/2020 (almost all the tutorial)

Removing the pinion cover from the TM Racing

1 - Unscrew the two screws (1).

2 - Remove the pinion cover (2) and the protection bracket (3).

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

3 - Remove the seeger ring (1).

4 - Remove the pinion (2).

Temperature sensor removal of the TM Racing 250Fi 2S engine

1 - Unscrew the sensor (1) and remove it from the head. Check that the OR gasket (2) is not damaged.

When refitting, smear the thread (3) with lithium grease and screw with a torque of 30 Nm

2 - Remove the spark plug and the temperature sensor as described in the relative paragraph.

Undo the screws (1).

3 - Remove the head (2).

Upon reassembly, replace the seals (3) and screw the screws (1) without tightening, then tighten them crosswise with a torque of 20 Nm

Injectors disassembly of the TM Racing 300Fi engine 2020

Before disassembling the injector, the area around the injector must be clean.

1 - Unscrew the two screws (1). Collect the two Teflon washers (2) for each screw.

2 - Remove the injector (3).

3 - Remove the injector (3) from the duct (4), clean it and put it in a plastic bag so that it does not get dirty. If the duct (4) with its piping must also be dismantled, also put these in a plastic bag so that they do not become dirty.

Cylinder and piston of the 250 2 stroke injected

The drain valve nut (1) must be screwed or unscrewed only when the valve has to be overhauled and only with the cylinder removed.,Do not act on the nut (1) with the cylinder mounted as there may be adjustment problems.

1 - Unscrew the nuts (2) as follows: L oosen the nuts (2) then completely unscrew the nuts (2).

2 - Remove the cylinder (3) by sliding it from the stud bolts.

3 - Remove the gasket (4).

4 - Remove the lock ring (5) of the piston (6)

5 - Extract the pin (7) and remove the piston (6).

6 - Remove the roller cage (8).

Reed valve pack from the TM Racing 300Fi 2020

1 - Unscrew the screws (1) that fix the external frame (2) of the reed valve pack.

2 - Check the rubber fitting (3) on the carburettor/throttle body, if damaged, cracked, etc. replace.

3 - Check the OR gasket (4); if damaged, replace.

4 - Remove the reed valve pack (5) and the relative gasket (6); if damaged, replace.

5 - Remove the internal frame (7).

6 - Remove the external blades (8).

7 - With a screwdriver, slide out the two internal stops (9).

8 - Remove the internal blades (10). Check the state of the blades, if chipped or deformed, they must be replaced.

Dismantel clutch and clutch actuator of the TM Racing 250Fi 2020

1 - Unscrew the screw (1) and remove the actuator (2).

2 - Remove the piston (3). Check the conditions of the OR gaskets (4 and 5); replace them if ruined. On re-mounting, lubricate the gaskets with clutch oil.

3 - Unscrew the M5-L25 screws (1).

4 - Remove the flywheel cover (2).

5 - Remove the gasket (3). Use a new one on the re-assembling process

6 - Retrieve the two centring bushes (4). 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 residues and check that the gasket (3) is not damaged, otherwise replace. Tighten the screws (1) with a torque of 8 Nm

7 - Unscrew the two grub screws (1). Remove the sensor (2). Reassemble everything in the reverse order of disassembly, taking care to position the non-threaded part of the grub screws (1) in the brass bushes (4).

8 - Position the cable harness (5) as originally and reassemble the flywheel housing.

9 - Remove the flywheel cover as described in the relative section. Unscrew the screws (1) that secure the stator (2). Unscrew the screws (3) and remove the stop plate (4). Remove the stator (2) with the relative cabling.

10 - Unscrew the two screws (1) and remove the pick-up (2).On re-mounting, check that the washers notched under the screws (1) are positioned correctly. Tighten the two screws (1) with a torque of 8 Nm (0.8 kgm, 5.9 ft/lb) + Loctite 243. Make sure the rubber cap (3) is fitted correctly on the guard.

11 - Block rotor rotation (1) and use an impact gun to loosen the nut (2) with relative curve washer (3).

12 - Screw the extractor (4) onto the thread of the rotor (1) and tighten the screw (5) to detach the rotor (1) from the crankshaft.

13 - Remove the complete rotor (1).

14 - Retrieve the key (6). Make sure the key (6) is properly positioned in its housing.

Starter motor of the 300 2 stroke TM Racing engine

1 - Remove the Bendix starter (1).

2 - Unscrew the two starter motor fastening screws (2).

3 - Remove the starter motor (3).

Water pump of the 250 2 stroke TM Racing engine

1 - Undo the screws (1); the screw (1a) is the system drain screw and is equipped with an aluminum washer (2). Remove the pump cover (3).

2 - Check the condition of the gasket (4) if damaged, replace. Remove the transmission cover (5) as described in the relative paragraph.

3 - Put aluminum jaws (6) in a vice and lock the shaft (7) of the water pump.

4 - Unscrew the impeller (8).

5 - Remove the shaft (7) from the crankcase (5).

6 - 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 temperature of 50° C and with a punch remove the bearing and reassemble the new one.

Transmission guard of the TM Racing

1 - Unscrew the screws (1)

2 - Remove the guard (2), with the aid of a rubber hammer.

3 - Remove the gasket (3).

4 - Recover the three centring bushes (4).

Idle Kick starter removal

1 - Release the spring (1) from the relative housing, turn the starter (2) anticlockwise by 1/4 of a turn.

2 - Remove the starter (2) complete with spring (3) and washer (4).

3 - 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).

Drum and clutch bell of the TM racing 300Fi 2S engine

1 - Open the lock washer (1) with a chisel.

2 - Use a spanner to block rotation of the clutch drum (2) and tighten the nut (3).

3 - Remove the safety washer (1).

4 - Remove the drum (2).

5 - Remove the washer (4).

6 - Remove the bell (5).

7 - Remove the two roller bearing (6) and the spacer (7). Remove the washer (8).

Transmission side counter gears

Components layout: :

1. Countershaft gear
2. Idle gear kick starter removal
3. Kick starter
4. Gearbox primary shaft
5. Gearbox command shaft
6. Crankshaft gear

1 - Remove the pedal start gear (3) as described in the relevant paragraph.

2 - Unscrew the fixing screw (7) of the pedal start retaining gear (2) .

3 - Remove the screw (7) and the washer (8). Remove the gear (2).

4 - Unscrew the screw (9) of the countershaft (1). Remove the gear (1).

5 - Collect the key (10).

6 - Retirer le clip (11) du pignon (6) de l'arbre de vilebrequin et retirer le.

Gearbox control shaft and ratchets holder removal

1 - Turn the gearbox putting the 5th or 6th gear according to the type of engine. Remove the transmission casing and the countershaft gear as described in the relevant paragraph. Remove the gearbox control shaft (1) and recover the shim (2).

2 - Remove the socket (3).

3 - Unscrew the two screws (4).

4 - Remove the pawl ratchet plate (5). Remove the ratchet support (6) from the plate (5).

5 - Dismantle the ratchets (7) and (8) with the relative tips (9) and the springs (10).

6 -Unscrew the pin (11) securing the desmodromic shaft head (12). Remove the pin (11).

7 - With a screwdriver (13) move the rod (14) and with a screwdriver (15) lever to remove the ring nut (12).

8 - Remove the ring nut (12).

9 - To remove the rod (14) unscrew the screw (16).

Semicase separation of the TM Racing 250Fi 2S 2020

1 - On the transmission side, remove the gearbox secondary shaft locking seeger (1). Unscrew the screws (2) M6 x 50 and the screw (3) M6 x 35.

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

3 - Undo the screws (5). Take not to forget any.

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

Crankshaft, gearbox, gear drum of the TM racing 300Fi 2S engine

Components position :

1. Crankshaft
2. Gearbox primary shaft
3. Gearbox secondary shaft
4. Gears selector drum (desmo)

2 -Using a rubber hammer, slide the complete crankshaft (1) from the semicase. If necessary, heat the bearing to facilitate removal of the crankshaft.

3 - Extract the secondary shaft fork pin (1) complete with fork (2).

4 - Slide the primary shaft fork pin (3) out.

5 - Spread the forks and remove the gear selector drum (4) (desmo).

6 - Remove the fork (5) of the primary shaft.

3 - Remove the complete gear assy (6) with the fork inserted.

Primary shaft, gear sequence

Secondary shaft, gear sequence

Bearing replacement 250/300Fi 2S 2020

1 - Unscrew the screws (1) that block the bearing and remove the plates (2). Unscrew the screw (3) with relative bearing safety washer. After having replaced the bearings, re-position the safety washers and tighten the screws again and applying Loxeal 82-33 on the thread.

2 - After having the case warmed at around 50°C extract the bearing.

Your 2020 TM Racing 250 or 300Fi engine is now completely disassembled. Only reassemble your engine with original parts guaranteeing its reliability. All original parts are available, in case of doubt, do not hesitate to contact us.

TM Racing 250/300Fi 2S dismanteling process