Modify A Motorcycle Clutch For A Race Application

Racing clutches are designed to withstand the many gear changes during a race.

Modifying a clutch for race application is necessary for improved performance. A typical race on a paved road course or a motocross course may have as many as 70 or 80 rapid gear changes each lap, and factory clutches are not up to this type of abuse. Racing clutches use stronger clutch springs that engage the clutch plates with greater force. In addition, the lifter spring that pushes the operating rod against the pressure plate must be upgraded, as well. Modifying a motorcycle clutch for race applications includes removing the factory components and installing the components provided in a racing clutch kit.


Take Down

1. Park the motorcycle on the kickstand and place an oil pan under the engine. Remove the oil drain plug with a metric socket and ratchet, turning the plug counterclockwise. Drain the engine oil. Set the drain plug aside and allow the residual oil in the crankcase to drain into the pan.

2. Loosen and remove the clutch bolts with a socket and ratchet, turning the cover bolts counterclockwise. With some bikes, it may be necessary to remove the rear brake pedal in order to access the bolts on the lower edge of the cover. Refer to the owner’s manual and remove the brake pedal, if necessary. Remove and save the clutch cover bolts. Pull the clutch cover off the clutch housing to access the clutch pressure plate. Set the cover aside.

3. Remove the clutch pressure plate bolts counterclockwise in a crisscross pattern using a socket and ratchet. The bolts are pre-loaded by the clutch springs behind the plate; fully removing the bolts one at a time is not advisable. Remove the pressure plate bolts and set them aside. Pull the circular lifter off the end of the operating rod in the center of the clutch components. Set the lifter aside.

4. Pull the factory pressure plate off and discard it. Pull the factory clutch springs off the spring posts inside the clutch housing by hand and discard them. Pull the lifter rod out of the center of the clutch housing by hand and set it aside.

5. Pull the individual factory clutch plates and metal discs out of the clutch housing by hand. Discard them. Remove the lifter rod spring from the circular metal cup at the back of the clutch housing by hand and discard it.


6. Clean the clutch housing thoroughly using a rag with a modest amount of transmission oil. Turn the rag frequently to pick up and remove all clutch plate debris and dirt. Inspect the housing and make sure it is free of debris or dirt. Clean it again, if necessary.

7. Push the new lifter spring into the circular metal cup in the center of the clutch housing. Coat the saved lifter rod with lithium grease. Push the lifter rod into the center of the lifter spring and fully into the circular metal cup.

8. Coat each side of the new clutch plates with transmission oil. Install a new metal clutch disc against the back of the clutch housing by hand. Install a new clutch plate against the metal disc by hand. Install the remaining clutch discs and clutch plates alternately by hand until all are in place in the clutch housing.

9. Push the individual racing clutch springs onto the spring posts at the back of the clutch housing. Put the saved lifter on the end of the lifting rod. Position the new racing pressure plate against the clutch springs and align the boltholes in the new plate with the openings in each clutch spring.

Insert the saved clutch plate bolts into the pressure plate holes and thread them clockwise by hand. Tighten the bolts in a crisscross pattern using a torque wrench. Typical torque is approximately 7 ft. lbs. for each bolt.

10. Align the bolt holes in the saved clutch cover with the holes on the face of the clutch housing. Thread the saved cover bolts clockwise into the holes by hand. Tighten the clutch cover bolts clockwise with the socket and ratchet.

Reattach the rear brake pedal, if you removed it. Thread the saved drain plug clockwise into the bottom of the crankcase and tighten it clockwise with the socket and ratchet. Fill the engine crankcase with fresh oil.