Suzuki's RM125 dirt bikes rely on a series of 15 steel and fiber clutch plates to generate friction against the clutch basket, allowing the transmission to be engaged and disengaged from the engine at will. The clutch plates will begin to wear with time, allowing the clutch plates to slowly lose their grip. This results in clutch slip, often felt as a momentary lack of power as the engine races to a higher rpm. This can result in unpredictable power delivery that can cause a loss of control. Although the task may appear difficult, most RM125 owners can replace the clutch plates on their own with only a few tools.
Things You'll Need
- Side stand
- 10 and 17 mm sockets
- Socket wrench
- Oil catch pan
- Torque wrench
- 5 mm Allen wrench
- Eight fiber friction clutch plates
- Seven steel clutch plates
- SAE 10W-40 motorcycle-grade engine oil
- Six clutch springs
- Cotter pin
Place the motorcycle on a side stand, then start the engine. Let the engine warm for three minutes, then stop the engine and let it cool for another three minutes.
Remove the oil filler cap from the top of the clutch cover, located on the right side of the engine. Unscrew the transmission-oil drain bolt from the bottom of the engine crankcase, using a 17 mm socket and a socket wrench. Lift the motorcycle into an upright position and drain the transmission oil into an oil catch-pan. Screw the drain bolt into place by hand once the oil has drained completely. Tighten the bolt to 14.5 foot-pounds, using a torque wrench.
Remove the cotter pin from the rear brake pedal pivot, using pliers. Push the pivot out from the rear of the brake pedal. Remove the brake pedal, using a 5 mm Allen wrench.
Remove the clutch cover and gasket, using a 10 mm socket.
Unscrew all six clutch spring bolts from the outer face of the clutch pressure plate, using a 10 mm socket. Pull the spring bolts and the clutch springs out of the pressure plate spring wells, then pull the pressure plate off the clutch basket. Remove the clutch push rod and bearing from the center of the clutch basket.
Grasp the clutch plate stack and pull it out of the clutch basket. There will be 15 clutch plates altogether; eight fiber friction plates and seven steel clutch plates.
Soak the new clutch plates in SAE 10W-40 motorcycle-grade engine oil for 10 minutes. Slide the new clutch plates into the basket, starting with a fiber friction plate, followed by a steel clutch plate. Continue until the last friction plate has been placed into the clutch basket.
Reinstall the clutch push rod and bearing, with the bearing rollers facing the engine, into the clutch basket, then push the pressure plate into place. Align the pressure plate spring wells with the clutch basket's mounting holes. Push a new set of clutch springs into the spring wells, then hand-thread the spring bolts into place. Tighten the spring bolts to 3.3 foot-pounds, alternating between bolts diagonally to evenly tighten the pressure plate against the clutch plates.
Reinstall the clutch cover and gasket. Tighten the clutch cover bolts to 8 foot-pounds.
Reinstall the brake pedal on its mounting shaft. Tighten the brake pedal bolt to 18 foot-pounds. Push the rear brake pivot into the rear of the brake pedal. Insert a new cotter pin through the brake pedal pivot and bend its legs around the pivot, using pliers.
Fill the engine crankcase with 0.5-quart of SAE 10W-40 motorcycle-grade engine oil, then screw the oil filler cap into place. Start the engine and let it warm for three minutes, then stop the engine and let it cool for another three minutes.
Lift the motorcycle into an upright position and hold it in place. Loosen the oil level check bolt, located at the 4 o'clock position on the clutch cover. Oil should begin to seep out of the engine as soon as the bolt is loosened sufficiently. If oil does not begin to leak from the oil-check bolt-hole, add oil into the crankcase until a leak appears. Tighten the bolt to 8 foot-pounds
Pull in the clutch lever until you feel resistance and hold it in place. Measure the distance between the clutch lever and the lever perch, using a vernier caliper. Ideally, there should be a 1/8-inch gap between the lever and the perch. Adjust the gap, using the cable adjuster on the rear of the perch, if the gap is greater or less than 1/8-inch.
Tips & Warnings
- Used engine oil often contains harmful metal fragments and toxins. Store used oil in a sealable container, out of the reach of children or animals, until it can be disposed of properly Do not dump the oil down a drain or into a trashcan; instead, take the oil to a Suzuki repair center or auto parts supplier for recycling.
- Suzuki RM125 Owner's Service Manual; Suzuki Motor Corporation