Diagnosing Transmission Problems

Some problems that come up and where you might find the solution....

Difficulty Shifting.
When you need excessive clutch lever pressure to shift gears, it may indicate either a clutch problem or a transmission problem. If the clutch is at fault , you will notice symptoms such as grinding gears when you shift into low or first gear. In most cases if the clutch is at fault, a simple adjustment will solve the problem. If the transmission is at fault you will notice difficult shifting between other gears while the motorcycle is moving. this problem may indicate a bent shift fork or possibly a seized gear on the transmission shaft. When a shift fork is damaged, it no longer fits properly in the grooves of the gear.
To fix this problem, you'll need to disassemble the unit and replace the shift fork. When a gear has seized on the transmission shaft the problem is usually caused by a lack of proper lubrication. As with the shift fork, you will also need to disassemble the engine to repair the problem on sporties.

Inability to shift gears.
Occasionally you'll find a machine that shifts into one gear, but won't shift into the next gear. This problem is often caused by the shift return spring which returns the shifting lever to its original position. You can usually repair this problem by replacing the spring. The spring is usually located near the clutch assembly. In most cases, you wont need to completely disassemble the engine to repair the problem

Strange Sound.
Unusual sounds may range from a low growl to a high pitched whine below I'll describe the most common noises which indicate a transmission problem. Any unusual noise coming from the transmission will require you to disassemble and carefully inspect for worn or broken parts

Constant Growling sound
A low growling sound usually indicates a bearing failure. when a bearing fails, it may cause a transmission shaft to move slightly out of position. When this occurs, the gears do not mesh properly and produce a low growling noise. In these case not only do you need to replace the bearing, but you will most likely need to replace the gears as well.

Clunking Noise
An excessive clunking sound when the engine is in a particular gear while under load usually indicates broken teeth on one or more gears. In this case, you'll need to replace the gears, the shift fork, and the shift drum as needed.

Jumping Out of Gear.
When dogs and slots become to rounded, the gears will tend to slip out of the holes when the engine rpm increases, and the transmission jumps out of gear. The shift forks may also become damaged from the excessive pressure they encounter as the transmission jumps out of gear. Therefore, when a transmission is jumping out of gear, you'll need to replace the gears, the shift forks, and the shift drum as needed after an inspection of these parts..