2003 KX 125 Clutch Problems

Here is a customers bike that has some clutch problems.  It started out as just some noise, but then developed into some more serious problems and even some breakage.  Upon inspection of the clutch basket, hub, and pressure plate, it was obvious that they all needed replacing.  If you have ever priced these clutch components, you know how expensive they can be.  Before bringing the bike to me, the customer had taken it to a local shop and received an estimate of approximately $1200.  I was able to replace all of the clutch assembly, and even upgrade the clutch basket to a forged wiseco basket for less than half of that estimate!

Look at the pics below and notice in the 3rd and 4th picture you can see the notches in the original basket.  When they wear this much, clutch engagement becomes rough and choppy.

The 5th and 6th pictures show the wear to the inner clutch hub.  This part also develops notches from the steel plates in the clutch stack.  There is also a very noticeable trough cut into the edge of the hub.  Compare it to the new hub in pic 7.

Images 8,9, and 10 show the wear on the old pressure plate compared to the new one.  Again, notice the trough cut into the outer edge.

In order to install any new aftermarket clutch basket such as hinson, barnett, wiseco, etc., you must remove the original primary gear and kick start gear and install them onto the new basket.  This can be slightly time consuming.  The original rivets must be drilled and removed, then the backing plate can be gently pried off.  The rubber cushions have to be re-used also, so pay attention to their orientation, it is easy to reverse them.  The kick start gear must be pressed off.  This can be done in a vice with a socket and a section of pipe.  To install this gear on the new basket, the simplest way is to put the gear in the freezer and the basket in the oven both for about 15-20 mins.  If you can do it fast enough, it will almost drop in.
Once you have the gears installed, and the backing plate screws are torqued to the proper specs with loc-tite, you can start putting it all back together.  New clutch friction plates must be soaked in oil prior to installation.  Refer to your manual for re-assembly if you forget where any parts go.

With the new clutch installed, it now engages smooth and there is no more noise.  The lever pull feels like a hydraulic clutch instead of a cable-operated one.

Author: joedean

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