How-To: KX250F Shifting Problem – Broken Case Detent
Year, Make, Model
2006 Kawasaki KX250F
Symptoms
The gear shift lever will not return to original position once lever has been pushed up or down. If 1st or 2nd gear is selected, it will stay in the down or up position and not return to it’s “neutral” state.
Diagnosis
I had a feeling that the problem had to do with the detent system that is located under the RH side engine cover. After removing the cover, is was very apparent what failed. There is a pin that is pressed into a boss in the case that broke off and did not allow the gear shift lever to spring back into its neutral position.
How did this happen?
The owner told me that his very worn chain (and sprockets) fell off the front sprocket and became wrapped up and eventually slammed the gear shift lever down pretty hard.
I guess this failure can also be caused by accidentally using the gearshift lever as a footpeg when landing from a jump.
Tools
Parts List & Cost
You have 3 options on repairing the cracked case:
1. Have it TIG welded. This is the cheapest option and what we originally decided to do. I know a good TIG welder that can attempt welding this aluminum case. The weld turned out OK, except quite a bit of the weld bead would have to be ground down for clearance on all the parts that need to be stuffed back into the case. We ended going with option 3.
2. Buy a used set of cases. Yes, I said set, meaning both left and right matched sides. This is also how they sell new, as a matched set. The cases are most likely machined in the same CNC setup for accuracy purposes. You can probably get away with buying a RH case on ebay or the classified section of forums, but there is a chance they may not line up properly and cause binding in the crank and gearbox. The owner lost a few auction and others were going for more than new, so we went with option 3.
3. Buy new cases. Pricey, however the best option. The downside is transferring all the bearings and other parts.
How-To Video
The video above will show you how to open the RH cover and look for the failure. I cover the repair in a later video called “How-To: KX250F Top & Bottom End Engine Rebuild“, where the cases will have to be split and either welded, or replaced with new or used RH case.
Comments
Did your shifter fail also? Did this video and post help you out? Comment below.
I have a problem with my 08 kx250f. In first gear and only in first gear there is a clunking/rattling sound coming from the chain or gearbox, i’m pretty sure it is not the chain because the noise is pretty loud or noticeable. In first gear is is also very jerky. Again the bike runs great in neutral and in every other gear. please help!
Sounds like you need to start taking it apart, possibly split the cases. Check out my engine rebuild video: https://howtomotorcyclerepair.com/kx250ftopbottomrebuild/
Same problem with my 07 KX 250T7F. Only case set I can find is new and it’s at least $600. My idea is to drill and tap the pin and use a bolt from the other side of the case to tighten it down. Going to put high temp jb weld on the mating surfaces and high temp locktite on the threads. Before I put it together, i’m going to look into modifying the pin and/or the shift rod to prevent it from happening again.
I got to this website by searching for a different problem with the same engine. The bearing came off the position lever. It’s only $14 for the part but very much hassle.
Also during tear down I noticed gouging *weird* on the pencil diameter push rod that pushes against the marble that opens the clutch. I need to show all this to a dirt bike mechanic to see what he thinks is going on.