2008 rmz250 4th gear conundrum

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4/23/2018 11:56 AM

Here’s the problem: My 2008 rmz250 hits what seems to be false neutral when shifting from 3rd to 4th gear. I did split the cases and inspect the gears/forks/dogs and couldn’t seem to find anything that stuck out as to why this bike won’t shift correctly. Also, to back that up, when the bike is not running it will shift through all of the gears fine, locking the shaft so that I know it is going into gear. I was thinking maybe the star cam is worn or the detent spring is just weak and isn’t holding it in gear. Does anyone have any idea what might be causing this?


4/23/2018 1:22 PM

My old kx125 had a worn drum. Visually you couldnt tell, but replacing it fixed it. Took pretty much an entire transmission swap to figure that one out lol.


4/23/2018 1:47 PM

Are you talking about the cam that the forks click into or the stopper cam that is on the clutch side of the case? I’m really trying to avoid splitting the cases...again


4/23/2018 2:20 PM

Its a cylinder shaped part with a bunch of slots in it.


4/23/2018 2:28 PM

That sounds like the shift cam where the forks lock in. I’ll be inspecting everything again, so this should be fun.



4/23/2018 2:31 PM

Check out the stuff on the clutch side first. That could very well be an issue too.


4/23/2018 2:46 PM

That’s the plan, the weird part that I can’t seem to get over is that it does lock into gear but only while it’s not running, it’s just while the engine is on it doesn’t. My guess is it’s going to be that cam on the transmission side or the other cam on the clutch side. It’ll probably end up being a $2 spring.


4/23/2018 2:55 PM

Sounds like you got it. Start cheap.


4/23/2018 4:44 PM

Typically if there is a major issue like that you will notice it shifting through on the stand or on the bench.

That spring has to apply just the right amount of pressure for all that to work harmoniously. Start on that side of the engine and rule out everything you possibly can before thinking about splitting the cases again.

I have also seen little burs and nicks on the shifting mechanisms that can cause hang-ups on less used portions of the drum (1-3 gears are your high-use gears that wear consistently).


4/23/2018 6:02 PM

Well I just took apart the clutch side and examined the detent spring, pawl springs, and the stopper cam and didn't find anything. I'm wondering if there is a stiffer detent spring that I can get-onr that is stiffer than OEM?

I did order a both a shift drum and stopper cam (found a sweet deal on eBay from a team's old part bike, barely used and in new condition) so I'll at least be able to replace the stopper cam, and see if the problem still happens, and then I'll have the drum for if I end up splitting the cases.