Yesterday I was riding at a local trial event and bike was running fine. And then I was unable to shift in second or neutral, it was stuck in 1rst gear. I didn't drop the bike or crash it on that day.

This morning I removed the transmission and I can't see what's wrong. I tried to change the shifter spring adjustment position with no luck. Unlike yesterday, now with the trans out, I can move between 1rst gear and neutral. But can't go up in 2nd gear.

Any idea of what can be the problem? I seached on the internet but didn't found anything similar.

 

When I try to shift, something is blocking the drum but I can't see what it is.

Maybe the shift drum is too worn and the mechanism doesn't work properly?

 

Does the wheel on the end of the index lever rotate?
As you obviously have a bit of wear on the drum.

Yes the wheel can rotate. But with nothing to compare, I can't tell if there's some worn on that wheel. Just to do some test, I installed the drum at the 4th or 5th gear where it is less worned on the drum and I can changed gear at this place. It is not smooth, but it work.

Edited August 2, 20224 yr by stou

Looks like the case hardening has broken down - therefore worn and makes changing gear difficult - replace selector drum ?

1 hour ago, happycyd said:

Looks like the case hardening has broken down - therefore worn and makes changing gear difficult - replace selector drum ?

That's what I think  too. Yesterday I looked all over to tried to find that part. Can't find it.

on the lower photo you can see a fragment of metal at 4 O'clock, It only needs something of this size in somewhere like a bearing to jam it solid. Perhaps there are more fragemts in the shift drum bearings. rinse it out with two stroke mix over a clean container and look for more fragments falling out. try to rotate drum bearings whilst rinsing.

I already checked both bearing and they rotate very well. What you see is only a reflexion of the light. There's no metal fragments.

I found the part in Europe, just wait for it now!

Hello stou

Might be unrelated, but I was warned not to tighten a bolt in the crank case of my Jotagas JT300 too tight because it then extends too far and interferes with the selector. There is a tech page that even says don't use this particular bolt to drain the oil.

Had you dumped the oil and refilled lately, then replaced the filler plug a bit tight or missing a washer, eg?

 

 

I just saw this. Did you get the gearbox solved?  Lewisport is still rebuilding them last I knew a couple months ago.

Talk to Adrian.

I think I have a new shift drum