Vintage Dirt Bike Q & A

OK, I have now been chasing a shift problem for the last 6 weeks on my '79 CR125. My issue is that under load (running engine) I can't upshift into second. I can feel the gears not meshing at all (not really grinding, just not meshing).

But, on the stand turning the rear wheel by hand, I can run thru all the gears w/o a problem. The alignment marks are spot on perfect. I have had the cover off no less than 8 times now.

Gears, forks & drum were all in very good condition and within OEM specs, All the linkage has been replaced as have all the springs (NOS). Still the same problem.

Only part I have not replaced is the clutch linkage lifter arm. I can operate the clutch fine, but it does show some wear. The rod and lifter as NOS replacements.

Last week I was able to double clutch & double shift and got second. From there all the other gears work fine (2, 3-6). Shifts into first & neutral everytime w/o an issue. Just hanging up into second.

Any ideas I have not attempted?????????????

So I guess it wasn't reversed shift forks after all? Have you replaced the shifter shaft? If your shift lever was bent, I'd suspect everything it was connected to, with the shift shaft #1 on the list. I've already told you about my MR; from 1st it would barely get into neutral on the bench, forget about 2nd and above. And obviously both shift pawls are in correctly? They're easy to put in flipped over.

Ray

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'74 CR125M (175cc), '75 MR175, '82 RM250Z, '08 YZ250F, '14 Zero FX electric, '14 Zero MX electric, '18 Alta MXR electric

Ray,

Everything thing is correct. Shift lever has a slight twist at the end, but when I did get 2nd, shifts fine in the other gears. I did swap over to a different shift shaft, pawls are in correctly and it shifts fine w/o the engine running. As soon as normal engine load is applied, second hangs up. I can feel the gears not meshing.

I may try the clutch arm as I have a better one to replace it with. Wonder if the cases have wear that allows the internals to move enough to cause this bind?

Any chance the countershaft 2nd gear slots, CS 6th dogs, or CS splines are worn/damaged? Or the washer between them got swapped for the wrong one? If everything's assembled correctly, we're pretty much grasping at straws. I usually remember to check the gear teeth, but almost always forget to check the slots & dogs.

Ray

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'74 CR125M (175cc), '75 MR175, '82 RM250Z, '08 YZ250F, '14 Zero FX electric, '14 Zero MX electric, '18 Alta MXR electric

My mechanic had it apart and did the inspection on the lower end. The previous owner (knucklehead) had the shift forks in wrong. I may end up getting another transmission and a puller to get the flywheel off. Have a nice shift drum and the forks are said to be in nice condition...........just puts me another $100 into the bike.

Well, been riding the bike some, and can get into 2nd by double shifting. Upper range is no problem, downshifting is fine. Racing at Hixton, WI on the 28th. Will try to stay in the upper range as much as possible.