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Transmission/shifting problems.

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Hey guys, I'm hoping you can help me out

I have a 2000 yz250 I purchased about 5 months ago. The previous owner completely rebuilt the bottom/top end. He was planning to race the bike and works at a rebuilt-able shop.

When I was at the track today I was have a hard time down shifting. Up shifting was fine, I did not have any problems there. But down shifting was off. It would take around 5-10 shifts to get from 4th/3rd to a lower gear. I could not use my toe to down shift, it would take the center of my boot.

When i got home I drained my transmission fluid and measured it. It was spot on- 750ml.

While the oil was draining I spun my rear tire and shifted the bike. It still had a tough time down shifting, but nothing like what it was experiencing at the track. When it did shift, it took a very long throw down on the lever. It was sweeping down over 30 degrees. My previous bikes would shift with the flick of a toe. This bike seems to need much more input to shift.

I then removed the clutch and basket to look at the shifting mechanism. Everything seems to looks fine to my untrained eye. Although the shift shaft has some axial play in it. I can grab my shifter and pull it out about 80 thousandths of an inch. But my prior experience suggests that is normal.

With the clutch removed, I repeated the above experiment. And I had the same results. Shifting was hit or miss and required much more input than normal.

I installed a steahly fww last night, but that shouldn't effect shifting. And the shift lever is not contacting anything when it is rotated.

Hopefully this is enough to figure this one out. I'm stumped. I can't figure why the bike up shifts fine, but struggles to down shift. Shift forks, drum, etc would cause problems on both shifts.? :thumbsup:

Thanks for any help, George.

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Although the shift shaft has some axial play in it. I can grab my shifter and pull it out about 80 thousandths of an inch. But my prior experience suggests that is normal.

Yep, that would be normal. Sounds to me like a bent shift fork. Another possibility is the cases being worn where the shift fork shafts slide although my bet is a bent fork.

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It would seem there is no gettin around this one, time for a split. Really is much easier than you think. Any and all quetsions you may have guys on here can answer.

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Also perhaps when someone rebuilt the bottom end, a washer may have been left out or put in the wrong place which could offset certain gears.

And it looks like your bike has a torsion spring and then even another little spring in the tranny, perhaps if one is wore out or broke it might cause problems, and speaking you have an older bike, it just may be.

Does it ever pop out of gear when shifting quickly upwards hard on the throttle?

If so then like forshee said, probably a bent shift fork, but if the shifter lever is moving down a lot more than normal without much more force, that kinda sound odd to me, like there is extra play...which kinda sounds like a different problem.....

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Everything was running perfect before this problem arose. Around 20 hours have been put on the bike since the bottom end was rebuilt. The bike was not wrecked recently or anything else.

The bike never pops out of gear up shifting, not a single issue up shifting.

I am trying to stay away from splitting the cases. It just does not seem to me it is in the trans, but I have been wrong before.

Interesting thought ForsheeMS, about the cases being worn around the shift fork shaft. Is that a common place to wear on these bikes?

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I had a friend yesterday help me out. She shifted the bike up and down for me while I spun the rear tire and watched the shifting mechanism. It had problems everywhere. It would stick halfway between gears. To get it unstuck, you would have to shift once the other way then go back down/up. The trans would stick halfway up and down shifting.

I have started disassembiling to split the cases. I am still pensive about doing so, but would hate to have any down time during the mx season. The test I did yesterday makes me believe I have bent shift fork or chipped shift drum.

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P.S. use a case splitter

And use the crankshaft setting tool when re-assembling

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