00' YZ 250 Tranny locks up and no neutral, looked at by 3 people but no luck.

[Leichardti]

Bought my 2000 YZ 250 2-stroke off my co worker for cheap knowing that it had some type of tranny problems. Wouldn't shift into neutral but would run.

My friend took it apart and found out two shift forks were broken. Replaced all three shift forks and checked all the gears. Everything looked good and appeared to not need anymore new parts. I also had another friend look over the gears and other tranny parts and said that it looked good. Once the tranny was back together and before closing the case, there was still a problem with it locking up at one point.

Took it to another friend who rebuilds many dirt bikes and he took the trans apart. Looked it over, looked good, changed piston and other small things. Close the case back up, everything worked fine but in first gear it would lock at one point.

Took it home, dropped it in, hooked up the clutch and everything and tried to roll it threw the gears. Now no neutral, locks in every gear but maybe the last two.

Any ideas or problems with these tranny? I guess I’m going to consider changing all the tranny gears and shafts. Hopefully fixing the problems. I’m just unsure because i had three guys with a lot of experience not have any idea what it might be. Besides a bent shaft or possible band gears.

Any ideaS?

 

[IndyMX]

Maybe a problem with the shift drum or the shift drum bearings??

 

[Matt90GT]

Either you have a gear in backwards, the shift drum has issues, are missing 1 more more shims in the gear shafts or have the shift forks installed wrong.

best bet is to get out the factory manual, match up each gear by counting teeth and go step by step putting it back together. Then so the same for the shift drum and forks. Also measure like the manual states.

You also could have gotten some wrong parts for the year of bike or superceeded parts that need more than one superceeded part to work properly -- ie you need a whole kit, not just 1 part.

 

[moto9]

Check the shift shaft to see if it's bent

 

[Charlie Mix]

Because you have found broken shift forks, you should have bent shafts (where shift forks slips).
You should also check the correct position of the three shift forks on their shaft and in the shift cam.
Any shift fork have a different mark (L, C10 and R).
Mesh shift fork L with the 4th wheel gear.
Mesh R shift fork with 5th wheel gear.
Mesh C10 shift fork with 3rd pinion gear (primary axle).
All these components (both the shafts with their shift forks and shift cam) shoud be placed in the left crankcase all together in the same time.
Check shifter operation before installing right crankcase, so you can eventually see what goes wrong.

I've almost forgotten to tell...place a dab of molybdenum grease on shift forks and shift cam before assembly.

 

[whenfoxforks-ruled]

Any of the above can be true. BUT, when setting the trans, I make sure its in neutral. While its in neutral, you set the drum, star, shifting shaft, and the spring loaded rollers on the outside. Then its all in sequence. If its not properly in sequence, it can cause shifting issues that you describe. Even the little pawls inside the star mechanism, they can be put together backwards. Did someone actually measure the width of the areas that the forks ride in on the gears? And I sure hope these people that have helped you, have determined the dogs are still good?

 

[Leichardti]

Thanks for all the information everyone. I have done alot of research, put alot of time and money into this bike and gotten no where.

I think ive decided to rebuild entire trans, while looking for what was damaged/real problems.

My last question is, could anything be wrong with the block/case its self? I dont want to rebuild the entire tranny and find out something else is wrong. Or rebuild it, and the problem comes back over a short period of time.

If rebuilding the tranny is 100% sure going to fix the problem? (and id make sure its installed properly)

 

[whenfoxforks-ruled]

The only way I could think the cases were bad, relating to the trans, would be the bearing races and the right side cover. A lot are set up so the cover is what keeps the shifting shaft from moving too far over, and that will put your selector out of sequence.

 

[sharky243]

Sounds like bent or broken shift forks to me. Possibly a broken gear or two.

 

[whenfoxforks-ruled]

He would have metal parts coming out of the trans oil?