Maybe someone can help me with this one. I have looked at the diagrams but cannot find any one part that could be causing this. When under 1/2 throttle or more it will downshift on its own but only when in thrid and fourth (go from third to second or fourth to third.) Under normal cruising around conditions no problems. Hard bumps don't affect it either. Only under acceleration. I have had the ATV for about two weeks now and this is one of the reasons I got it, that and it was free. The guy who had it did not want to mess with the trans.

 

sounds like a shift selector, but im not completely sure

 

Is there any way to get to it without splitting the case?

 

A long time ago we had a 94 400 and it did the same thing, when going up a steep hill, and it was grunting it would kick down like an automatic. it also did it with a load fo rock driving through the field under load.

 

Not too sure, most atvs will have to have the cases split for that, some motorcycles only have a cartridge style trans where you can pull it apart without taking the entire motor apart. If I was you and going to do it, then I would plan to bore the cylinder and replace the piston and rings at the same time(the while I was in there factor, as well as refreshening the motor for a new lifetime.)

 

Does anyone know if the detent spring that holds the shift drum in place is accesable when the clutch cover is removed. /the more I thought about it I need to start there but I need to know how to get to it.

 

bump

 

Update: I removed the side cover. Inside there is a lever with a wheel on the end that mates to the drum star wheel. The spring was not holding the wheel tight to the drum anymore. It sat in a shed in neutral for two years. I think that is why because the neutral position puts more more load on the spring. I removed it and bent it straight again to test my theory and it has stayed in gear since. Hope this helps anyone in the future with the same problem.