Gearbox problem yz125

Hi guys. I have a problem with my 05 yz125. I cant shift up to 4th gear. The first 3 gears works fine but when i try to shift up nothing happends. Does any one know wich part in the tranny who might cause my problem ?

Either a bad 4th gear or bent shift fork would be my guess. What happens when you try to shift? Does it not even let you lift the lever or does it just not go into gear when you lift the lever?

I can't really see any damage on any gears. I can move it up a bit but i does not jump in to gear. It feels just like 3d is the highest gear. :smirk:

How did the oil look when you drained it?

With the minimal info, i agree with ftball, it sounds like a bad shift fork or 4th gear.

What happened to cause this?

The damage you are looking for on the gears in on the engagement dogs.

Between my brothers 2 05 YZ125s and mine we have both experienced not being able to shift from 3rd. It isnt a chronic problem, but happens on occasion. cant find anything wrong with them

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