1994 YZ250 1st gear grinds, doesent engage, all other gears work fine....runs great...just got it used bike dont know history......any suggestions welcome....thanks!!! :uh: :bang: :bang: :bang:
sorry to say - but you are going to have split the cases on that one. first gear is usually part of the main axle shaft - they can wear out so you have to replace the whole shaft.
First of all thanks for your reply to my first post!!! But as far as my clymer manual shows.....i can take the gear off of the shaft and change it....i also thought it was weird that the broken teeth never interfered with the other gears, dont you?....but about the shaft is that an exception on certain bikes.... or are some just different?
the tranny has gears on both the input shaft and output shaft meaning that a six speed tranny has 12 actual gears. I believe its the one on the input shaft you have to replace - the teeth don't always break off - they can simply wear down. go to yamaha's site www.yamaha-motor and go to parts..check the tranny out. at any rate, if you replace a gear on the input shaft, you should do the output as well - some will argue you should do the gear next to it especially if its a sliding gear.
What about a bent shift fork? If you have a shift fork bent and the gear is not getting pushed over all the way into mesh then you will have grinding and failure to mess will keep that gear from actually being useful. Of course if someone (you or the previous owner) have been trying to use it alot then the gears (first gears) probably are damaged.
Keep in mind that the teath of the gears are always meshed with the other gear. What moves in and out of position or the dogs on the sides of the sliding gears.
A bent fork would keep the gear from sliding all the way over so that the dogs fully engage. In this case, you'd feel the resistance (and some chattering) in the shifter as the gears would push back through the forks. In this case, I would expect that the bike wouldn't stay in gear (or never get into gear) and the sound would go away once you took pressure off the shifter. Either that or the dogs are so worn down that they just barely reach the locked gear.
Generally, the teeth don't wear down enough to allow the gear to just slip will it's in place. Since the teeth are always engaged, they don't take a big hit when you shift. It's the dogs that get beat up.
Not that it matters, since either way you need a new gear. Also, if the fork is bent, you probably need a new gear due to the damage that was caused by partially engagin the gear. Worn dogs is generally why bikes pop out of gear as well.
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