2000 426 Tranny problems? Bad year??

I've noticed alot of the earlier 426's are having transmission problems, I was curious if Yamaha has made any updates on the replacement parts to fix the problem or is it 'just throw new parts in and set your timer on your stop watch to know when they'll be breaking again?' My Bro had just gone through this engine last year (Had 3rd gear problem) rebuilt damn near the whole thing, then he didn't ride it because he bought a new CRF450. Gave the bike to me and 25 rides later I land off a double and the engine start's knocking and the clutch feels funky. Now that I have the engine out of the bike it seems the transmission has alot of play in it. I can turn the shaft that the clutch basket sets on, A 1/4 of a turn before the drive sprocket starts to move (with it in gear). I noticed the transmission seemed loose once the engine started knocking. Anyone that has had transmission problems, please send your 2 cents my way. :devil::thumbsup:

Man, there sure were a boat load of problems with the 2000 transmissions when they first came out. If all the data made the many transitions that TT has made during the many vendor moves since then, you should be able to do a search and get a wealth of information. That's exactly why I waited to upgrade from the 400 to the 426. There should be a small bit of play in the shaft but 1/4 inch is excessive.

Bonzai :thumbsup:

Do you mean you can twist the clutch shaft slightly before the countershaft starts turning? In some gears there is play between the dogs between gears, which will allow some slop, which it sounds like you are feeling. Since this is a 2000, have you done the clutch plate fix and checked the counterbalancer shaft keyway? The keyway on the crankshaft has a tendancy on 2000s to loosen up (actually the key shears), which will cause knocking.

Yeah, I can turn the clutch shaft a 1/4 of a turn before the counter shaft starts to move, the trans felt loose once the engine started knocking as I was riding it back to my truck. I will check the counter balance too though...good idea. What is the clutch fix you are talking about? Thanks. :thumbsup:

I was about 10 miles from Sparks when this happened... (cold springs valley).

What is the clutch fix you are talking about?

00 YZ 426F clutch fix

the 1/4 turn of play is normal. As sparks said, its the backlash in the dogs. When you pull it apart it will be clear why this is the case.

Ok, I finally had time last night to tear it apart. Now that I have no hair left since I pulled it all out trying to find something broken. The counter balance is fine, it was tight and it looks like it was already updated, it has splines instead of a keyway. I pulled the cases apart and inspected the tranny, nothing is broken, chipped or worn. All the bearings in the cases are good too. The piston still looks like new, the camshafts are in great shape, the timing chain and crank drive sprocket looks fine. Is there anything else that has gone wrong with this year engine that I haven't checked? :thumbsup:

ok here goes-bad knocking noise----look at the key that goes on the right side of crankshaft behind gear on crank--also the gear itself that mates with counter balancer----i tore a motor apart looking for bad noise--always something new---look at all keys and gears for that matter----

ok here goes-bad knocking noise----look at the key that goes on the right side of crankshaft behind gear on crank--also the gear itself that mates with counter balancer----i tore a motor apart looking for bad noise--always something new---look at all keys and gears for that matter----

The thread is over 3 years old, I'm betting the original poster already has it fixed.

The thread is over 3 years old, I'm betting the original poster already has it fixed.

Yep, Sorry I didn't check back, I did finally find the problem. Turns out there was a piece of a gear tooth left in the cases from a previous repair, that piece just happened to dislodge itself (when I cased a double) and go through the counter balance gear's. It didn't break any teeth of of those gears just distorted the teeth enough to make noise. I dumped a bunch of parts in the engine while I had it out and all apart, tranny bearing's, couple of set's of gears, shift forks, updated crank and new bearings, higher comp piston, 450 auto decomp cam ect ect. bike runs awesome and hasn't given me any problems since :cool: Now my Wife bought me a 08 for Christmas, so this one will be collecting dust once I figure out the jetting on the new one...:applause::busted:

Thank you guys for all the help and info!!

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