HELP...Transmission Question

5 replies to this topic
  • Ricks426

Posted August 03, 2011 - 06:00 PM


After 10 years and at least 10 000 kms of rippin on my 2000 YZ426F with nothing but just preventative Maintenance, I munched something in the transmission. It is stuck in gear and will not roll. Took out the clutch plates, and I don't see anything unusual. Have not pulled clutch basket out yet and I read on the internet that some of these bikes had trouble with shift forks. I was wondering, if it were the output shaft, gears or shift forks, can the gears be pulled out with the engine in the bike? and does the whole engine have to be disassembled? (head, cyclinder) Anybody have the same experience?
I now know why my chain was jumping (slapping) so violently. NOT just regular Chain Slap!

  • korosys

Posted August 03, 2011 - 06:34 PM


to get to them i am sure you have to pull the engine out and pull the jug off

  • grayracer513

Posted August 03, 2011 - 09:21 PM


Have to split the cases to do the trans.

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  • Ricks426

Posted August 04, 2011 - 01:15 PM


I was afraid of that....looks like full rebuild time:(

  • Ricks426

Posted August 04, 2011 - 01:47 PM


When I do the rebuild should I upgrade my valves to the 2001 titanium ones, cause mine has over 5000 miles on stock settings and would imagine they are stretched. It has never been adjusted (valves) What is the best type of piston and rings for my 2000 YZ426F? And will I have to do anything with my valve seats with new valves?

  • grayracer513

Posted August 04, 2011 - 03:43 PM


Valves don't stretch, they wear at the faces and the seats. Before you decided they need replacement, check the clearance. If it's still good, you don't have to do anything with them. If they only need to be moved one shim size in order to be right, you don't need to replace them.

If I owned a 426 and did need to change the valves, I would use the 2000 stainless valves instead of the Ti valves, even if it was an '02. The OEM SS valves and springs are dirt cheap compared with the Ti valves, and they're every bit as good. 'Shame they don't fit 450's.

Any time you change the valves you need the seats refinished.

IMO, the best choice for piston and rings is OEM Yamaha.

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