WR tranny in a YZ

[09KLX250]

Can a WR400F tranny be used in a 2000 YZ426F? I use my YZ as a dual sport and would like an overdrive set-up so I can run 14/49 sprockets and still be able to cruise at a decent speed (55-60) without maxing out the rpms. Could I just swap out the 5th gear set? YZ 21p/20g WR 25p/21g

[426 NOOB]

Can a WR400F tranny be used in a 2000 YZ426F? I use my YZ as a dual sport and would like an overdrive set-up so I can run 14/49 sprockets and still be able to cruise at a decent speed (55-60) without maxing out the rpms. Could I just swap out the 5th gear set? YZ 21p/20g WR 25p/21g

it can be done with a wr 426 gear set and parts. Not sure if 400 trans will work in 426 though. This thread was in the sticky at the top of the page and talks about the swap. Also, i think you have to swap out all or most parts to make it work. You cannot just change 1 gear.

https://www.thumpertalk.com/forum/showthread.php?t=315799&page=2

[09KLX250]

Thanks for the help.

[426 NOOB]

no problem

[pscook]

Can a WR400F tranny be used in a 2000 YZ426F? I use my YZ as a dual sport and would like an overdrive set-up so I can run 14/49 sprockets and still be able to cruise at a decent speed (55-60) without maxing out the rpms. Could I just swap out the 5th gear set? YZ 21p/20g WR 25p/21g

Don't change just fifth, the jump between 4th and 5th is too big to make it useful at all. I dropped a complete WR400 trans into my 2002 YZ426 after trying the WR 5th gear-ectomy (way too tall, completely useless), no issues or worries. Both shafts fit great, I had no fitment issues during installation and the runs that I have made with the WR trans have been really nice. Quite the monster in the woods, the Rekluse clutch helped with that a bit, I suppose.

For what it's worth, the only difference in transmissions (besides gear ratios) is 1st gear, as it's machined into the clutch output shaft (drive shaft). Everything else, dogs, drum, gears etc, is interchangeable. This is for 400/426 models only, I don't know about the 450 models. If you change internal gearing you need to change gears in sets, not just one side. So, you would need both drive and driven (gear and wheel?) gears to change ratios. But you can change just one ratio set at a time if you wish. I also think that the YZ250 2t sprockets fit as well, but don't quote me on that.

And, if you want great cruising, use a 16/38 combo, that is pretty nice to keep the RPM's low while on the road. I happen to have a good selection of street gearing for sale in the classifieds if you are interested. I think that you can hit 130MPH (on paper) with that gearing and a 17" rear wheel.

Ask me any questions about the transmissions, as I have been in there three separate times playing with my ratios. Gonna go in one more time and hopefully I will get it right this time. I hate splitting cases.

[09KLX250]

Good stuff, Thanks!!

[LEMMON1]

hmm i have a tranny that i need to replace in my 426 now since it locked up today...maybe i should consider wr gears just in case i wana make it a motard bike later

[pscook]

hmm i have a tranny that i need to replace in my 426 now since it locked up today...maybe i should consider wr gears just in case i wana make it a motard bike later

I really like the WR gears for Motard, as the YZ were too tall. I had to gear it for the straight sections, and that made the YZ 1st gear taller than the WR 2nd. Where I used to putt through the dirt in 1st with the YZ gears, I can now use the throttle in 2nd gear with the WR gears. Great improvement, especially for SM. It was much better in the woods as well (duh), not a big surprise there.