Changing the YZF gears to the WR wide-ratio gears......

[Chipstien]

IS it possible? I guess I should say that of course it possible. What is needed, just the gearset? Is 1st and 5th the only different gears or are they all different. I would just go out and buy a WR but I have too much into this and I am waiting for the aluminum frames anyway. My bike is set up awesome except that on really gnarly stuff I could use the lower 1st. However, if I am going to open it up then I might as well just do them all. ?

I need details..... who has done this? ?

[426mankiller]

This isn't official, but I compared numbers from the yamaha website just for kicks and the difference between a yz & wr trans was a different main axle, each gear of course and each gear's matching pinion gear. Those parts add up to $424.00 and who knows if it would actually all fit together. Until then I am installing a rekluse auto clutch and hoping that gets me through the next rock infested creekbed without stalling the bike and getting bent over the handlebars!!!

[cowboyona426]

You can put the WR 5th gear in for sure, I know of at least 1 member here who has done it, haven't seen him around for a while though (Maniac998). All you need is both 5th gears from the WR trans.

[Chipstien]

I too have looked at the parts list. In fact, I have all the transmission part numbers from 98 to 03 in front of me. Obviously 03 is out.... everything is different. But 98 through 02 are close. 98 and 99 WR's are identicle. 99, 2000, and 2002 WR's use the same main axle, 2nd gear pinion, 5th gear pinion, and 1st through 5th gear wheels. the 99 and 00 use different 3rd and 4th gear pinions while the 00 and 02 use the same 4th gear pinion but different 3rd gear pinion.

I suspect that the 00 needs to use the gears and pinions out of the 01 and 02 426's instead of the 400's however I really do not know. Maybe only the 2000 WR gears will fit the 00 YZ. I am stumped. ? Does anyone have the inside scoop? ?

[RPS]

See link. It sounds like Ty Davis is running a wr tranny in his YZ450F

link

[Heckler]

YZ450jack did it. He put the whole WR450 gear box in. He said it drops right in. I think he said it's about $700-$800 in parts though.

[Hick]

I suspect that the 00 needs to use the gears and pinions out of the 01 and 02 426's instead of the 400's however I really do not know. Maybe only the 2000 WR gears will fit the 00 YZ. I am stumped. ? Does anyone have the inside scoop? ?

I'm pretty sure that all tranny parts are the same from '00 through '02, I would be totally surprised to find that any one part would not swap, especially the gearwheels themselves. I know the ratios were changed for the '00 YZ but not if anything else was (I sort of doubt it). I'm also pretty sure the gearwheels themselves will also interchange with a YZ 250. ?

Obviously the entire gearset, WR into YZ, would be a direct swap, but you may also do a partial swap, the limiting factor will be whether the dogs with, for example, a YZ 4th gear mate correctly with those on a WR 5th etc.

Also, don't forget that 1st gear on the primary shaft is integral to the shaft itself...

Anyway here are the ratios for the 426 bikes, 1st through 5th in order:

WR

29/12

26/15

21/16

21/20

21/25

YZ

24/13

23/15

23/18

24/22

20/21

Here is the % difference (BTW the primaries are the same WR vs. YZ) in the YZ vs. WR (i.e. +% means YZ is that much taller, -% slower)

31% (so WR first is a granny-like 31% under-driven compared to a YZ. Oomph.)

13%

3%

-4%

-12%

The WR 450 has the same ratios as the WR 426, so it wouldn't surprise me if they share parts, but the YZ 450 is all changed (oddly enough 4th gear is the same as the WR).

Note that just because they changed the part number does not always mean the part itself has changed...

Hope this helps.

[rush66]

so if I were to do this mod I would need the gears from a wr 400 ?

[Hick]

so if I were to do this mod I would need the gears from a wr 400 ?

I can't be 100% sure, but what I do know is that I put '01 YZ 3rd and 4th gearwheels (among many other parts) in my '00 YZ. I ordered the '01 parts because they were available and at the time there was a rumor about casting/metallurgy flaws in "early batches of '00 YZ gears..."

?

For model years '00 through '02 I would be stunned to discover any significant changes in tranny components, so as far as I'm concerned you could order PNs based on the '00, '01 or '02 WR parts fiche and end up with (functionally) the exact same part.

Hope this helps answer your question.

[rush66]

thats what I was guessing since their are so many parts that can cross over. would it be to much trouble for someone to post the parts nessecary ? or anyone have a link to another post ?

[lbxr]

I put 01 parts in my 00 yz426. I had a skipping 4th gear and replaced 4th and 5th gears w/ wr gear sets and it worked fine. I should have done the whole tranny when I had it apart, but I cheaped out. Then a couple of months ago I decided to do it right and went back in and dropped in the wr 1st and 2nd gearsets. I left 3rd stock as it is the same or close to the ratio of the wr. I replaced 1st and 2nd because the gap from 1st to 2nd would be too wide if I just did first gear only. Works great w/ stock yz final gearing. Just got back from Moab and Grand Junction. Huge improvement for technical riding. My old yz 1st was about equal to my new wr 2nd gear. ?

[YamahaWR450FMike]

I think the 04 WR450 5th gear isn't all that tall. Really is what the WR450 needs is a sixth gear. I find myself trying to shift up above 5th gear all the time and I'm running a 49 tooth sprocket

[rush66]

so to make this swap work I just need the main shaft 1st,2nd,4th?,and 5th gears and pinions right ?

[Chipstien]

Judging from what I have gathered yes, you just need the shaft, 1,2,3,4,5 wheels and 2,3,4,5 pinions. The 1st gear pinion is on the shaft which is why you need it. As lbxr said, you really don't need 3rd wheel and pinion but when spending 350+ what is another 50. ?

[rush66]

yeah after pricing all the parts from bike bandit $370 anywhere cheaper? It might have to wait awhile, the close ratio isn't all that bad. But would it be awesome to have a higher top speed and a lower first gear. All wraped in the yz package.