WR 4th & 5th on a 10 YZ450f?

Just curious. I am in the mood for a little more up top. I recently installed a cylinder works 468 kit, I know it is not much of a hop up, but it pulls a little harder thru out the gears. i love the snatch of 1rst thru 3rd, and was wondering if i replaced 4 and 5 with the WR, would it drive out a little longer from the longer gears and is the tear down be worth the effort. 5th gear tends to be a little jumpy, so i need to possibly change that one out anyway and i thought while i had it tore down......what the heck, throw some WR into the beast and see what happens. Does anyone out there have an opinion about this?, has it been done before?, and what are the pros and cons if any?.

lastly- if i have a 10 yz, what year gears from the WR will work? thanks thumper buds!! :thumbsup:

The '10+ trans is 90% the same parts as the '06-'09, and the WR gears fit those. I feel reasonably certain that they will fit.

The idea of using a WR 4th and fifth has intrigued me for some time now. It would be exactly as if you had a YZ450 4 speed with the WR 5th added on. Should be a very cool mod.

I've had one in my 2010 450 for about 6 months now. Unless you are racing supercross, it is the perfect gearbox for a YZ 450 ......PM me for parts and details....(I'll have to look them up) seems like with a good guy discount, it cost me about 225 bucks or so.( I did the labor myself)

I am stoked to try this out. what are all the parst that i need. i know each gear has two parts, but i dont want to order to much or too little at the same time. thanks thumper buds. I am looking forward to pulling hard and hauling a$$.

i just looked up a few parts

09 WR 4th gear has a 20T pinion, 21T wheel.........the 10 YZ 4th gear has a 22T pinion, 24T wheel.

it seems to me, in my uneducated guessing that the yz should pull longer then the WR in 4th gear.

09 WR 5th gear has a 25T pinion, 21T Wheel........the !0 YZ 5th gear has a 21T pinion, 20T wheel

I have no idea what that means in terms of longer shorter gearing??

i bealieve that these are the only parts i will need to do this sweet mod :thumbsup:

The parts needed are no more than the 4th and 5th gear pairs (pinions and wheels as the parts book calls them) and any bearings you think should be replaced.

Your stock trans ratios are

1.929

1.533

1.278

1.091

0.952

With the WR top two they'll be

1.929

1.533

1.278

1.050

0.840

Welp, i got all the parts.........and it turns out that fifth gear has different splines........so i have to order a new shaft......but i will make it work and i will post pics... :banghead:

The output shaft. Ah, yes, I see that the '10 uses a different output shaft and 5th wheel than the '06-'09 did. All the rest looks the same except the third pinion, which shouldn't affect anything. Check the fit and alignment of the shift forks too. I think what the difference is is that the shift cam is larger so the forks are all different. But being that the '10 fourth gear and most of the rest of the trans has '06 part numbers, you should be OK.

Looks like I didn't look into this deep enough, eh? Keep us posted.

I didn't know that the yz and wr shared the first three gears. I bet the yz450 would make an awesome offroad (enduro) race bike where you spend a lot of time in 3rd. Well... at least in the desert where the racing isn't really that tight. You'd just have to detune it a bit.

Good info for when I am ready to upgrade my ktm race bike.

Edited by mauricedorris

I didn't know that the yz and wr shared the first three gears.

They don't. The WR box has a considerably lower first, a lower second, and a nearly identical third.

They don't. The WR box has a considerably lower first, a lower second, and a nearly identical third.

Sorry, I misread the post above.

I am still planning on considering the yz as offroad race bike for the desert (assuming that there's any desert racing left in a couple of years)

I love the ktm, but I really miss the Yamaha reliability.

...t I really miss the Yamaha reliability.

That truly is an endearing feature, is it not? That's one of the big reasons I'm on one.

My YZ450 works out very well for desert racing. No reason to de-tune it at all. The shortcomings it has are the close ratio gearbox, which we are talking about here, the lack of an e-starter, which is really only a big deal on the starting line, and not always even then if the bike is tuned right and you set it up right, and the lack of enough electrical supply to run lights. What I'd really like to do is find a complete crashed WR someplace so I could pick and choose parts from it.

The 2012 WR is a very tempting piece.

That truly is an endearing feature, is it not? That's one of the big reasons I'm on one.

My YZ450 works out very well for desert racing. No reason to de-tune it at all. The shortcomings it has are the close ratio gearbox, which we are talking about here, the lack of an e-starter, which is really only a big deal on the starting line, and not always even then if the bike is tuned right and you set it up right, and the lack of enough electrical supply to run lights. What I'd really like to do is find a complete crashed WR someplace so I could pick and choose parts from it.

The 2012 WR is a very tempting piece.

My recent engine rebuild on my KTM has me thinking blue again.

For desert racing, I don't see the tight gear box as a short coming. Nothing better than having two gears for a situation. But... I prefer the more technical races (enduros, H&H) where you spend quite a bit of time in 3rd and 4th gear and less time in 5th. The lack of an estart is not a problem. I have a ktm that lacks a kick starter. That isn't a problem either. So long at the bike starts, who cares how.

Yes, the new WR is intriguing. I know it rides light, but the overall weight is still a bit much.

Edited by mauricedorris

The close ratio box is a bigger problem at low speed than high most of the time even where I race. I only really wish I had more top end about 4 times a year, but when you've been cringing at listening to your engine spin at nearly ten grand for a quarter mile and somebody on a big orange thing rolls by you, it's a big deal, at least in that moment.

The low speed end of things I handled with a Rekluse, and it's no longer a problem. And you're right, close ratio boxes do have advantages. That's one reason I think the mixed gear box we're talking about would be so ideal.

williec,

Did you ever finish your trans project? Some of us are still on the edge of our seats.

Edited by PilotHonda

Sorry to leave everyone hanging. I competed my project swap about two months ago and I love it. The 10 yz fifth gear has different splines on it then the 09 yz and wr. This was the only issue I ran into. The fix to the problem was to just get a older model output shaft......the one the sprocket goes on. Luckily for me my brother blew his 09 yz and I comendered his shaft. I left forth gear as it was on the 10 yz but swapped for the longer wr fifth. The parts that I ordered where fifth gear for 09 wr (both gears,there is one for each shaft) and the retaining ring and stole my brothers 09 shaft. All other parts are interchangeable and slid into place perfectly with a little grease and patients. The yz/wr hybrid rips.......it has quick excelleration and a much higher top end. In my personal opinion it is the bestof both worlds.

Thanks for coming out of hiding willie. We appreciate the feedback.

Edited by PilotHonda

It's good to know that worked out that easily. Now we know what the difference actually is.

My preference would be to use both 4th and 5th from the WR, as I suggested earlier. The result would be almost exactly the same first 4 gear ratios that the '03-'05 4 speed had, but with the addition of the high 5th gear on top. To me, that would be an almost perfect desert race box. As it is, at cruising speeds, there's not a lot of difference between 3rd, 4th, and 5th. Seems like the jump from the YZ 4th to the WR 5th would be kind of extreme.

As I noted in an earlier post, this (WR 4-5th) is the perfect gearbox for the 2010 (and earlier?) for anyone not racing supercross....The Rekluse overcomes any issue with the YZ taller 1st gear..and one can loaf at 55 in the sandwashes......I run a 13-52 on my '10.....

Hi All, I'm looking at doing a full WR gearbox swap into 2010 YZ450, do we know of anyone that's done the full swap?

 

I've done some searching and apart from the actual gears and pinions and the main and driven shafts the only other differences in the part numbers between the 2012 WR450 and the 2010 YZ450 are nos 11 and 19 in the wr parts fiche Pt. No. 93306-00431-00 (the bearing on the gear shift side of the main shaft) and 90209-21332-00 (a washer that sits between 3rd and 5th gears).

 

The bearing may be an issue if the outer diameter is a miss match for the YZ case and I'm not certain on the actual dimensions of the main and driven shafts. Any help appreciated.
 
Thanks, Hayden
Edited by clevochild

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