09 yz450 thinking about converting to wr450 trannsmission

I converted my yz450 to street legal. I used the wr450 crank and flywheel ect. to run the lights. I didnt cut any corners to build this bike. Now the issue im having is I cant change the sprockets around to get bottom end on trial and top end for highway without reving the engine out. I would like to know if I use a wr450 tranny if I will get both? I think first gear is lower and last is higher but im not sure? Also as far as I can tell all the gears are different and one shaft is different? I dont want a loss of power. My buddy has a cr450X enduro and its a dog compared to mine. I just need as much advice as I can get. $500 just for the parts to change is alot so I wanna know if its gonna make an improvement. Thanks for the help.

It's a pretty powerful bike, you might be able to just swap out fifth gear...you'll have the ability to do the trails, and still cruise the superslab!

So what would I need just both gears for 5th out of the wr450? And that wont cause any problems with the other ratios?

You're not going to want to change only 5th. If you are OK with first gear being on the tall side, you can change 4th and 5th to the WR parts and then you end up with a 1st four gears exactly like the old 4 speed 450's, but with another gear on top. Or you can change the entire gearbox and have a lower 1st and second.

The parts have to come from an '07 through '11 WR. I haven't checked, but the '12 would likely fit as well. The YZshift forks work. Read:


Ok thanks a lot

I have this question too,

a "friend" has prepped a dakar YZ last year,

he used sprockets from different yamaha's, 250's WR's etc..

Ill look it up, but is best to leave to pro's to change gears..

he warned me that its not an easy job..

he warned me that its not an easy job..

It does require the cases to be split, but it's no harder than working on the stock trans.

I have a 2010 yz450f that is also street legal I am running a 13 and 51 and it's not running very hard at 60 mph on the street I am unsure why this is an issue?

Your 13/51 setup is turning right at 7500 RPM in 5th at 60 MPH if you assume (if unrealistically) that there is no wheel slippage. That's a bit much for any sort of extended road use.

With a WR top gear and a 13/48, that drops to about 6400, still kind of high, really.

Also, to those considering this, a hybrid approach would use only the top two gears from a WR, resulting in the same exact first 4 ratios as an old 4 speed YZ450 had, plus the 5th.


for enduro "use" a whole lot of gear need to be changed,

cant acces my other computer, its on there.... (sorry)

But 1st is way longer, as I recall,

5th is probebly of a WR, but not very sure..


Im changing sprockets too on the bike, that's the easiest solution for now, and run enduro mode on the bike.

not going to risk my piston or change it every two months (20 -ish hrs)

I installed the whole WR transmission into my 08 YZ450. I ride/race a wide variety of terrain, and the low first gear is nice a lot of the time when I am practicing or racing a real rocky race (think boulder wash). If I had to do it again, I think I would go with the whole transmission, if funds allow. I run 13/50 gearing and run from the open desert to the motocross track to tight first gear stuff in the same week, and changing gearing never crosses my mind.

But, if your primarily using it for street use, and first gear is alright for you now, I would just install fourth and fifth, like recommended above. For me, it worked out better to run the whole WR transmission, but I am asking for a lot of versatility out of my bike.

Okay 7500 is a lot I did not realize I was turning those kinds of R's. So I guess my next question is why would you not just get a WR and uncork it? Are there still big advantages to having the MX bike?

That's a whole basket of different issues. Weight, suspension, and engine performance are on top of the list of why a YZ over a WR. Even an uncorked WR is down about 4-5 hp or better on a YZ450.

You may want to read this thread: http://www.thumperta...235#post8107235

right on thanks for the link

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