Putting a YZ transmission into a WR

I have a 2003 WR450f and damaged the transmission. I have searched online for an affordable used transmission and have only come across a YZ and not the wr tranny. Is it a perfect swap ?

Can I simply remove my old wr transmission and pop in a YZ transmission and get a smooth working bike once again?

It will most likely fit but the gearing will be different.

I know the shift forks are the same part numbers.

I have a 2003 WR450f and damaged the transmission. I have searched online for an affordable used transmission and have only come across a YZ and not the wr tranny. Is it a perfect swap ?

Can I simply remove my old wr transmission and pop in a YZ transmission and get a smooth working bike once again?

isn't the yz tranny for 2003 a 4 speed?    

It shows 5 gears in bikebandit

it will work, but you'll get the close ratio yz gearset, not the wide ratio wr gears...

my friend has an 03 yz450f.  it's a 4 speed

my friend has an 03 yz450f. it's a 4 speed

Your buddy toasted his 5th gear,, that's why he thinks he has a 4 speed. Sure I believe him he really does have a 4 speed.


2003 Yamaha YZ450F Specs              

    Engine:Type: 449cc, DOHC, 5-valve, liquid-cooled four-stroke w/ titanium valves

Bore x stroke: 95x63.4mm/3.74x2.5in

Compression ratio: 12.5:1

Carburetion: 39mm Keihin FCR Flat-side w/TPS

Transmission: Constant mesh 4-speed, multi-disc wet clutch

Starting: Kick

Edited by DeepPurplishBlue

You will have to change the mainshaft that your sprocket bolts to ad the pinion for first gear is machined into the shaft.

Depending on what you use the wr for a yz swap may or may not be right for you-

If you ride technical trails or tight single track the yz first gear isnt ideal- if you ride the bike on the road the yz 5 th gear is shorter than the wr.

On my 07 i built a hybrid yz/wr transmission using the yz 1-2-3 and the wr 4-5 gears.

My bike is a street titled motard that sees track time. The yz 1-2 gear is perfect compared to the wr on a closed course- with the wr 4-5 gear i can still reach above 100 mph on top.

I would buy the oem gears and fix the gearbox. Close ratio sucks in the woods with a lot more shifting and feels like a dragster than a solid tractor.

Close ratio sucks in the woods with a lot more shifting and feels like a dragster than a solid tractor.

Thats a great explanation.

The transmission is really yamahas weak link in these bikes to be honest- if it were me i would take underground's advice and buy new because you could potentially be going through this again in the nearfuture with used parts.

Solved it. Apparently mistakenly mounted the housing for the starter in reverse this changing the polarity of the magnets causing the starter to work in reverse. Turned it the right way now and works fine.

Thats a great explanation.

The transmission is really yamahas weak link in these bikes to be honest- if it were me i would take underground's advice and buy new because you could potentially be going through this again in the nearfuture with used parts.

i have a wr450 and a yz426. the close ratio gearbox is what makes the YZ the worst bike i have ever owned

The '03 WR450 is a Gen1 450.  The only bolt-in transmission swap for this bike from any YZ450 is the Gen1 '03-'05, and that is a 4 speed.  Won't do any good to argue that it isn't; it is.  The shift forks are not the same part numbers, either; there's only two of them, vs. 3 in the 5 speed, and obviously the shift cam is also different.

 

It is possible to install the 5 speed from a YZ426, but you'll be doing some machine work to make it fit. 

Deleted response..

Read the whole thread, the problem was solved.

Edited by zibbit u2

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