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Putting a YZ transmission into a WR


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16 replies to this topic
  • aldean

    TT Newbie

4 posts

Posted September 20, 2016 - 05:35 AM


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?

  • cjohnso

    TT Newbie

6 posts

Posted September 20, 2016 - 05:58 AM


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

  • ttreewalkerr

    TT Bronze Member

147 posts

Posted September 20, 2016 - 03:47 PM


I know the shift forks are the same part numbers.

  • Just_a_trail_rider

    Get Help Now

6,870 posts
Location: California
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Posted September 20, 2016 - 05:28 PM


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?    



  • cjohnso

    TT Newbie

6 posts

Posted September 20, 2016 - 06:23 PM


It shows 5 gears in bikebandit

  • bikedude987

    TT Silver Member

543 posts
Location: Arizona

Posted September 23, 2016 - 01:26 PM


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



  • jamesm113

    TT Bronze Member

191 posts
Location: California
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Posted September 25, 2016 - 09:15 AM


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



  • ttreewalkerr

    TT Bronze Member

147 posts

Posted September 25, 2016 - 11:22 AM


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.

  • DeepPurplishBlue

    TT Bronze Member

386 posts
Location: Texas

Posted September 25, 2016 - 12:04 PM


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, September 25, 2016 - 12:51 PM.


  • jamesm113

    TT Bronze Member

191 posts
Location: California
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Posted September 25, 2016 - 12:29 PM


http://www.partzilla...SION/parts.html

 

There's no 5th gear.  Not sure how big of an issue it will be for OP.  My buddy could still keep up in the open washes



  • knuckleduster271

    TT Bronze Member

236 posts
Location: Ohio

Posted September 26, 2016 - 05:35 PM


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.

  • underground-mpyre

    TT Bronze Member

276 posts
Location: Indiana
Garage View Garage

Posted September 26, 2016 - 06:12 PM


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.

  • knuckleduster271

    TT Bronze Member

236 posts
Location: Ohio

Posted September 26, 2016 - 06:33 PM


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.

  • aldean

    TT Newbie

4 posts

Posted December 14, 2016 - 05:02 PM


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.

  • dg400sm

    TT Bronze Member

369 posts
Location: Thailand

Posted December 15, 2016 - 03:56 AM


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



  • grayracer513
43,168 posts
Location: California
Garage View Garage

Posted December 15, 2016 - 02:55 PM


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. 



  • zibbit u2

    TT Bronze Member

412 posts
Location: British Columbia

Posted December 17, 2016 - 12:45 AM


Deleted response..

Read the whole thread, the problem was solved.


Edited by zibbit u2, December 17, 2016 - 12:47 AM.





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