WR400 frame with 450 motor...

Here is the deal... In Quebec we have a licence plate rating by cc and anything under 400 is WAY cheaper to plate and insure...The go by model/seriel number on the frames. So anything in a 400cc frame and i'm set

I want to built me a little motard for fun rides that would double has a woods machine once in a while.

Does the more recent WR450 motor bolt into a WR400 frame? If not, alot of mods would be required? I'm a decent welder/fabricator, I would not be worried about that part but if someone has already been down that path before any hints would be appreciated.

Sorry I haven't tried that setup. But this sounds like a really interesting project!

However if you need measurements, I own both a 00 WR400 and an 03 WR450. I would be willing to measure both as long as I don't have to disassemble anything.

Hopefully, somebody has done this and knows all the ins and outs.

will not bolt up. modding needed.

This is what l done.

First l had to cut off the rear sump guard mount so the engine would sit right.

The spindle that goes through the swinging arm and engine is bigger for the 450 so l had to get a sleeve made up, didn't cost much.

The bottom engine engine mounts need to be moved forward or what l did was file out the bolt holes and use a smaller engine bolt.

The top engine mount on the 400 has 3 bolts through the frame where the 450 only has 2, you'll have to use the 450 brackets and cut off the front bolt hole from the frame, l was going to just leave it unused but found because the 450 has the coil built into the spark plug cap there's not enough room to get the cap on and off other wise.

l've fitted a battery in the airbox strapped to the lid and drilled some holes in the airbox because the battery takes up a lot of room.


This seems like a no brainer but

why not just use the 400 engine?

This seems like a no brainer but

why not just use the 400 engine?

The motor swap seem like a lot of work for a bigger displacement. Why not install a big bore kit? If you can weld why not cut the numbers out of two frames and swap them? I wonder if that is legal? :banghead:

My California street legal 99 Wr400 will pull 3rd gear wheelies with my 230# body on it and top out at 85 MPH, I wonder what the 05 Wr450 will do? I have thought about buying an 05 450 and swapping frame numbers but the DMV also has the motor number. I would have to file paper work for an engine replacement. I just got my 400 dialed in and running great, I would hate to have to start over again with all the free mods...


modded 400 is good. but a modded 450 is WAY better. chassis and motor!!!!!!!!!

If you can weld why not cut the numbers out of two frames and swap them?

This is a really good idea, IF you know a good frame shop.

I had forgotten that years ago, when I lived in a state that didn't allow any bike to have a tag that wasn't street legal from the factory, I did the same thing with an XT350 and a TT350. The XT was completely worn out so I bought it and had a frame shop swap the steering stem housings between the 2 frames. Viola! A street legal TT350. It worked so well, my buddy did the same thing with an XL350/XR350.

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