It fits better than I thought....

[cutting torch]

'87 KX500 in a '92 KX250 frame:





The swingarm pivot and bottom case mounts line up, and leave the exhaust port pretty well placed in the frame, although the top pipe springs might be a bit tight. I'll have to cut the forward case mounts off the frame and relocate them, but thats easy.

I do wonder though, as much as a bike engine is bolted to the frame, is the engine helping the frame, or is the frame helping the engine?
 

torch

[sintax]

yea, i felt the same thing when i first got my 500 engine in the 250 frame. Just kinda looked like it was supposed to be there. Looks good! Wrap her up. Hopefully it does not take you 3 months like it took me.

[cutting torch]

3 months? Surely you jest! I'm thinking more like a year or more.

My goal with this project is have the end result as close as I can reasonably get to a new bike in appearance and function. That means there will be a lot of resto work added to the load, and also some suspension revalving.

torch

[AJ]

'87 KX500 in a '92 KX250 frame:





The swingarm pivot and bottom case mounts line up, and leave the exhaust port pretty well placed in the frame, although the top pipe springs might be a bit tight. I'll have to cut the forward case mounts off the frame and relocate them, but thats easy.

I do wonder though, as much as a bike engine is bolted to the frame, is the engine helping the frame, or is the frame helping the engine?
 

torch

the engine,  in this type of frame,
is certainly used as a intregal part and brace in the frame.


think of it,  as a 65 pound frame brace.
with the frame specifically designed for using it.