[Fox85]

Look out for the total height of the engine- most big swaps require either modification of the throttle body/intake, frame backbone, swingarm mount, or any combination of the three. My cbr250 swap involved #1 and #3.

 

[Fox85]

If you get a complete totaled bike it may be cheaper, but getting all the parts from eBay separately is often more expensive than buying and putting together a BBK, even ones that require splitting of cases.

 

[Fox85]

Fox. How did you like the 250. How long and how hard was it to get in? I was going to do the 250 but figured it wouldnt be a big enough reward for the work. How's the 450 coming along?

The 250 is great, probably 80-100 hours of fitting and total build. I have less than that, probably half that time but the previous owner had done a few things I didn't have to redo. I currently have it for sale to finance my 450 build (I need to find a donor bike) but I may pull the ads so I can ride the 250 at the crawl.

 

[Fox85]

The cbr300 would be a great build, if I were to do it over I would get the later model 300- same cases, more power

 

[Fox85]

My bike is 36.6 lbs heavier than a stock Grom- keep in mind you will pay an even higher weight penalty with the 500 engine.
Edit: extra 19 lbs according to the 500 build thread referenced above.

 

[Fox85]

Previous owner was 309 antonios, I continued his build thread when I purchased the project. I only had a few hours each weekend to work on the bike so the thread is not nearly as detailed as it should be.

 

[Fox85]

One issue with the 500: the throttle bodies. I was able to mount my single throttle body on a 90 degree intake- you'll need to modify the frame backbone to clear a dual throttle body.