Yep, sounds like the engine is just too tall. I have an extra frame just laying around that I am looking to mod for a big engine. I'll keep my eyes open for the yz 490 or yz 400
We have a YZ 490 air cooled bike sitting in the junkyard, I think that motor would be an easier fit, dimensionally I think they are alot closer & no water cooling to contend with.
and its not in a blaster why??