man im very jealous,ive went through a few yamaha yz 250f motors like that,had jesse at williams motowerks do my head work had trans under cut falicon rod welded crank an its just awesome when you finally get to ride it,im planning to go through my 750k k1/k8 hybrid an build something similar,i must ask what carbs an pipes are you running.im thinking about going with cycle x 2-1 manifolds an running 2x32mm keihin fcr carbs from a crf 150,an i will be watching this thread very interesting