Ok so turns out Australian model kymcos (where I live) where never restricted (boss,cdi) so no rev limiter I've been told and that's why my boss was smooth when it was brand new. I never took the crank out to do the big bore kit as it is only a top end mod not a stroker kit your idea on floating valves has got me thinking now because it is a bigger valve head that came in the big bore kit but then you would think it should be cappable of dealing with the bigger cc.