Re: Stiff engine
hi; rog; pull the head fasteners, the head and the bbl. this way you can make sure. also dont rebuild with hardware from the kit. replace all hardware with american stuff. use red and blue locktite when reassembling. if you have a dremel its time to match the exhaust pipe with the gasket also replace spark plug and wire. sick bikes has an air cleaner that will let your engine breathe. i dont know why your engine would tighten up with the right gas/oil ratio unless you have a leaking gasket.