I've been trying to learn some differences in the heads used in the CRFs. The 04 05 trx. And the 06-14 trx. I know the 06 to 14 trx uses 36mm intake valves with 5.5mm guides. And 30mm exhaust valves with 5.0mm guides. With that being said. Does anyone have these specs for the CRF heads and the...

Hey guys, doing a head gasket job on an 08 and I noticed what looks like an o-ring on one of the head studs near a dowel pin? Never been inside one of these engines and not sure if this is normal? Seems very odd and only see it on one dowel? Any idea if this is normal? Top right in picture.

Looks like I’ll need a new head gasket, found milky oil and radiator bubbling when it’s running and revving. Went ahead and tore it down, looks like the gasket may have separated/lifted itself from previous repair persons job. Is OEM the best to purchase?

Build finished retro 450 r 480 stroker with je12.5 rage head hc3 and 44 mm fcr and cfm air box Colour scheme from 1986 atc 250r

so i got 2007 trx450er and recently my valves were out of spec so i had given my quad to a friend of a friend who said he knew what he was doing, i got the quad back and put all new fluids but my battery was dead (it had just enough voltage to start the quad once for a few seconds of idle then...