[558KingR]

What id like to know is there a difference in valve sizes between the crf and the trx? I know Duncan Racing sells a big valve set up for the trx however i feel like someone at sometime mentioned that the crf actually already has these bigger valves in it? If that is the case then id go buy a new crf head from service honda for the crf for 200.00 and get the valves for it, say another 100.00, and send it out to get ported and have no down time. Is this all wrong or what? Thanks in advance to anyone that reply's. By the way, this 450 kicks ass, honda should have made this thing 10 years ago when we were cornered into buying 300ex's!

 

[86atc250r]

Intake valve size is the same on both heads --- I've heard some CRF owners change their intakes to TRX valves because of problems with the stock Ti valves.

I've not been able to get much info on the interchanging of the heads, but to add to Desert's list, I don't believe the CRF head has provisions for the temp sender or the thermostat.

From what I understand the CRF had also has larger ports, but I haven't checked that for myself....

 

[558KingR]

Welp, its not looking good on the "no down time swap" I thank you both for the reply. Mayby for 200.00 i get a new trx head and have it worked on and then swap it and sell my origanal head to someone else who wants to get work done on it and have no down time for themselves......Im not so sure after looking in the exhaust port that there is anything much to port in there. I see you can trim the guides down and do a little smoothing but not all that much to port in there it seems. Good looking head out of the factory if you ask me.