Installed a cool head

[FMS50]

I just got another banshee and I want to put a cool head on it. The bike has a stage 3 port job, T5's and thats about it. I bought a cool head with 18cc domes and im wondering if I will need to rejet the carbs after the head is installed. I have a cool head on my other banshee and didnt rejet it but I only went to a 21cc dome not a 18cc dome. I am asuming I wont need to rejet but i wanted to get some opinions first.

[Trick2stroke]

Yes, you will. You will most likely have to run race fuel also depending on how much material was taken from that "stage 3" port.

[Bansh-eman]

the porting wont effect the compression very much few lbs max...and if anything porting will lower your compression... with 18cc domes your at least looking at 50/50 depending on elevation...

Edited February 27, 2007 by Bansh-eman

[Ducman]

Being a little rich will help stave off detonation so you may want to go up a main size to be safe, but if the engine was already jetted perfectly or a hair on the rich side then no jetting changes will be necessary for increased compression. You will need to use race fuel with 18cc domes though, id go straight 110. Porting will lower static compression if the exhaust port is raised but this can also increase dynamic compression, so dont go off of charts saying 160 psi is OK for pump gas on a ported motor especially for a somewhat top endy port. A trail port maybe.