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View Full Version : Looking for coolhead advice.. What dome to use?? Too many choices



mmartin
12-21-2010, 10:14 PM
I just purchased a JP coolhead along with 3 different domes. An 18cc,19cc and a 23cc dome. Im not sure which one to start with?? Does anyone know what the advantages or disadvantages are between the 3 different sizes?? If it will help with advice here is a list of the my mods, stock jug bored supposedly.120 over according to previous owner. 39mm pwk carb, v-force reeds and cage, ESR airbox eliminator,Fmf fatty pipe and silencer, oversized intake between carb and reeds, ESR adjustable timing advancer, porter intake, polished and ported exhaust. That's all that I can think of off the top of my head as far as the engine goes. It's been a really fun build and learning as I go. Does anyone have any experience with the different dome sizes?? Any help would be appreciated.:naughty::naughty:

KASEY
12-21-2010, 11:05 PM
THE DOME SIZES CONTROL THE AMOUNT OF COMPRESSION, i am pretty sure the 23cc dome is a pump gas dome.. but you will have to put one on and do a compression test to see how high it is .. anything over 180 should have at least 50% mix of racegas..

pickleweasel_00
12-22-2010, 12:01 AM
at what psi do you need full race gas?

cr480r
12-22-2010, 12:09 AM
if you have a large overbore or a big bore kit, be sure the dome is matched for the bore diameter.

mmartin
12-22-2010, 12:55 AM
If I go ahead and use the 18 or 19cc dome would there be anything to worry about as far as the integrity of my rod or causing something to seze up? I'm guessing that the race fuel is to avoid premature detonation due to the added fiction of the higher compression? Will it be ok to keep the timing advanced with the race fuel domes? This is all a learning experience for me so thanks for all of you guys help. I'm gonna try and get some pics posted of my build on here real soon.