2/2 many banshees Posted June 1, 2008 Report Posted June 1, 2008 looking for the right size domes to use in my cool head the bike has some small mods fattys,34mm pj. carbs., +4 timing, mx port, lighten fly wheel,and rad valve (thats all I can think of right now) let my know what you think Quote
new2_2stroke Posted June 1, 2008 Report Posted June 1, 2008 Allright guys dont be to hard on me if i am wrong. But those that will be able to answer your question will probably ask the following. Do you want to run pump gas or racing gas. Quote
2/2 many banshees Posted June 1, 2008 Author Report Posted June 1, 2008 Allright guys dont be to hard on me if i am wrong. But those that will be able to answer your question will probably ask the following. Do you want to run pump gas or racing gas. I want it to run hard, strong and right if that to much? Quote
Bansh-eman Posted June 1, 2008 Report Posted June 1, 2008 I want it to run hard, strong and right if that to much? This doesnt help any. You can run hard and strong on every type of gas. We need to know if your willing to spend the 6 or 7 bucks a gallo on race gas or not. Plus list all your current mods, evelation and temps. Quote
Snopczynski Posted June 1, 2008 Report Posted June 1, 2008 Gonna need to know the exhaust port height, what fuel you want to run, and your elevation. If you dont know the exhaust height, then we need to know your current compression and which domes you have or if its a milled stock head. Quote
2/2 many banshees Posted June 1, 2008 Author Report Posted June 1, 2008 ok I'll say 93 oct. the exhaust height I don't known firt time putting a cool head on looking for a place to start I dont see the point to by 4 sizes of dome and wasting money when we have so many guys on here that I'm sure have gone dowm this rode Quote
rubberneck Posted June 1, 2008 Report Posted June 1, 2008 If at sea level, with +4 timing and want to run pump gas, 21 cc domes Quote
jamebo Posted June 1, 2008 Report Posted June 1, 2008 Yeah I'm at sea level and run the 21cc's. I run pump gas. With gas prices the way they are I'm gonna keep them too, because I sure can't afford race fuel! lol Quote
2/2 many banshees Posted June 1, 2008 Author Report Posted June 1, 2008 thanks for the input guys. if I went with 20cc it would need race gas? or if I went with 22cc I'd have less power? am I looking at this the right way Quote
rubberneck Posted June 1, 2008 Report Posted June 1, 2008 Added compression will tend to give you some pop off the bottom. I have seen guys say they run 20s and pump gas. You may be able to. I just dont like to push it, as detonation can tear things up fast. Quote
jamebo Posted June 1, 2008 Report Posted June 1, 2008 thanks for the input guys. if I went with 20cc it would need race gas? or if I went with 22cc I'd have less power? am I looking at this the right way What is your elevation? At sea level 21's are probably as low as you want to go on pump gas. You might could get by with 20's, but I wouldn't chance it. Just depends on how much compression youv'e got. Anything over 160 and I believe you're looking at a mix of fuel. 22 domes would be about like stock. Quote
2/2 many banshees Posted June 1, 2008 Author Report Posted June 1, 2008 yes at sea level.like it is all so bored 80 over does the matter? Quote
Snopczynski Posted June 1, 2008 Report Posted June 1, 2008 No guy on here has your exact port job, so to make the proper recommendation to get you right on the edge between race gas and super unleaded we are going to need to know exhaust port height or current compression with which head your currently running. So glad I had to repeat myself. My bike runs 18cc domes in it at 185 psi compression because of the exhaust port height. Most bikes with those domes would be running at around 195-200 psi with 18cc domes. SO, thats why its important to know, othewrwise you could end up buying at least 2 sets of domes to get where you want to be. Quote
ITALIABANSHEE Posted June 3, 2008 Report Posted June 3, 2008 I currenlty use race gas on my stock shee. Am I going to blow my sheeet up? Also why does the size of the domes matter if using reg gas and VP? thx. Quote
tgbanshee Posted June 4, 2008 Report Posted June 4, 2008 (edited) I currenlty use race gas on my stock shee. Am I going to blow my sheeet up? Also why does the size of the domes matter if using reg gas and VP? thx. You aren't going to blow up your stock shee by using race gas, but you are wasting money. There is no need to pop for race gas when your motor doesn't need it. You don't get extra horsepower from having higher octane, octane is added to fuel to make it resist burning, it does not make it burn hotter. In high compression or advanced timing motors the fuel starts burning before it should (detonation, preignition, etc), which can damage the piston, connecting rods, crank, etc so high octane fuel needs to be used to prevent that. Changing dome size increases compression if you go lower in cc's and decreases compression if you go higher in cc's so that can potentially effect what type of gas you need to run. Elevation will also effect the compression as the higher you go up in elevation, the less atmospheric pressure there is, hence less air will make it into your motor and vice-versa. These things all factor in and you really need use a compression tester and do a compression test if you have a modified motor to find out where you are at and make a decision regarding which fuel to run. Edited June 4, 2008 by tgbanshee Quote
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