i had 22cc domes in my powerhead and had 290 jets in the carbs...runs great but now i want to put 20cc domes in and run sanoco gas..i think its 114 octane or 117...help me out please

 

so what i wanna know is do i have to put say 300main jets or 310 or to just stay the same old 290's

 

Higher octane fuel doesnt mean more power. Octane simple describes the fuels resistance to preignition. In your case 114 is too much octane for 20cc domes. You usually dont have to use race fuel until 17cc domes. You wont know if you need to change your jetting until you check your plug. You probably will have to go up, but dont guess, read your plug.

 

ok brandon...no offense but u know absolutely nothing about what u r talkin about because i went ride it after i put it together and my plugs were fine and it actually runs better with the sonoco instead of pump(i ran both gases to test)...just wanted to tell ya dont answer questions if u dont know about them.

 

have you ever read any books on two stroke tuning and performance in general? I ddidnt think so. I agree, race gas does seem to run a little better, because it is HIGH QUALITY, not high octane. This is totaly different debate that I hoped we could avoid. Octane simply describes the fuels resistance to preignition. If octane is two high for the application, you can actually LOOSE hp. If enough commpression is not pressent then guess what? The fuel resists detonation until it is not at an optimal time within the power stroke. Enough on that. My only sugestion was that you dont do a mod just so you can use race gas, the horse power doesnt come from that. The hp comes from the mod, and burning race fuel allows you to increase the state of tune in an engine(ie more compression). If you want to run 390 octane fuel then go right ahead, I just thought i would share my knowledge and save you a little money. One day when you get a little time, bring that big bad banshee over here and we can see who knows more about building high horse power engines. I doubt that you wnat to tangle with my creation.

 

ok think about this...i agree not to put a mod on the bike just to use race gas...i know that much and that it could possibly allow u to lose power...but u said i would have to go up on jets but actually the higher octane fuel the richer it will be...actually u would have to go down if anything. i didnt mean to get u pissed off...and i'm all up for that race!!!

 

I am by no means trying to keep the fight going, but here is some info that i did not include that is very relevent to my opinions. On the specific gravity scale, water is 0. Most racing gasses have a specific gravity of .740 or lower, where as pump fuel typicaly has a specific gravity of .750 or higher. This is important because it affects the mass of fuel that can pass through the jet orifice. a low density fuel has less energy potential than an equal amount of high density gas. This means that you will receive more energy from the higher density fuel, because it contains more enrgy producing hydrocarbons. This is why i advocate the use of only enough octane to stop detonation and preignition. While I may sound a bit to the finatical stage about fuel, my buisiness is drag racing and the winner and losser is sometimes decided by 1/1000 of a second. I want my motor to produce every single bit of hp it is capable of. And I never said that you would have to go up on jets, I said you wont know until you check your plug. However from my experience, race fuel does burn slightly leaner than pump fuel, but if you jetting isnt border line on pump fuel(if your in the middle of the jetting range) you probably wont need to change it at all. And by the way, my banshee currently dynos about 78+ horsepower at the rear wheels. Still up for it? Have a good one....

 

now i'm j/k when i say this but man what the hell did u do this morning read the dictionary while on the toilet or something??? but i do know what those words are...its just not all ppl who know things about quads use those words...glad to see fellow quad racers use big words and yes i am still up for the challenge even though i didnt have my nike on a dyno yet but i know the hp is somewhere around there!!