I have two questions: #1) How big of a standard bore, high comp piston can I go before I must use the race gas? #2) Is there any benifit in using the race gas if your machine doesnt have high comp piston, porting, etc.? Thanks in advance for any info.

 

That is a hard question to answer. Detonation depends on more than bore and compression.
To take a stab at this. With premium pump gas around 11.5 or 12 to 1 is about the limit with an aluminum head and water cooled.

To answer your second question is easy. No it won't.

 

That is a hard question to answer. Detonation depends on more than bore and compression.
To take a stab at this. With premium pump gas around 11.5 or 12 to 1 is about the limit with an aluminum head and water cooled.

To answer your second question is easy. No it won't.

 

12 octane you can run 92 octane i will put money on it because honda trx 450 has 12 compression in their engine and they say 02 mininum. Honda would not sell a bike from the factory that requires race gas anything over that i would run 100 octane thats what i run in my yfz 450 which is what is recomended from yamaha

 

i meant 12 compression and 92 octane lol sorry about the typo guys

 

Yeah but the Honda is also water-cooled and specially designed for that high compression with that fuel, whereas most other quad engines are not. Most piston manufacturers will say racing fuel is required on anything 12:1 and higher.

 

yes you might be right however my yfz is also water cooled and needs only 100 for a 13.2 piston yes you would be safer with higher octane however i think if its not available 92 would work fine with 12 compression yamaha comes out with 11.6 stock and recommends 91 or higher my buddy has a 12 compression in his 440 kit in his honda 400 and hasn't had a problem for years

 

there r much more things than just the comp rate that will make if u have to run race gas or not. things like cam design, piston and crank lengh. to give us a better idea of what u can and cannot do what kind of bike r u ridding?

 

ok now by seeing your other post and see u have a raptor 700 which is my bag. a good rule of thumb on the raptor 700 as far as how high of a comp rate u can run and get away from pump gas is 11.5:1 comp and under u can run good pump. or if u are at very high elevation a little more. the reason bikes like 450s can run pump with high comp rate pistons is because they have almost no stroke unlike a raptor. now running race gas with lower comp is just robbing power, you only want to run as much oct as u have to have with making your motor explode. btw the head porting u have doesnt mean anything on what octane u have to run. i am at over 14:1 comp (real comp not guessed) with my raptor and run 110 oct.

 

i agree with the post above i was takin into consideration that this post was a 450 a raptor is a whole different story it makes different power than the 450s it makes its power in the longer stroke which does not require as much octane to reach the equalibrium of the motor