Race Gas?

Court Jester said:

done 5 dyno's on the 636. three with vp race fuel, two without. 3hp increase with the vp.

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Thats because all VP "race" fuel is oxygenated. And if you only saw 3hp, then something is wrong. U4.2 will give a stock bike around 5-6hp without a tune. 7-8hp with a tune.


If you run U4.2, your bike should pick up around 5hp. If its just 110 octane, non-oxygenated fuel, then its a waste of money.

Court Jester said:

not trying to argue though. just making sure that the dude gets the right info. higher octane fuel will burn cleaner, clean injectors and stuff, and add hp. that's all.
i'll try to get the dynos posted sunday.

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Higher octane fuel by itself will not add hp. burning cleaner and cleaning injectors depends on the detergent additives added to the fuel, not the octane. The only thing octane does is increase the resistance to knock, and allow you to run more timing in the motor or a higher compression ratio before you get detonation.

I'm not doubting that running VP gas gave you a few more horses, I totally believe that. What I don't agree with is that octane gave you those horses. Most VP gas used is oxygenated, which is where the power comes from. Octane and power have almost nothing directly in common with each other.

VP U4.2 will give a noticeable difference in power and is the most widely used for motors that aren't heavily modified and don't run ridiculous compression ratios. Most places charge around $10-$14/gal for it. If you use this, make sure that you drain the tank and run the bike dry if its going to sit for a while(more than 2 or 3 days). If you ride the bike every day, then you should be fine burning down to like a 1/4 tank and just putting pump gas back in and running it.