Anyone use race gas?

A 2 stroke riding buddie of mine started using race gas in his son's bike. He has been raving about how much of a difference it has made in throttle response and even power. I guess he is getting better mileage as well.

This has got me thinking about trying some in my Thumper. Have you ever used race fuel in your bike? I am thinking about trying the VP ultimate 4 I believe it's called.

Any thought on this?

Funny you should bring that up. Spent the better part of an hour yesterday reading old posts on racing gas. Looks like people think it's either the greatest thing invented or the a huge waste of money. I haven't run into any detonation problems yet, so I'm sticking to pump gas. My bike has way more horsepower than I need anyway.

I would be careful with using Ultimate 4 as it's leaded. Running it once in a while wouldn't hurt, but the lead does tend to leave deposits if you use it all the time (this is based upon my experience with putting unleaded valve seats in a small block Chevy racing engine, and hopefully is applicable here).


I was having some backfire problems with the pump gas 91 octane on deceleration down hills and such. I switch to mix of race gas and pump gas to up the octane to around 100 and the backfires went away. The book says to use 96 octane.

My buddy just started using V U4 in his 01 426 and loves it. Says he notices more throttle response. But for $10 a gallon, forget about it.

Some 76 stations sell 100 octane (unleaded) for $4.55 a gallon. Dosen't have the smell of the VP which means you can keep it in the tank. I mixed it 50/50 and still notice a little extra punch with a lot less cost.

If you can get it, why not. Your bike will run cooler and cleaner.

The pops you get during engine braking indicate a slight leaness in the pilot/idle circuit. The way I understand it, the slower burning race gas will cause the engine to run richer, hence removing the lean condition and removing the pops.


91 PON (pump octane number; average of Research and Motor octane) is reccomended. Our Esso here used to sell 92 PON but they now only have 91 PON like the others. My 426 had a slight ping, especially near the beginning of the power band, which worsened when PON was dropped to 91. Starting this spring, I will have a 45 gallon drum filled with 1/3 "100 LL" (100 PON low lead) aviation gas, with 2/3 "91 PON" unleaded which will give me "94 PON"! This will rid of the destructive and anti-efficient ping (pre-ignition). Performance, grunt, response and smootheness of operation should improve also.

Higher octane fuel does burn slower and more efficiently in a high compression engine and I may have to switch from a 175 MFJ to a 172, and a 170 in the summer heat.

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