I have 00 400ex with a few mods, I have ran 93 octane from day 1. The other day i went riding, & used most of my tank, so i filled it back up with my buddys racing fuel. I noticed a big difference in the way the bike ran. I know your not supposed to mix racing fuel with regular gas. I would like to run straight racing fuel now. I have heard once you run a certain gas (either racing or 93) you must stick to it. Is this true? Will it hurt any thing (besides my wallet) running racing fuel now??

 

the only thing that i have herd about race fuel is that if it is leaded it can carbon up the valves. I have run it in my bikes and my toyota with no trouble..but if it doesnt ping with 93 you probley dont need it.
Joe

 

does racing fuel increase speed and performance and where can i get it

00' 400ex dg race nerf bars w/ pegs/ mod. air bos. rear shedder tires

 

the only thing race fuel does is:
1. burn cooler
2. more controled burn (no pinging)
3. slower burn, not faster as many people think-it is less explosive!

 

the only thing race fuel does is:
1. burn cooler
2. more controled burn (no pinging)
3. slower burn, not faster as many people think-it is less explosive!
the only time it is needed is when run in a built engine or a race engine (the 400EX is almost a race engine stock,but will run just fine on pump fuel unless hopped up with a piston/cam then race fuel is a must
Joe (sorry for the doubble post,i hit enter to drop down a line)

 

If your engine is not spark knocking [pinging] higher octane fuel is a big waste of money.Octane has nothing to do with an engines ability to perform at a higher[faster] level.===BILL

OO Xplorer 400cc 4x4
If you want to come in second ''FOLLOW ME''

 

I heard it will make the 400ex harder to start in colder weather. that's want they said in dirt wheels later

 

Racing fuel will actually give you less performance in a low compression engine, or in other words anything designed to run on pump gas. The only reason racers use high octane fuel, is because the engines they run usually have very high compression. If they didn't run high octain, their engines would suffer from severe detonation. Which is when the fuel starts to burn, from the heat a high compression engine generates, well before the piston reaches top dead center. Thats the ping you here, the fuel starting to burn and creating pressure in the cylinder, while the piston is still traveling up. Not good unless its only a few degrees advanced.

 

I would have to assume that none of you have ever used racing fuel before. Dick Gazan(?) built a small block chevy to use as a dyno engine ( one to try new parts on), It was built with 9:1 compression and was to be for pump gas. Of the things he tried, he used SONOCO 104 octane racing fuel and picked up 11hp. He noted that this was without rejetting for the race fuel, and that a bigger gain would be noticed if rejetted.
As far as burning cooler, that is totally false. Racing gas burns alot faster, and alot hotter. It is alot more flamable than regular gas. Just like gas is more flamable than diesel fuel. The best thing to do is try it and if ya like it, use it. It will make a big difference.

 

asfastasu, I would guess you know nothing about what you speak. I would also guess that the person with the 9 to 1 motor advanced the timing to gain hp, which would also require high octain fuel to prevent detonation.