Aviation fuel in bike, good or bad?

[adventure rider]

The new to me bike has aviation fuel in it because the previous owner did not use the bike much and said that he fuel would not spoil as fast as regular gas.

[Rockjockey]

He did not lie to you it is already stabilized. I use 50/50 avgas and super unleaded in mine. Not required but it lasts longer and burns cleaner.

[4strokeridertt]

Aviation fuel is not formulated to run at sea level. It's oxygenated and has additives for high altitudes. You should not have to run anything but premium fuel. It may last longer but that is it's only benefit.

[joman2055]

there is always a debate about this and usually there are more arguments against av. fuel than for.

i have seen pics of a torn down engine that was running av. fuel and it didnt look pretty.

[helifixer]

Theres no debate. Get rid of that fuel. Use premium.

[adventure rider]

Use premium? You mean the bike won't run well on 87 octane?

[RedRider3141]

Stock form it will probaly run fine on 87 but many Honda's I've owned will tend to ping when lugging them uphills or when the engine gets hotter. Using premium is all you need to cure that. There is no reason to run anything higher than premium on a Stock XR250L.

I'll check my owners manual for the L this weekend for what Honda recommended. I think it was 87 or 89.

[creeky]

Here's some basic info on avgas.

www.osbornauto.com/racing/race2avgas.htm

[RedRider3141]

Here's some basic info on avgas.

www.osbornauto.com/racing/race2avgas.htm

After Reading that you may need this link:

http://www.thumper-racing.net/XR250R280cc.html

With the money you saved on the bike you could go for the 280 kit. (XR250Ls in my area go for as much as $2000-2300 just because of the plate, when a similar year XR250R goes for $1200.)

[HawkGT]

Here's some facts about 100LL (practically the only aviation gasoline available anymore) from ChevronTexico: Aviation Fuel Technical Review PDF. Chapter 7-11 are about aviation gasoline. Here's another one about pump gasoline to help put things into context: Motor Fuels Technical Review PDF.

Most of the characteristics of 100LL that could negatively affect performance in our motorcycle engines are just as bad OR WORSE for pump gas. I'd suggest paying particular attention to the distillation curves and distillation specifications for various fuels. Take a look at the figures for 100LL, pump gas, and then look at some race gas. VP's C12 might be a good all-around example to compare with (you can get the spec sheets from VP's website).

Beyond those comments, I'm tempted to just say what I think--but then I'd just be another guy on the Internet with an opinion about gasoline. I've been burned by that guy too many times! Plus, it would take me forever to outline everything I think is important. My bottom line is I think most folks will be better served by putting in the time to learn what the various fuel specifications are and what they actually mean for you and your engine.

Remember, whichever fuel you choose to run: confirm the jetting everytime you switch fuels! Many folks are led astray by their own fuel experiments by not rejetting appropriately for each fuel....

Good luck!