Fuel question.....

[theJeStEr1340]

QUOTE

Originally posted by BigJosh
You can take this advise or not but I can send pics of some melted pistons. I would run 93 octane and use a fuel booster but only use about a 1/4 of it per tank.  This has happened to both a 450 piston the stock 432 piston. And we didnt realy see any diffrant power when we ran 110 mixed with 93. But its your motor.............:mad:  Just wouldnt want to see this face...

I would like to see pics... I don't understand how race gas caused this, higher octane burns cooler. And JBBSpeed has been running a mix of gas at around 100 octane for years, since he got is speed new in 02 and hasn't had any problems, and he has no updates at all or anything.

[Honeycutt]

I have been running VP ultimate II in my speed,with about 20 hours on it, mostly drag racing,no problems yet.

[61austin]

QUOTE

Originally posted by BigJosh
You can take this advise or not but I can send pics of some melted pistons. I would run 93 octane and use a fuel booster but only use about a 1/4 of it per tank.  This has happened to both a 450 piston the stock 432 piston. And we didnt realy see any diffrant power when we ran 110 mixed with 93. But its your motor.............:mad:  Just wouldnt want to see this face...

Was the race fuel that you used oxygenated? If it was you have to jet up for it or you will run lean.

[BigJosh]

Well here is what leads me to belive it was fuel related. The motor probly had about 25 or 30 hours on it. 450 kit all updates. The thing ran great took it flat track racing put 110 VP racing gas mixed with 93. No idea if it is oxygented or not. Got it from a local polaris dealer who dosent sell much of it. He said it was kinda old but seemed ok. So maybe it was spolied gas that did it. But all I know is we put some inthe weed eater and poof it dosent run either so I just thinking its a fuel issue.........Any thoughts

[Happyboy]

It could be what ever was in that fuel. But, race gas will not melt a piston and rings by itself. You can do that under a lean condition.

Now, maybe something else was in that fuel.

[Psychosis]

I'd say it's bad fuel or something. If you put it in a weed eater to the same result then there's the source of the problem. I've been using 110/93 combo since May and done nothing but MX w/out a single problem. The piston had about 30hrs or so on it before it was rebuilt as well but had ran just 93 before. So over 100hrs easily on the stock piston and most on a race gas mixure. I forget which it was but it's a VP gas that I use.

[toothandnail]

I don't know about the weed eater but read the "dales at the flat track" thread thats why they burned the pistons .I dout the fuel had anything to do with it unless it was oxygenated.

[61austin]

QUOTE

Originally posted by Happyboy
It could be what ever was in that fuel.  But, race gas will not melt a piston and rings by itself.  You can do that under a lean condition.

Now, maybe something else was in that fuel.

Yep, a little nitro propane would definitely produce those results if it wasn't jetted for it. That stuff is a little weird also in that it doesn't create all the usual symptoms of a lean condition, we always used to jet for it at night that way you could judge how much adjustment to make by how much the pipe was glowing.