661 Oil Test 32:1 vs 40:1 vs 50:1 ?

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Trx250r180

Trx250r180

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I spoke with a customer of mine that runs Stihl Ultra @ 40:1 and the crown of his pistons are completely clean. The difference? He runs 100LL fuel. This would suggest that the fuel has as much to do with it as the oil. Food for thought :)

Is it because the race gas is not burning as hot ?
 
bwalker
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One other thing about avgas is that it's a very clean fuel, lead withstanding. It.will not form.gum or varnish for a very long time. Like 5 years or more. ASPEN fuel that is marketed in Europe is a high alkylate fuel similar to avgas but minus the lead and also it has a more appropriate distillation curve.
Pump fuels are so.low in quality now days that they end up forming much of the deposits you see in a two cycle. If you use of a good race fuel like VP C12 or MR2, which both have distillation curves compatible with a two cycle you will have a pretty clean motor provided you use a decent quality oil.
 
Ron660

Ron660

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****
I spoke with a customer of mine that runs Stihl Ultra @ 40:1 and the crown of his pistons are completely clean. The difference? He runs 100LL fuel. This would suggest that the fuel has as much to do with it as the oil. Food for thought :)
I use Sunoco 110 with my Motul 800 off-road mixed at 32:1. My compression is over 210psi. Works for me.
 
Andyshine77
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I spoke with a customer of mine that runs Stihl Ultra @ 40:1 and the crown of his pistons are completely clean. The difference? He runs 100LL fuel. This would suggest that the fuel has as much to do with it as the oil. Food for thought :)
That's what I said about a 1,000 posts ago. Like I said, no new information in this thread!!![emoji8]
 

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