Av gas

[Mgt]

Is it okay to run Avgas in a 4-stroke

[Mike Talbott]

trying to find non ethonal fuel in so cal,

[Mike Talbott]

i found plenty of debates on av gas sorry for the repeated question.just looking for gas without the ethonal

[Jim Dettman]

Well you certainly don't want the ethanol if you can avoid it, but buying AV gas is not a good idea.  While there is no catalytic converter to damage, AV gas has a high lead content.  AV gas is meant for large bore long stroke engines running at low rpms, which is not your CRF.

You'd be better off to buy regular 93 octane gas and treat it with a stabilizer specifically made for ethanol fuel and keep you tank full as much as possible.  I'm fortunate to have non-ethanol fuel here, so I don't have first hand experience with this, but that's the route most take.

The other option would be to buy racing fuel, but again I think that's overkill.  You don't need 117 octane and it's not cheap; approx $80 for 5 gallons.

Jim.

[TDW]

10 hours ago, Mgt said:

Is it okay to run Avgas in a 4-stroke

Yeah av gas will work, probably best to mix or blend it with pump gas. I would start with a 50/50 mix and see how you like it.

Not sure why or what you want to use it for, to get rid of the ethanol?

Using 100 LL av gas was more common back when the crf 250 and 450 first came out in an attempt to extend the life of the intake valves. Best thing is that now that really isnt an issue anymore.

[tomerb]

At a dyno tuning session with my 14-1 compression Yamaha Raptor 843 I started with 110 octane race fuel. It made 93.45 HP. We drained the tank and filled it with AV gas.

We did some more runs and came up with the same HP and torque on AV gas as we did with 110 octane race fuel, all at a low RPM of 9200

I have run nothing but AV gas in three 2012s with nothing but great results. With no plugged up carb jets and never a tight valve on any of them.

Also no detonation when lugging in the wrong gear. 

[Piney Woods]

I never have but have friends who have used av gas exclusively for 40 years with zero issues. Another alternative to ethanol blends is gas from a Marina, most is usually non-e.

[TDW]

When I was using av gas I dont remember having any issues with it but remember the exhaust had a different smell to it because of the lead content, and having to go to the local air field to get it which wasnt a problem. I dont know how much it costs now but back then it was alittle more than the 93 octane pump gas but not alot, and alot cheaper than race gas. I dont remember ever trying any additives.

[Jim Dettman]

The issue is though is that av gas has a lot of lead in it, which today's engine designs don't take into account.   So what may have worked in the past doesn't mean that it will work today (look at the way you used to break-in motors vs now).  Lead leaves a lot of deposits behind on valves and pistons, which is not great for a small bore, high rpm engine.

If your going to try it, use AV 100LL (low lead) at least instead of AV 100 if you can get it.

The biggest problem with ethanol based fuels is letting them sit.   Even if treated with a stabilizer, letting it sit longer than a month can give you problems.    If you bike doesn't sit for long periods, then it won't be an issue, and I would lean towards using that rather than AV gas.

Jim.

[96motorhead]

Yes it is okay to run in a 4 stroke.  I switched to av gas in my crf450r last year after talking with Del West.  Del West told me to run it because it contains lead which is a lubricant.  I don't have any problems with deposits on anything either.  Also I richened my needle 1 clip when I switched because I had some popping during deceleration.  So far I have experienced no bad effects after switching to av gas.

[MaynardZed]

FWIW, we run AV gas exclusively in our Formula Ford race cars. 1.6L 4 stroke carburetor engines that are run hard near the 7500 rpm redline all the time. It's a little dry, so we put a pinch of Marvel Mystery Oil in it. 

[TX-SANDMAN]

Av gas is awesome .... when I use it my bike runs better.  Any thing in aviation industry is usually made to much higher standard and much more regulation ..... hence more consistent.