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Is AvGas LL110 or LL100 bad for my bike

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I am rebuilding my yz250 and when I am done it will have 11.7:1 compression from a new wiseco piston and over bore and it will have advanced timing, fmf gnarly pipe, new reeds and new jetting. It will most likely need a mix of race gas and 93 which is the best I can get at the pump. Will the AvGas (airplane fuel) mixed with pump gas and premix ruin my bike in the forseeable future? I have heard that it drys out the main seals and gives bad throttle resoponse but is that true and does it change anything if it is 1/3 LL110 and 2/3 gas + oil? This gets me leaded 99 octane.

Edited by tothemax

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AVgas won't hurt anything. Worst it will do is leave a little whitish yellow lead deposit. I occasionally use it in my Rotax 582 2 stroke ultralight engine when it's not convenient to fill with car gas.

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I used it in my yz144 with high compression with no problems. I know of lots of people who run it in snowmobiles too.

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been running it for years no problem.plus it has an altitude stabilizer that helps engines run clean at high altitudes.cant have an air plane running like crap at 100.000 ft.

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been running it for years no problem.plus it has an altitude stabilizer that helps engines run clean at high altitudes.cant have an air plane running like crap at 100.000 ft.

It doesn't have an "altitude stabilizer". Airplane engines are leaned manually by the pilot so that they don't run "like crap" up there.

Please read these threads for this recurring question:

https://thumpertalk.com/forum/showthread.php?t=906250

https://thumpertalk.com/forum/showthread.php?t=944020&highlight=aviation+gas

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Thanks, sounds like I'm good to go. And to the guy who asked were I get it, I know the people who own the local airport in my hick town but I think you can drive up to the pump. Just make sure the airport staff know whats going on.

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I'm with them. Avation gas is dry but you will be fine because its a 2 stroke and you have to add oil to your fuel anyways. 👍

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Since 9/11 a lot of small airports have put up chain link fences to keep people out so you might not be able to drive up to the pump. You may have to carry the can to the pump. Some airports have pump it yourself systems that take credit cards and some only sell gas directly from the tanker truck. Just ask at the airport office.

Thanks, sounds like I'm good to go. And to the guy who asked were I get it, I know the people who own the local airport in my hick town but I think you can drive up to the pump. Just make sure the airport staff know whats going on.

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FYI it is illegal for airports to sell you avgas. You may be able to get it but it's something to think about.

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FYI it is illegal for airports to sell you avgas. You may be able to get it but it's something to think about.

thats why they sell it to you for your ultralight 👍

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It is illegal but happens all of the time. Just don't give them a reason to say no. It's for your plane on your private strip, right?

Avgas is very stable and doesn't break down fast like pump gas, and a high compression engine with about 30% avgas usually runs great.

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FYI it is illegal for airports to sell you avgas. You may be able to get it but it's something to think about.

It is legal for offroad use only. BUT, You need to mix it with non ethanol 93 oct or race gas. Running it straight usually causes a hesitation at low rpm and throttle response. It is designed to run at a constant RPM. There is not a 110LL AvGas. AvGas blue is 100/110LL . Different octane rating at different altitudes. Also the LL means low lead but it has much more lead than MoGas or Auto / Pump gas ever had. It just means low lead for AvGas. AvGas is also designed for low RPM operation. Most airplane engines run under 3000 RPM. AvGas is not Race Gas. But it doesn't have ethanol.

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It is legal for offroad use only. BUT, You need to mix it with non ethanol 93 oct or race gas. Running it straight usually causes a hesitation at low rpm and throttle response. It is designed to run at a constant RPM. There is not a 110LL AvGas. AvGas blue is 100/110LL . Different octane rating at different altitudes. Also the LL means low lead but it has much more lead than MoGas or Auto / Pump gas ever had. It just means low lead for AvGas. AvGas is also designed for low RPM operation. Most airplane engines run under 3000 RPM. AvGas is not Race Gas. But it doesn't have ethanol.

ETHANOL key word.👍

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I heard it is illegal because you don't pay the taxes on it that you pay at the auto gas station, so ok for off-road use as others have mentioned. My local airport will sell it to you but they will not pump it and it must be put in a container for off site use. Also their pumps require you to enter a tail number before the pump will switch on. Guy said he wished they could put a pump outside the gate cause lots of people want for their race cars, bikes, etc. I used to run it mixed with 93 in my 400ex with no problems.

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There are a lot of wife's tales about 100LL. I've been running straight 100LL in all my 2-strokes for 30 years. Contrary to popular belief, straight 100LL gives excellent throttle response as long as the jetting is somewhat close. Pump gas and 100LL jet out close to the same. The bottom line is 100LL is an excellent fuel for 2-stroke race bikes.

Here is a good search engine for the best avgas prices in your area. Just plug in your zip code. http://www.airnav.com/fuel/local.html

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I get my AVGAS from the local airport and I'm almost positive they charged me tax. It ends up being something like 4.25 per gallon, give or take. I do run it mixed with 93 pump gas. About 50/50...maybe a little heavier with the AVGAS. Like CamP said, the jetting is key.

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I get my AVGAS from the local airport and I'm almost positive they charged me tax. It ends up being something like 4.25 per gallon, give or take. I do run it mixed with 93 pump gas. About 50/50...maybe a little heavier with the AVGAS. Like CamP said, the jetting is key.

I'd say there is still sales tax but the state and fed. road/highway taxes aren't there from what I read. Unfortunately I can't remember where I read it so it could be wrong.

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Strange that the pump would require an N (tail) number since ultralights do not have N numbers.

I heard it is illegal because you don't pay the taxes on it that you pay at the auto gas station, so ok for off-road use as others have mentioned. My local airport will sell it to you but they will not pump it and it must be put in a container for off site use. Also their pumps require you to enter a tail number before the pump will switch on. Guy said he wished they could put a pump outside the gate cause lots of people want for their race cars, bikes, etc. I used to run it mixed with 93 in my 400ex with no problems.

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* you are correct about it being illegal

How ever it is only illegal on road used cars..

#1 is the lack of taxes used in maintance of highways and streets.

#2 the lead level will destroy catalic converters and any car that has one can not legal use it even if the gas is only used when the car is racing off road.. Because it still destroys the cat.. I would not try and prove to the epa or DOT that you had straight pipes when running it or you only use the car racing..If they car is not titled as a road capable car and race only then you're fine. They will not take your word for it and you're just going to get fined or even slapped with a misdemernor or felony ect..

If you are using it for non highway use in a non public road useable vehicle then you're good to go..

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