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Discussion Starter #1
Just wondered how a bike would run on 100LL AVGAS ....100 octane (Low Lead) Aviation gasoline as opposed to the unleaded 94 octane we get at the pumps?

Better ? worse? not a lot of difference?

I ca get probably a gallon or so every few days from aircraft fuel daily tank fuel checks.

Any one run 100% AVGAS? I tend to stick a few litres in to the tank of the car when ever I have spare can full..just wondered about running the bike on it full time?
 

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Low lead probably would not hurt anything, but lead is bad for the stellite (sp?) coating used on valves. If your valves are stainless or titanium then there probably won't be any issue.

The main reason I would not run the av gas in my racing engines (bikes and quads) was simply because it's not regulated well enough to know you're getting the same octane each time. It can vary as much as 7 points, from what I was told years ago.

Probably no help, just some ramblings.
 

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Discussion Starter #3 (Edited)
OK< thanks

I guess the SP coating is designed as lead replacement ..for use with unleaded fuel?

Just got standard HD valves.

Surprised it is not regulated well enough..everything else in aviation is so tightly regulated, but seeing the engines they run in .. I guess it does not matter that much
 

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Biggest thing with avfuel is resistance to vapor lock and ability to sit long periods of time without degradation. I doubt the 100LL will hurt, especially if you mix it with auto gas. My old Cessna would eat premium auto fuel before gasoline became contaminated with ethanol.

09DG is right, exhaust valve/seats are designed to like either leaded or unleaded fuel. Your scoot may be fine, but I have heard of guys burning valves with avfuel, maybe they were using the old 100/130 leaded fuel.
 

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AvGas is not low lead. The low lead is as opposed to hi lead Avgas. It has more lead than 110 race fuel. So it will rapidly poison exhaust sensors and converters. It also requires a different mix/jetting. And has some other issues too.

AvGas is short for Aviation Gasoline. AvGas is of interest to motoring enthusiasts because of its availability, octane rating and low price compared to commercial race fuels. AvGas might seem an obvious choice but closer study raises some doubt.

AvGas LL100 stands for "Low Lead 100 Octane". TEL (Tetra-ethyl-lead) is added to raise the octane. When used in a motor vehicle this fuel will leave a lot of lead deposits in the motor. 100LL has a high lead content (0.5 grams per litre), even higher than leaded race fuels. The deposits left when TEL(lead) is burned are corrosive and damaging to valves, valve guides, valve seats and cylinder heads. Lead deposits will also block oxygen(lambda) sensors and catalytic converters and foul spark plugs even after only a short use. Also, 100LL has a chemical package added to make it perform at high altitude, and that isn't the best thing for motor vehicle performance here on the ground.

AvGas is blended for large-bore, long-stroke, low RPM engines which run at high altitude. While AvGas' higher octane is useful, smaller-bore, shorter-stroke, high RPM engines will perform better on racing fuel or high quality octane boosters. AvGas has lower volatility so when used in proportions higher than about 40%, part-throttle drivability and cold starts may be compromised. AvGas has a lower specific gravity so it will require a change in air-fuel ratio calibration for the engine to perform at its best. LL100 is blended with a high percentage of aromatics causing reduced throttle response which is not an issue with an aircraft engine but certainly an issue in a high-performance automotive engine. These high levels of aromatics will also damage rubber components in automotive fuel systems such as fuel lines, fuel pump seals and injector washers.

The sale and use of AvGas is heavily-regulated. Most aircraft fuel dealers refuse to put AvGas into anything other than an aircraft fuel tank. There is a legal grey area that has some vendors willing to dispense AvGas into "approved" containers if they believe the end use of that AvGas is fueling an aircraft engine. This loop-hole is how some may obtain AvGas for automotive use. Because AvGas has no taxes and duties on it, use on public roads is illegal and if found could result in your vehicle being impounded.
AvGas Tank
The Bottom Line:

Avgas may be suitable for some race cars that don't have catalytic convertors or oxygen sensors and are rebuilt often enough that the TEL(lead) build-up is not an issue. For other applications use an unleaded race fuel or a good quality octane booster.
 

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AvGas is not low lead. The low lead is as opposed to hi lead Avgas. It has more lead than 110 race fuel. So it will rapidly poison exhaust sensors and converters. It also requires a different mix/jetting. And has some other issues too.
So if he has an old bike, designed to run on leaded fuel he would be ok?
 

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So if he has an old bike, designed to run on leaded fuel he would be ok?
Not really. Motor vehicle fuel never had as much lead as 100LL. And was never blended that same way.

In a race motor, avgas burns too slow. Might work OK in an old panhead, but would not be as good as using leaded automotive fuel.

It's also a little hard to get 100LL thats not pumped into an aircraft. Many airports won't pump it into a jug unless they already know you.
 

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On top of everything mentioned, your stock compression can't take advantage of the higher octane. Now, I used to run a 13:1 street strip bike around town and kept a 55 gallon drum of VP C12 in my house garage. Finish it, the VP guy would switch it out and drop off another one.
Had my own gas station with pump for me to pump right into my bike and go, but could only go around town as far as my tank would take me and get me home.
For your situation, No upside, too much downside.
Forget it. Stay at your local pump.
 

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Discussion Starter #9
Hell, never knew the true meaning of Low Lead before!

The plan to use it was not for a performance gain, and it was not being pumped from the fuel truck in to cans ..I was just making use of 'waste' fuel from the daily aircraft fuel drain checks.

I was merely thinking of it as a cost saving option..but if it eventually trashed the valves, then I'll not bother. It can continue to go in the old farm 2-stroke chainsaw though.

Cheers for the info guys.
 

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I've used Avgas in my evo's but had mixed it with regular fuel. Couldn't really notice a difference. Have a hard time noticing a difference when using higher Octane then 87..
 

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I've used Avgas in my evo's but had mixed it with regular fuel. Couldn't really notice a difference. Have a hard time noticing a difference when using higher Octane then 87..
What year bike that 87?
 

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My 98 heritage has always run good on 87. But I occasionally treat it to a bit more octane now and then. Never noticed any change in my MPG either.
 

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My 98 heritage has always run good on 87. But I occasionally treat it to a bit more octane now and then. Never noticed any change in my MPG either.
Mine run good on regular if it's cool. Hot weather they need premium.
 

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I run that stuff a lot and as often as I can (with a lil help friend who has a plane and pump) next door.
 

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This 100LL thing could be huge if marketed right; right up there with those drop in the tank catalyst things, zMAX and plug indexing on stock motors.
heh heh,, don't forget pully sync and fan belt porting...
 

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Thermodyne is correct - Av-gas is formulated for altitude and steady RPM operation, much longer flame speed - not good for valves; w/o the proper valve (cam) timing - motor does not reap the full benfit of av-gas (ie. burnt exhaust valves). Back in the day - 1960's premium ( you old guys remember?) used only 0.25 to 0.4 gms/gal TEL in the top octane (SHELL 98 or SUNOCO 260)! Aromatics used in av-gas have a high RON (research octane (calculated No.)) but a poor MON (motor number measured in a test engine w/adjustable compression ratio) Rating on the gas pump are RON/MON averages (notice it says "RON+MON/2" on the pump? Your best blend components are Iso-octane, Methyl-pentane, Lighter components (butanes) are added/removed from the blend to adjust the vapor pressure of the fuel (to prevent summer vapor lock and hard starting in the winter), Hi-compression is needed to extract the additional power potential of Hi-octane fuels. The added power is a result of the increase in "squeeze" of the higher compression ratio w/o the fuel pinging or pre-detonating - which is bad. the power increase is from the longer burn time and increased compression in the engine. that is why the 13:1 CR motor runs like and scalded - dog on a race-gas blend. -2$en#e-
 

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Discussion Starter #20
We'll ,, three years later and here is the undersize of my heads.

I never did run 100% 100LL, I only ever brought home 1 litre cans of it after login the daily fuel tank sump drains to check for water.
I used to use the litre cans to top the bike up . So it was always diluted with standard UK pump 95 Octane fuel..but some times it could be nearly pure AVGAS...but not done so since early 2018...after that and a bike crash in the Czech republic 4th july 2018, I did not rid the bike again till Feb 2019, and but the time i went back to work in March 2019 they had got rid of the fleet of AVGAS aircraft and we are running JET A1 now in bigger aircraft

But what do you guys reckon to the state of the value seat and orange build up on the plug... Is that the damage caused by the 100LL?

The valve surfaces were the same.

I had been in Europe too, running the French fuel , with 10-15 % Ethanol...


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