100 Octane Low Lead Avgas in the Max
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lankeeyankee
Well-Known Member
Unless you are running high compression pistons the higher octane is only going to hurt your performance. The higher the octane the lower the flash point. To get the most power out of an engine is to run the lowest octane before detonation. If you look in the owners manual it specifies to use 86 octane.
You wont hurt anything but you may get more carbon buildup in the combustion chamber.
86? Really? Is that measured the way we do octane in the US?
I guess I'll just have to hammer it everywhere I go until I run the 100 out. Oh darn...lol:rocket bike:
KJShover
Proud Vmax lover
Avgas 100LL can be used in some motorcycle engines. It has about two grams of lead per gallon vs. Unleaded which Contains no more then 5/100th of a gram of lead per gallon. Lead is/was used in fuel as both an octaine booster and lubricant. Now there is chemicals in fuel that do the same thing without the side effects to humans and the environment that the old "Regular" gasoline caused. Unfortunately Avgas 100 LL sometimes has a high level of aromatics, which may lead to sluggish throttle response.
There has been talk among other riders and car owners of their rides running on the lean side and hot. I’ve ran avgas straight and mixed with unleaded in my bikes for many years (not my new max, but my KZ, XS and even my '85 Venture) in bikes with compression ratios comparable to the Vmax (10.5:1, 10:1, 11:1) and haven’t had a lick of problems, but I was jetted a tad on the rich side.
If you are running it, pay close attention to your fuel system i.e. hoses, fitting etc. as this can be worn and start leaking. What I picked up while working at the fuel refinery up here is octane rating is just the additives that prevent knocking; the core fuel is basically the same. Don’t get me wrong, that dosen't mean you can go out there and start blasting 130 rated fuel.
If you cut your 100LL and regular fuel 75% LL and 25% unleaded you should be fine. Just keep an eye out for a lean condition.
Copied from owners manual :
"Your Yamaha engine has been designed to use regular unleaded gasoline with a pump octane number ([R+M]/2) of 86 or higher, or research octane number of 91 or higher. If knocking or pinging occurs, use a different brand of gasoline or premium unleaded fuel. Unleaded fuel will give you longer spark life and redused maintenance cost. If unleaded gasoline is not available, then leaded regular gasoline can be used."
Cool. Thanks.
I'll just divide up the avgas among my gas cans and fill the cans the rest of the way up with 87. I'm not using it cosistently, I just have 15 gallons, actually 11 now since I filled up yesterday, that I don't want to go bad just sitting in my garage waiting for the next dunes trip.
Rusty McNeil
Well-Known Member
Ditto, on the loss of power and possible carboning of the engine; although I wouldn't think running a tank or two would get you there:ummm:
Nothing wrong with running the 100 octane probably. But engines definitely make thier best power when right on the verge of detonation.
After installing my Dyna 3000 I ran some 104 from the pumps at the track in order to try to take advantage of being able to give the engine more timing advance with the Dyna.
I couldn't find any advance curve that would make it act right; including the base timing curve.
Apparently the Vmax had all the advance it wanted with the base curve even running high octane.
With 87 octane it runs great with timing on the next curve up from base, and also the best times.
Rusty
