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Unused premix fuel


GEEZR

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I was just curious as to how long I can store unused premix gas before it starts getting weird .(octane decreases over time when mixed w/2cycle oil). I remember starting up my shee and riding it around for about 10 minutes, and it ran like crap with about a 1/4 tank of 6 month old gas. Then I put in a fresh batch of 32:1 with 91 octane as usual and it ran awsome. I'm sure premix will chemically change over time, but it's less than 6 months, I think. That's OK, I just use the old gas in my lawn mower (the unforgiving Briggs & Stratten 4poke) :biggrin:

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it depends on compression and timing as well as elevation. if you are not running on the ragged edge of compression and timing then youre premix can afford to lose some of its octane rating and still provide enough detonation resistance to keep you from blowing a hole in youre piston.

 

personally with these hot florida weather and my compression and timing i wont use premix in my banshee thats over 1 month old. i use it up in the weedwacker, chainsaw, blower and i will also sell it/give it away to family that has 2 cycle lawn equipment. finally as a last resort my car.

 

i have seen my dad use year old 97 octane premix in his chainsaw. that thing would ping really bad if you let the rpm's drop too low or used too much throttle. personally i hate seeing people do stuff like that but hey i cant save the world i can only do what i think is best for my stuff.

 

the banshee scares me because the exhaust and intake is so loud i dont believe i would be able to hear it detonating. therefore i figure its better to be safe than sorry.

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I was just curious as to how long I can store unused premix gas before it starts getting weird .(octane decreases over time when mixed w/2cycle oil). I remember starting up my shee and riding it around for about 10 minutes, and it ran like crap with about a 1/4 tank of 6 month old gas. Then I put in a fresh batch of 32:1 with 91 octane as usual and it ran awsome. I'm sure premix will chemically change over time, but it's less than 6 months, I think. That's OK, I just use the old gas in my lawn mower (the unforgiving Briggs & Stratten 4poke) :biggrin:

 

 

it doesnt decrease because it is mixed with 2 cycle oil , octane decreases because its stored in a plastic tank, if you store it in a metal tank it will keep its octane for a long time.

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it doesnt decrease because it is mixed with 2 cycle oil , octane decreases because its stored in a plastic tank, if you store it in a metal tank it will keep its octane for a long time.

Exactly. Light, humidity and temperature are gasolines enemies. A sealed metal can is the best place to store gas in, and keep the can out of the sun somewhere cool.

 

Race gas and av gas both have additives that make sure the gas stays fresh longer. Personally I don't worry about it. I ride enough that the longest my tank has the same gas is a few weeks, and the cans never have gas more than a month. (I use av gas)

Edited by dawarriorman
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Thanks for these tips, folks. Looks like I'm gonna use my 5 gal. plastic jugs for lawn mowers and weed whackers.

GMAC , I was just gett'n ready to ask that same question, octane boost as a compensator.

It's very rare that I leave any gas in my tank , I try to ride to the very last drop. I've just been too busy the last 6 months and just thought I'd fire up the shee with the little extra fuel that was left over in the tank , perfomance sucked :banghead:

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