Hey i was wondering if anyone can give me a fairly safe premix ratio for my 910 i bought it used it seems to smoke quite a bit he said it was mixed at 30-1 due to breaking in new jugs but im seeing numbers up as high as 60-1 that seems a bit steep to me. Any help would be great thx.
premix ratio 910 crankshop motor
- Thread starter RMKsledmonkey
- Start date
100% premix
F
freak58trio
Member
I run 32:1 in my 800
I talked to Curt at FTX and he say's mix until it fouls out then back it off till it doesn't foul anymore.
I talked to Curt at FTX and he say's mix until it fouls out then back it off till it doesn't foul anymore.
Great thx for the info guys now i just need to get a straight answer from crank shop as to if it will run on pump gas or if i need to add octane boost as well.
Thx for the help !
Thx for the help !
engine warm, plugs out,throttle wfo, hook up compression guage and pull as fast as ya can maybe 5 times and see what she pumps. That will give you a good idea of cranking comp and we can go from there as to the octane aprox needed. Depending on the head the 903/910/935 motors can be a 25% RACE gas mix to 100% c14. Also depends on which cdi and stator your running and the timing curve put into it. But as a rule of thumb 120 lb or less is GOOD 91 octane unoxyegenated pump, 120 to 135ish is about 25% race, 135 to around 155ish 50-50 or 100% 100ll av gas, 155ish to 175ish 75%+ and anything over that you better be running 100% VP C14 or better. And if its over the 155 level I would start on the high end of race gas blend and wean it down as you go.
It is also good to check cranking comp at your riding elevation, lets say you pump 160 at 2500ft, then you pump 125 at 10,000...now at elevation you will make most power at a 25% blend, but at the parking lot you need 75%..sooooo ya gotta ride real real easy till you get up there or carry a few gallons of 85 octane pump to mix in to drop ratio up high..ect ect...really high compression motor are a pita as the gas mix and jetting greatly affects power output. Also get real good at reading plugs, egt's a must, and run the gates GT series h2o pump belt (see my other thread) good luck they are good motors.
Oh, also based on 30 years or owning a race engine shop 99.9% of octane boosters are CRAP in a 2 stroke, run a blend of 110 leaded race gas in these motors of a av gas blend.(treat av as 95 octane to be safe)
It is also good to check cranking comp at your riding elevation, lets say you pump 160 at 2500ft, then you pump 125 at 10,000...now at elevation you will make most power at a 25% blend, but at the parking lot you need 75%..sooooo ya gotta ride real real easy till you get up there or carry a few gallons of 85 octane pump to mix in to drop ratio up high..ect ect...really high compression motor are a pita as the gas mix and jetting greatly affects power output. Also get real good at reading plugs, egt's a must, and run the gates GT series h2o pump belt (see my other thread) good luck they are good motors.
Oh, also based on 30 years or owning a race engine shop 99.9% of octane boosters are CRAP in a 2 stroke, run a blend of 110 leaded race gas in these motors of a av gas blend.(treat av as 95 octane to be safe)
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Nice thing about 32:1 is that its easy to figure.
Octane boosters are useless, buy good fuel.
I run 25% mix in my Carl's 910 of Av gas and pump premium. I have the high compression head and ride about 7000 feet. I have yet to see any 910'ish based motor that didn't require at least 25% av or race gas.
sled_guy
Octane boosters are useless, buy good fuel.
I run 25% mix in my Carl's 910 of Av gas and pump premium. I have the high compression head and ride about 7000 feet. I have yet to see any 910'ish based motor that didn't require at least 25% av or race gas.
sled_guy
awesome info guys that helps me out a lot, im running 125 even on both right now so im gonna start with the 25% mix and ditch the octane boost idea im guessing i could pick it up at most race shops in a seperate jug and mix it in as i fill up. Really appreciate all that info i get a one line answer from crank shop saying "If your running one of OUR motors then it will run on pump gas if it is a polaris bottom end then you will have to check with the manufacturer.."
Thx again!!
Thx again!!
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