How high of compression can I go with and still be run on 91 pump gas? This will be in the sand dunes also so...we all know sand is very hard on a motor. 13:1?
thanks
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Make my F@ckin day punk
How high of compression can I go with and still be run on 91 pump gas? This will be in the sand dunes also so...we all know sand is very hard on a motor. 13:1?
thanks
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stock is at the very limit of pump gas, which I believe is 12:1.
85/86 atc 250r, very modded, lrd 310pv, +1 lsr, shortrack kit, cr250r igntion, 39 pwk, paul turner hi-rev pipe, propeg nerf bars, HREATV custom frame,
86 atc200x- 84 250r exteneded axle, supertrapp pipe, 27mm carb, works rear shock, 84 250r front end(rebuilt w/ terry kit), 350x tripples, ported head, 12:1 piston, webcam,
crf450r quad, lsr frame, swinger, antifade, hyper beadlocks and the best of everything else.
88 trx 250r pced and reinforced frame, +3+0 t-pin, 310pv, cr ignition, 39 pwk, lsr rear end, elka shocks, aftermarket radiator, lrd pipe
06 ktm450exc, full skid plate/guards, radiator fan, clarke tank, dual sport kit, reg/ins/insp, steering stabilzer
98 200exc: street plated, skid/guards, dual sport lights, stabilizer and more.
07 ktm 250xc, skids, reg/ins, dampener, good lights
2011 atc450r in the works, suspension and details need to be worked out
I don't have stock tires
Not at all, but compression is surrounded by opinions and myths.Originally posted by deathman53
stock is at the very limit of pump gas, which I believe is 12:1.
Who's right? Who knows...
Lots of people are running 13.5:1 on pump in CRF motors on MX tracks. BUT that's with aftermarket cams also.
It all depends on your skill, riding stlye, cam, etc etc. Lots of variables.
For a stock cam in the dunes, I'd say a 12.5:1 would be very safe.
Aftermarket cam I would run 13:1
250f's are running 12.5:1 from the factory all day long.
Those are being way on the safe side too, you could easily bump it up a 1/2 of a pound if you'd like.
2009 CRF250R
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engine performance guru
I have been running 13.5 to 1 in my 426 with stock cams with pump fuel for the past 2 yrs now.For the dunes make sure you go up a size on your main jet as the motor is under more load at the dunes.
426ex,lt250r banshee and kfx700 v force,yz250 mx bike
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