13.5:1 piston

[LTZ400rider]

for all yous using a 13.5:1 piston what kind of fuel are you using. can i mix 110 and 94?

[Chino]

Originally posted by LTZ400rider
for all yous using a 13.5:1 piston what kind of fuel are you using. can i mix 110 and 94?

i wouldnt, i runnin 13:1 i run anything over 110 straight. no, mixin ~

[Cody_300ex]

Or if you don't have to worry about money, I would run VP. I think its called ultimate four, not sure.

[LTZ400rider]

thats what im sayin vp fuel mixed with 94 pump

[TGW_400ex]

Originally posted by LTZ400rider
thats what im sayin vp fuel mixed with 94 pump

I thought pump gas was 93:huh

[Cody_300ex]

Originally posted by LTZ400rider
thats what im sayin vp fuel mixed with 94 pump

No you need to run it striaght, 100% VP. Or run 110 octane.

[2muchquad]

i run 13.5 compression and mine runs fine on 93 octane,i tried a lil mix and i really couldnt justify the expense.by the way my 426 motor has 12.5 to 1 stock. this motor is high performance and it lives so im sure the xr trail bike based motors will be fine with the stock cams

[shamisc]

Originally posted by 2muchquad
i run 13.5 compression and mine runs fine on 93 octane,i tried a lil mix and i really couldnt justify the expense.by the way my 426 motor has 12.5 to 1 stock. this motor is high performance and it lives so im sure the xr trail bike based motors will be fine with the stock cams

WHAAAAAT???:huh :huh You're headed for a hole in your piston. Laz said anything over 13:1 really should run alcohol! There's probably alot of pinging going on in there!:eek:

[2muchquad]

nope,runs fine,almost a year and a half now.one thing to consider is compression is also also tied in with the camshaft duration.im not going to get into all the specifics(do some research)but if both valves arent completely closed at the start of the compression stroke(again cam duration)some of the mixture will be lost ,therefore the "stated"13:1 compression really isntas badas it sounds.there have been motor testedwith 16:1 compression(OUCH!) that survived with the necessary cam timing and ignition timing adjustments.read up on this;)

[LTZ400rider]

im gettin the 13.5:1 piston and dont wanna drain my weeks paycheck on fuel. and sunoco has 94 octane

[cummingetit]

Altitude makes a difference also.

[LTZ400rider]

sea level, stock pipe, slip on soon tho, im gonna put a intake cam in (hot) and gonna rejet and open the airbox

[shamisc]

Originally posted by LTZ400rider
im gettin the 13.5:1 piston and dont wanna drain my weeks paycheck on fuel. and sunoco has 94 octane

Don't wanna spend cash on gas, I wouldn't get the piston. It's gonna wind up costing you a wad in the long run! Probably taking several paychecks!:( 11:1 or less, pump gas is fine; over 11:1, pump gas is not an option!