Piston help!

[CANAMracerdad]

There really wasnt 2 part #'s , there was just a lesser tolerance ....... but as stated , the cyl should be measured , and the proper size ordered .
Either will go in and work , how long the motor will last .....depends on the fit of the piston .

[gregory]

The voice of reason lol

[fast507]

DON'T RUN 13:1 on Pump gas!!! That's a sure recipe for a grenaded motor. Detonation = valve troubles, burnt pistons, high head temps, and a whole list of problems. Don't try to cheap your way thru it. If you're gonna do it, run a minimum of 108 octane fuel, install a good programmer to feed it the right amount of fuel and try to find yourself at least an exhaust cam to run in the intake side til' you can do the head work.

[gregory]

and the green injector

[OrangeR]

13:1 on pump is ok, as long as you dont have a ton of head work done. Ive been racing and riding my quads and dirtbikes with 13:1 pistons in them, for a few years now, and Ive had no problems with pistons or valves.

I talked to several engine builders, auto and bike, before i made the switch, so i did do my homework, all said id be fine.
Every now and then, id throw a few tanks of 104 octane in there, and it did feel a little crisper, but it was also slightly oxygenated fuel.

Most engine builders are going to recommend race fuel, in order to get the most out of the work done, not to mention the other benefits to leaded fuel. Ive had builders tell me to run everything from Av gas, to c12, to 110, and others say 100 will work. Ive tried them all, and know what works better than others, but at this point in my racing "career" ha, i want cheap and reliable. my built 13.6:1 on 110octane, i went through 2-3 pistons a season, cammed/stock head 13:1 on 93, would get a full season.

[CANAMracerdad]

Then you were not running a real 13:1 ...... the piston alone will not do it .
( run a compression test and PM me !)
at a REAL 12.5:1 ratio, the engine will begin to pre-ignite at operating temperature .
My motors do ? just sayin ???
But then again , we run 110 in our stock motors to prevent carbon buildup .
PLEASE ....PM Me with your compression in PSI !

[gregory]

Ya ive never seen,built or rode any quad that had hi compression pistons . That didnt need atleast 103 to run correctly. But thats what i know ,just my two cents. But really why even go to high compression if your not going to run some kind of race fuel? And plus our pump gas here in the usa is really dirty so using race fuel is just a better choice just on that fact.

[OrangeR]

im definately interested to see what the compression test reveals. My can-am is a neatv production class legal bike now, so stock everything, piston, head, valves.. etc, but when i get my dirtbike back together, ill do a test and get back to you guys.
I wouldnt doubt that the pistons im running are not a true 13:1, but then again, nothing is really what they advertise it as, anymore, lol.