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SicRipp83
10-20-2009, 05:54 PM
hey everyone time for a top end my quad has a hrc kit i want to put a higher compression piston in i like the je pistons so i nhave my brand i just dont know what compression to run i want to still run pump gas the quad is a 2007 er thanks

10-20-2009, 05:58 PM
12.1

S.A.J
10-21-2009, 04:51 PM
CP you can run a 12:5:1....Just sayn...

Ex'r Marlin
10-24-2009, 02:32 AM
I had a 12.8 to 1 compression JE Piston in my 2006 TRX450ER, and when the piston went, and my mechanic tore down the motor, he noticed signs of "pre-detenation" (sp?)... And I was running 50/50 (50% VP110, and 50% pump gas).

I do not know when I should have preformed a "preventive maintenance" and had the piston replaced, but because the piston broke, it cost me a new crank, cylinder, and head!

Like stated above, if you want to run "pump gas", I too would agree keeping the stock compression... and purchase a stock piston.

NOTE: I will admit that I do miss the difference between the 12.8 to 1 JE, and now back to stock set-up... But unless you are going to run race gas, I would not recommend the "higher compression set-up".

Good luck!

Ruf Racing
10-24-2009, 08:31 AM
Originally posted by Ex'r Marlin
I had a 12.8 to 1 compression JE Piston in my 2006 TRX450ER, and when the piston went, and my mechanic tore down the motor, he noticed signs of "pre-detenation" (sp?)... And I was running 50/50 (50% VP110, and 50% pump gas).

I do not know when I should have preformed a "preventive maintenance" and had the piston replaced, but because the piston broke, it cost me a new crank, cylinder, and head!

Like stated above, if you want to run "pump gas", I too would agree keeping the stock compression... and purchase a stock piston.

NOTE: I will admit that I do miss the difference between the 12.8 to 1 JE, and now back to stock set-up... But unless you are going to run race gas, I would not recommend the "higher compression set-up".

Good luck!

I have run a 12.5:1 compression on 93 octane with no issues. You mixing 50/50 at 12.8:1 IMO, should have been fine. In theory any compression under 13:1 would be fine running 93 octane.

JParisi48
10-24-2009, 09:10 AM
i have a je 13 8 1 and i love it.... its my 2nd piston in 2 seasons so i think thats pretty good.... only reason i had to change the first one was because the crank went and wiped out my motor

BlaineKaiser450
10-24-2009, 07:51 PM
I have a CP 12.5:1 and i run 91 and have run 89 when money was tight without problems

SicRipp83
10-25-2009, 04:49 PM
so in peoples opinion who makes a better piston cp or je i have herd good about je but never herd anything on cp