OEM or high compression TRX piston in 450x?

lycominghunter · Joined: 12 Jun 2012 Posts: 8

I want use a trx piston in my X because I ride it on the road, but I don't know if I should go for the OEM TRX or a higher compression ratio JE piston.

I know that only 2006 and newer TRX pistons will fit my 05 X.

Also, what ratio TRX piston is the max I should go if a higher compression ratio is the way to go. THANKS!

crfsonly · Posted: Fri Jun 15, 2012 10:45 pm Post subject:

either will work and i'd stay at 12.5 just to make sure you can use pump gas without issue at all altitudes. je pistons are typically lighter and a bit stronger but the OEM pistons from Honda are durable and a good value.

ken

curryd · Posted: Sat Jun 16, 2012 7:20 am Post subject:

I had a 11.5:1 JE piston in my trx 450r quad. Very excellent pistons. I had 4+ years on piston. Very high quality. I believe they have a little higher one know that you can run pump gas yet. I try to run 93 octane in mine and it has been "bulletproof" so far.

lycominghunter · Joined: 12 Jun 2012 Posts: 8

I am assuming you had a pre-2006 trx? Because, if I understand correctly, the TRX bore and compression changed to 96mm and 12:1 in 2006.

I found a JE TRX Piston that's 12.8:1 which would be pretty awesome. But, you've got me concerned Ken. I'll be riding maybe up to 5,000 feet max. I have to 02 R Cam (I've read that cams can have an impact on what octane gas you need).

I know its not 12.5:1 like you recommended, but how about 12.8:1? Smile

crfsonly · Posted: Tue Jun 19, 2012 10:05 pm Post subject:

you'll be fine with a 12.8 on premium pump gas as long as it's well jetted and the premium is actually a premium octane.

ken

lycominghunter · Joined: 12 Jun 2012 Posts: 8

ok, but it still kind of worries me.

I know that one of the gaskets (head or base) is thicker than those used on the X. If I used the thinner gaskets from the X then that is going to increase my compression ratio above 12.8 and make knock even more possible.

1) So, I think I should use the thicker trx gasket to retain a true 12.8 CR and not go above. What do you think.

2) And does anyone know if its the base of head gasket on the trx that is thicker?

3) And is there any chance of the valves hittin the piston with only a 12.8 CR piston?

Thank you so much for all of the help. I really appreciate it.

crfsonly · Posted: Thu Jun 21, 2012 9:52 am Post subject:

you could get even more detailed in your concerns as valve dish, difference in CRF/TRX head, etc. will alter the compression. i haven't measured the TRX head gasket so i don't know the thickness difference but you are correct a thinner gasket will increase the compression. no need to be concerned about the valves/piston contact unless you change pistons outside the normal profiles.