13-1 compression vs stock??

[kazpr]

Will you see a major difference w/ the hrc cam and a hmf pipe and no airbox? Race fuel also of course.

[RedRacer44]

heh, I always seem to have input for you....dont mean to be a nuisance....

I rode one of my buddies 450R,....he has a full NMotion exhaust, HRC Kit, FCR carb, and the 13:1 Wiseco. All I got to say is WOW! It was ridiculous.....it was a day and night difference between his motor and my motor. You know what my mods are and my quad has good power but WOW, that was ridiculous. It pulls SOOO HARD off the bottom end and keeps pulling with the HRC kit. He runs VP Ultimate 4 as fuel and that stuff smells SWEET! Haha!

I made up my mind after riding his quad that I was going to get the 13:1 piston....going to take 'er in for the work next week. Its definitely worth the modification if you're going to be race MX and have the $$$ to buy race gas. Also makes GOBS OF POWER!

[kazpr]

Red what was his @ on dyno?

[RedRacer44]

He hasnt dynoed it yet but JH has a similiar set up on one of his TRXs, and he's pushing out 52 HP. I'd bet he's pushing around 50 HP easily.

[kazpr]

Ok cool I need to get a AIM setup so I can chat to you on there easier :)

[allmixedup047]

Originally posted by RedRacer44
He hasnt dynoed it yet but JH has a similiar set up on one of his TRXs, and he's pushing out 52 HP. I'd bet he's pushing around 50 HP easily.

wow, those are some awsome numbers. mine hit 40.5 with just the HRC and 13t front sprocket. i bet its a torque monster also.:macho

[#1speedbump]

Kaz, check out trx450r.org, there is a thread about the fst 500 vs a hi comp piston and the results were suprising

[chris450R]

i would just really like to know what the best hi-comp piston would be for mx? all i have done right now is a full sparks exhaust. soon i am going to get a '03 crf carb and '04 crf cam. so which one 11.5:1? 12:1? 13:1? 13.8:1? which one there are so many?:confused:

thanks, chris

[RedRacer44]

The best piston probably for power is going to be the 13:1, 13.5:1 or the 13.8:1 piston....either of those will make loads of power. Especially with the FCR carb and crf cam....

[iceracer65]

I've talked to guys at the TT's that are having problems with the high comp pistons touching the valves at higher revs. Even with titanium valves and the heavier springs. That's not something I would wanna deal with. These same people are telling me the hotcams aren't worth anything and the sparks cam and the hrc are very similar. Mine made 44 on the dyno with the hrc kit and a pipe, are you suggesting that a piston is worth almost 10 horse?? I know for a fact that a good port job is worth 2-3 hp throughout the revs. I guess I would rather have some reliability than a couple of hp.

[kazpr]

No names here but talked w/a couple of pro MX racers and they really seem to like and suggest the 13 pistons and the HRC cams.

[allmixedup047]

Originally posted by iceracer65
I've talked to guys at the TT's that are having problems with the high comp pistons touching the valves at higher revs. Even with titanium valves and the heavier springs. That's not something I would wanna deal with. These same people are telling me the hotcams aren't worth anything and the sparks cam and the hrc are very similar. Mine made 44 on the dyno with the hrc kit and a pipe, are you suggesting that a piston is worth almost 10 horse?? I know for a fact that a good port job is worth 2-3 hp throughout the revs. I guess I would rather have some reliability than a couple of hp.

i dont know what it puts out but the nmotion pipe is supposed to be top notch, i bet it would add 6 with cam and piston, so if he estimating the bike to hit 50, that would mean the piston would add 4hp. might be a little high but not to far off.

[RedRacer44]

he's also got port work too, sorry.....forgot about that! my bad....but we're also only seeing 3-5 HP outta port work. My buddy has a full Sparks 450R motor and he's pumping out 58 HP so take that as you will. I just listen to credible sources and dyno #s.

[allmixedup047]

Originally posted by RedRacer44
he's also got port work too, sorry.....forgot about that! my bad....but we're also only seeing 3-5 HP outta port work. My buddy has a full Sparks 450R motor and he's pumping out 58 HP so take that as you will. I just listen to credible sources and dyno #s.
get that quad on a dyno cause i want to see what kinda numbers it puts out!:blah:

[iceracer65]

Yea that makes a little more sense... if you want to build a full race motor that is going to need a rebuild once a season than the high compression is the way to go...just hope that nothing lets go when you are leading, or worse yet, coming off the face of a jump.:eek: :eek: :eek: :eek:

[allmixedup047]

what prices has everyone found on the hi-comp pistons?

[fearthis_450r]

hey redracer44 how do you like your stage 2 hot cam? I am thinking about getting the stage 2 cam, sparks exhaust, 13:1 piston, and a cdi box. Who do you think that will work out for me i already have a dyno jet kit and K&N air filter?

[RedRacer44]

JH Racing has the hi-comp pistons from around $150 - $160, I THINK! The 13.8:1 is a lil' more expensive than the rest.

I love the cam, it works well for me. I can rev the motor out longer now and it will keep pulling, which is nice on the MX track. Major power was felt in 2nd - 4th gear. My piston choice was poor though, i'm not happy with it. Thats why I'm getting the JE 13:1 piston....


Fearthis....if you do those motor mods, you're quad will run very well! No worries there my friend, top it off with the FCR carb maybe and you'll be set. I hope you'll be using it for MX, because thats a lot $$$ to be dumped just for trails or dunes but hey, if ya got the $$ go for it!