high compression vs. low compression

[z400bs]

Is high compression really worth it? I am a college student and race just local districts when I can. Is it worth it to go to a high compression piston or does and aftermarket stock compression piston make plenty of power? I also see that sparks racing makes a low compression big bore kit. Does anybody have an opinion on that? thanks.

[01boneless]

4 strokes love compression. thats where you get power BB kits are worthless without high compression. get a 12:5:1 JE or cp 160 bucks and youl see a diffrence

[z400bs]

does a 12:5:1 piston require race fuel?

[01boneless]

nope its fine but since i just noticed you have a 06 i belive they come stock with 12:1 so the 12:5:1 wont do much sorry i just noticed umm you could get a cam or port and polish ?

[z400bs]

yeah I already have a cam. And i could still bump the compression up to 13:1.

[01boneless]

sure could if you want to buy race gas :D

[TJ Bradley]

If you want to bump compression up a little then throw a Crf head gasket on there. Theyre a 2 layer instead of the trx 3 layer. It'll bump your stock 12:1 to 12.4:1.

Then if you still want more power bolt a Crf head on it. HUGE improvement. Bolts right on easily. My 08 with the Crf head and a 14:1 Cp piston pulls my buddies High Comp Ltr 490, and is about dead even with his 510. And another guy i race with has a Trx477 big bore at 13.5:1 with a dasa head and i pull him pretty steadily even tho i weigh 60lbs more.?? Dont know why, just stating the facts. lol. I was amazed at how well it turned out with the swap. And def. cheaper than sending a head to Baldwin or DASA and getting a full build with oversize valves done.

[z400bs]

Whats different about the crf head? and how much can you pick one up for?

[fomospede]

go for the crf head gasket
put plus 1mm exhaust valves

i run the 13.5 piston wiseco
and the step up on the valves really helped it breath
i love the smell of race fuel!

ok so 93 octane is 3.75 a gallon and cam2 112octane is 5.75
fuel brings out alot of power as well
i mix mine with EO fuel to get 100 octane it runs super and when i do the math its under 5$ a gallon

EO = ethanol free fuel
ethanol sucks as*

:D my .02

[TJ Bradley]

The Crf head has WAY bigger ports and better angles along with +1 valvetrain over the Trx. You can usually find a nice one on e bay for around $400. Do the Crf head and gasket and youll have a Stout reliable motor that you can run pump gas on.

[BlaineKaiser450]

You can still build a powerful and reliable motor with 12:1 compression, but there is definitely a large difference when you have that same motor but with 14:1 or similar. But remember motor isn't everything, put John Natalie on a stock motored quad and he will still smoke all of us haha

[01boneless]

Originally posted by BlaineKaiser450
You can still build a powerful and reliable motor with 12:1 compression, but there is definitely a large difference when you have that same motor but with 14:1 or similar. But remember motor isn't everything, put John Natalie on a stock motored quad and he will still smoke all of us haha

this its about corners right shock setup and lots of other stuff besides motor. BUT.... alot of power is nice to have when you can handel what it put out.

[TJ Bradley]

And remember with alot of power comes alot more arm pump. lol. The harder it pulls the harder you have to hold on. . . Untill you get more used to it. It took me awhile. But my set up is a little more snappy than id like it.

And as blaine said above, suspension and handling are most important. Power is just good for holeshots to a point. the rest is rider