Sparks key & compresion question

[d90rick]

Ok, i know u dont want to run a key with any piston that is more than 11:1 due to heat, correct? Now, i was on the phone w/sparks they said the key is sorta like electronicallt increasing the compression. Now, with a 12.5:1 piston you need to run race fuel & no key. W/a 11:1 & a key u can run pump. So i wonder if there would be much of a difference between the two setups. Reason i ask is that i am rebuilding my motor & am debating on the sparks piston (12.5:1) or leave the key & run a 11:1 piston. Anyone with experience on the two?
This is for my xc race bike

Thanks!

[CJM]

Im almost positive 11:1 with key is a huge no no. Highest you can go on key is 10;1. Race fuel or not.

Honestly did the key to a friends 400, it didnt do a damn thing imho.

Build the quad with an 11:1 piston, stage 2 hotcam, 04-05 450r carb and a good pipe and it will fly. I nearly bested my buddies with worked 450rs in the woods yesterday. They have at least 10hp more than me. Rider ability more than makes up for less power as well.

[d90rick]

Thanks cjm. I started xc this year after being off the quad for nearly 20yrs. Did all the suspension, added sparks pipe & key. Need to rebuild the motor. Was thinking of throwing in the sparks 12.5:1 piston, cam, carb & have them p&p the head. Ran the A class after 2 C class races & placed 7th & 8th. Figured a liitle moreower (and getting inshape!) would help!

[CJM]

Quite Welcome Rick!

If you dont mind running race fuel then 12:1 or similar would be worth it. Just make sure you do have duty head studs and run the cometic brand steel gaskets.

The 450s can only go as fast as the woods dictate as well, so in the woods you can easily keep up or beat them if you have skill. Only place you may lose them is the straights or a wide open are. My buddy has a stock 400ex and keeps up with all our worked bikes, crazy stuff.

[d90rick]

I dont mind race gas, i really like the smell...
I thought about going nuts & throw in a 4mm stroker crank too...

[gasguzzler]

I have a 12:1 JE piston, a +6 degree spark key, and a programmable dynatek. I've set it up for +2, +4, and +6 equivalent set-ups and can't say I've noticed much of a difference between them all. I'm running on straight VP of course:D