Chad.. Question for ya

[leadfoot_52]

I have a buddy with an 06 CRF250r and am looking to go more than 13.5:1 compression, but i cant find a piston that offers more compression. Do you know of anyone who makes a higher compression piston without having to mess with the cam timing? Or can you custom make a piston for that?

[chad502ex]

Originally posted by leadfoot_52
I have a buddy with an 06 CRF250r and am looking to go more than 13.5:1 compression, but i cant find a piston that offers more compression. Do you know of anyone who makes a higher compression piston without having to mess with the cam timing? Or can you custom make a piston for that?

Before manufacturing a piston higher than 13.5:1 CP shelf, if I were you I would consider decking the head a few thousands....

sure, cam timing may change a few degrees, but nothing to worry about at all...

instead the shelf 13.5:1 CP Piston and deck the head and bingo!

[leadfoot_52]

ok- how much should i get the head decked? and what difference will a few thousands make?

[chad502ex]

Originally posted by leadfoot_52
ok- how much should i get the head decked? and what difference will a few thousands make?

decking a head 0.010 - 0.040" can make a big difference in increasing compression ratio.

exactly how much of an compression increase shaving a head depends on the cylinder head compression chamber volume change from before the machining to after.

...but, i dont suggest shaving a head without completely understanding how much your application will permit you to shave. This is determined by claying in an engine. Also, there are concerns with shaving with a change in camshaft timing and cam chain tension, but not a big deal if you know what your doing...

If your unsure how to calculate, measure, and target a desired compression, I would suggest you sending your engine to a builder who does... ;) :macho

good luck.

[beany]

Chad, are you looking for work???:rolleyes: Hopefully not in search of it I know it should find you. Hopefully we'll be speaking later this fall. :)

[chad502ex]

Originally posted by beany
Chad, are you looking for work???:rolleyes: Hopefully not in search of it I know it should find you. Hopefully we'll be speaking later this fall. :)

LOL! naaa not looking for work, but you can never have too much tho... hehe.

actually, work is doing well with yamaha porting, honda full builds, top end rebuilds, my piston getting ready for release, taper boring carbs ignition R&D.. ect..

I look forward to working with you though...:cool:

[chad502ex]

getting back to the crf250,.,

for some reason i really like the valve cutout shape of this crf250 factory piston....;)

check out the tulip valve reliefs,....:macho