powerstar head questions

[jas250r]

I've got a nac's powerstar head, and was thinking of going down a dome size when i rebuild the topend. I believe the size now is a 21cc. I was on nac's site and the only optional size was a 19cc for the o-ring head like mine. Looked at dennis kirk and found the same thing for a o-ring head, 19cc. But for a cool head that takes a head gasket you can get a 18cc. Is this because running the o-ring head drops the dome size by 1. how much of a difference does 1cc smaller make? i mean is it worth the cost?

[C-LEIGH RACING]

You do know the Pro Design cool head dome wont be cut like the Nac's Powerstar dome, right.
Pro Design has a o ring style head as well, might not be listed in the Dennis Kirk catolog though.
1cc will make some difference with the dome, but I dought if even a Pro rider could tell the difference.
Neil

[jas250r]

when i said i was looking at the prodesign heads on dennis kirk they were the o-ring head. (o-rings instead of the head gasket) so understand what i was meaning. i know the pro design domes don't have the star. from what i've read on here the domes will interchange between the two brands? And when i said 1cc change it should've been 2cc change (21 to a 19) not there will be much of a change there. on nac's site they show all the powerstar stuff sold out, so i guess it will be dennis kirk when the time comes. any more gain from a custom dome? i seen this on dennis kirk or rocky mountain. you need some specs on the porting

[C-LEIGH RACING]

Yeah I see where you said that, sorry I missed it.
I've never had a Powerstar head from Nac's so couldnt say if the domes would interchange.
I think, but dont know where I seen it, might have been on the Nac's site, that TC Racing machined the Powerstar heads for them, not 100% sure on that though.
That head was surely different & thought about trying one but never did.
The most perfect head dome you could cut that would perform like ones suppost to would be cut just like the dome on the piston top, concave shaped, hardly anyone takes the time though.

Port specs, ??? I dont understand, you mean for the dome size, yeah I guess & what rpm your thinking you probably will be running the engine at most of the time, that will help.
Neil