:dunnoany ever tried to put a 600 head on a 750 bottom end
Darren, just to help you out, I'll even pay for the shipping of those shitty Yosh cams and the useless flowed head to Australia, and dispose of them for you... LOLBob Farnham did some motors in this vein some time ago, using a 600 bottom half, coupled to a 750 barrels/pistons/head etc. It resulted in a torquey motor of 700ish cc's. No real gains in raw horses, pretty much between a 600 and a 750 but very tractible.
What I'm not getting is where the alledged gains are coming from with the 600 head on a 750 motor though. If the 600 runs a smaller port, then that will move power lower in the revs, as GSXR-Freak says, and maybe pick 1 or 2hp up from a (much) higher compression ratio.
Ultimately, when tuning a head, you enlarge the ports, which allows better flow at higher rpm's. What you sacrifice is low speed (engine) performance. So moving to a head from a smaller engine will do the exact opposite of what the conventional tuning route leads us to. A head for a fast road motor will have smaller ports than a motor built for out and out race use, to keep the gas speeds up in the port, to aid low rpm power.
If 15hp is on the table for a 750 from a head swap, I'll take the Yoshi cams and flowed head off and throw a stock 600 head on and save myself all the hassle...................:scratch