CMSMJ1 wrote:mailed you Ricky

I never bother with polishing them, just make sure there clean and theres no huge carbon buildup, while it may seem like a little grinding can give you 'free' power its never that simple. each head is slightly different and the set-up of the bike will vary wildly.

£600 sounds ok depending on who is doing the work, but it depends what your after..

The inlet and outlet ports are cut into the head at specific angles, depending on set-up, sometimes a more direct or even different path into / from the head to what is there at present will give power gains for certain applications.. I.e. ram-air full throttle racing etc.

as you said Rick, polishing involves smoothing the walls of the port to improve the air-flow... depending on the application, head design and a million other factors this might improve or break things, there is a thinking that the rough-cast as been said helps to create air-turbluence which keeps the fuel / air mixture mixed well.

Unless you have a flow-bench or a lot of experience with these heads then its not really worth irreverisbly making something worse...

best thing you can do if you like to fettle is check that the valves are sealing properly and lap them in a little if need be (remove valve, depending on seat wear use a fine or a medium paste and using the sucker stick spin the valve backwards and forwards a few times)

cheers mart as ive said all im doing is mainly cleaning and just get the rough casting out of the exhaust port,

I wouldn't even bother with that... apart from cleaning it. especially if your bikes still not running sweet yet as you'll be inducing more changes. However, just messing with the exhaust ports I can't see cause any harm.. but then again I can't see it doign anythign either :D

just becareful