I bought a used set of stock Sportsman II heads last year and I want to take them in to have them magnafluxed and freshened up. My motor is in my signature. I have stock 76cc 882 heads now with about 8.25- 8.5 compression. My SPII's are 72cc's. I'm guessing I'll gain .4 point of compression with the switch. How much can I safely mill without going to an angle mill?. Which head gasket do you recommend?. I want to raise my compression to about 9.5. I was thinking 30 thousandths off the heads would get me .5 and then maybe a thinner gasket would get me up in that range. Any advice or experiences would be appreciated.

The 72 cc heads would bump CR from 8.5 to 8.97.

Your typical headgasket is 0.040" thick. If you go with a shim gasket, say 0.015", you would get 9.36. Or you can use a regular 0.040" gasket and mill about 0.030" off the heads and get about the same (probably a little less) CR. With the thin gasket AND 0.030 milled you're looking at approx 9.6:1. You should measure the chambers on the heads before and after milling so you don't get any nasty surprises.

Thanks zwede. What do I use to measure the chambers?. Are there any downsides to using a thinner gasket?. I'm assuming my local speed shop would have the thinner gaskets.

You should be able to find inexpensive measuring kits in summit/jegs etc. Or you can make your own. You need some plexiglas to cover the chamber. Drill a hole so you can add fluid. Use water with a drop of detergent to reduce surface tension. A few drops of candy coloring makes it easier to see. Finally a syringe in the 10-20cc range. Add fluid with the syringe until full and you'll know the chamber size. Of course the valves will have to be installed as well as a spark plug.

Downsides with a thinner gasket is that the head and block surfaces have to be better (no warpage or irregularities).

dont put a .015 gasket in unless you know how far down the bore the tallest piston is at TDC you want a .040 quench so your if your piston is .025 down the bore at TDC a .015 would be perfect BUT if your piston was at .00 deck hight and you used a .015 you would smack the head with the piston,hope that helps

Thanks for the replies