According to the engine calculator, if you run standard bore (4.126")with 3.75 stroke, gasket bore 4.190, compressed gasket thickness .039, 60cc 305 heads, with .083 dish pistons, it calculates out to 12.92:1 compression. You can download the engine calculator,but I don't remember the web site. If you look back through the bulletin board postings under engines you can find it. Be sure to check valve clearances.
[ June 18, 2002: Message edited by: agb1758 ]</p>