Harley-Davidson spells hundreds of dollars for your shop
This article covers the proper way to port and polish Evo and Twin Cam 1998 to present cylinder heads with or without valve guides in place. My way to do a great valve job and maintain the 89% throat dimension for intake and exhaust ports will achieve the highest horsepower and torque numbers in the country. I will briefly touch on cams, but the most important component of these Harleys is the big bore kit with real, usable compression ratios on today’s gasolines. We will discuss how to bore and hone the barrels to keep them straight and round.
Cryogenically freezing the heads, pistons, rings, and barrels; then applying high heat and lubricity coatings make for a cooler running bike with no detonation — even on the 10:1 and 11:1 for street use. When using the higher ratio pistons a compression release valve needs to be installed in the cylinder heads.