Kenny at S&S did the porting, he's a local guys who builds motors here in Puyallup, WA. I believe the domes are 19cc and the Compression was around 180 psi. I've had them sitting in my garage for a few years now. I dont think they need to be bored, maybe just hone them. The left cylinder has some marking on it but nothing that your finger nail gets cought on. The bike ran great I liked the power. I ran 110 race fuel. My buddy that had the same setup got his bike dynoed at 65 hp with 35mm carbs. I found a great deal on a cheetah motor few years ago and switched top ends. I'm selling beacuse i need a new 4mil crank now. Thanks