Is 4 extra cubes worth it? If I was putting a 400 crank in a 350 block I'd say 30 extra cubes is worth the time and money but 4? Does it really make much of a difference? I currently have my motor apart and have to replace the Orings at the bottom of the cylinders so I'm thinking an overbore and pistons/rings may be in order. I almost have 50k on my bike and I am surprised to see the original ball hone marks in my cylinders. Is this normal? I also had what I felt was an excess of carbon build up on the tops of my pistons. I felt I had a good running motor but with all that carbon I can understand why I had some detonation issues on hot days. The carbon is gone. I cleaned them off. I plan on routing my breathers to a catch can rather dumping into the intake again so I hope that helps the carbon issue.