Iam glad to see other babyboomers on this site.As a teenager in Bermuda in the late 70s we souped up our mobys.Back then performance parts were available.I do remember that the carb was the first thing to go. Then the exhaust, intake and outtake was bored out, 13 tooth sprocket in front 36 or 38 in back,head was also shaved.Keep in mind that a replacement part could be bought,or found at the dump so we could afford to exeperement. I do have a DEllorto 15 that I hope to try but it appears that a 16 or even a 17 may be better. Which manifold is better for speed,anyone know why the change in the late 70s. Thanks John p.s. always read good info.