I have a ys 45 with a tuned pipe and I am wondering how I go about getting it tuned right. I have enver had any expperience with tuned pipes so I dont know how to tell if it is running correctly. The header is about 6 inches long and it has a macs 8.5 tuned pipe. I ran the engine the other day and got about 11,200 rpms with an 11x7 pusher prop. is that good or does this engine perform better? I took the 11x7 off and now am going with a 10x6 prop. Any advice would be apprecciated.

Last itme I set up a tuned pipe was a while ago but the process is not going to change. Put teh full length header and pipe on your engine with the prop you intend to use and get your tach and tubing cutter. Tach your engine and then shorten your head in 1/4" increments until you see a drop in RPM at full throttle.

There is a nice write up on the proces here http://www.macspro.com/tuning.asp

Thanks