2 Stroke exhaust calculator

This app is simply brilliant, and brilliantly simple. I have used this app with tremendous success to design and fabricate over a dozen exhausts for both reed and piston port induction motors. I overcome the issue of not being able to work transfer timing into the design by working backwards; choose an exhaust duration that suits the rpm/target hp, then select transfer timing to suit from one of A Graham Bells graphs, adjust the ports and build the pipe. Trust me, it works!

been a while since i made a pipe but results look about as expected. no transfer timing? guess i can only try and see. any pipe is better than no pipe. have to soup the chainsaw up a bit!

Hi, i am having trouble using the calculator. No matter what i try, the calculated i.d is wrong (header pipe i.d is larger than the belly i.d, etc). Do i enter my port messurments in Millimeters or inch, etc? Engine is a "66cc" motorised bicycle engine. Cheers.