Dont know if this belongs here in old school, but since its for my '67 YL2, I figured this was as good a place as any. Little background. P.O.J. was my first ever motorcycle. Found it in a grain bin about 15 years ago. Finally got around to getting it road worthy for the first time ever last summer. Been puttering with it ever since. I needed something to do (yeah, right) and wanted to work on my welding / sheet metals skills and figured this would be a good project. My first attempt came out so-so. I used a free internet program to come up with the sizes for everything after I "blueprinted" my engine. Turned out like this: While it worked okay and I learned a ton about cones, oxy/acet welding, and expansion chambers, it wasnt all that great. I had a TON of power at a VERY high rpm, but it couldnt get to that high rpm in the top gear. So, here we are at the second attempt!