Thanks for that! Mostly agrees with Myron's specs. Looks like they used the 2.12 atomizer in 78 and switched to 2.22 in 79/80.
I have a 2.12 with the 56 jet, so I'm pretty close. I have already modified the exhausts. I have a 2.22 atomizer I can try. Kind of odd that they went to a smaller air intake pipe on the 2hp model? Mine has a white flex pipe, but in the end is a small black disc that restricts the hole to about half or 3/4s. I though that was odd, and I removed the black restrictor. Perhaps I need to put it back according to this spec?
So last couple things to try. 1. Remove gasket (does it help much?) 2. Switch to 2.22 atomizer. 3. Go to 14mm intake (and carb? mine is a 12 currently) again does going from 12 to 14 make any significant difference?
Cool that you guys have these documents!