graham I have the stiffer dual stage boyesen reeds. the technigas is torquey, that may be part of the problem. I'm waiting for the homoet 6p to get back in treats. I'll try the stock head, and a higher rpm pipe.
I was at 36 before it was ported. then bigger carb, intake, port work and milled head, and I'm tearing up to 39. (i'm not a pro, but devin who makes his living and pays his bills by building and tuning mopeds is, so I'm confident that shit aint wrong)
We took an extra cylinder (to reiterate) and tried experimenting, and got no further results. I made this thread to see if anyone else had some good ideas on how to get the rpm's higher.