I recently aquired a Honda express that had been sitting since 1988, and I got it fired up and put a few miles on it, but the top end let go so I decided to go with a 73cc top end with Boyesen 2 stage reeds, Proma pipe I modified, and last but not least a Mikuni VM20 Carburetor. I've got it running and took it out for a spin with the stock jets (22.5 idle, and 180 main)
It has trouble getting up to speed from a dead stop. Really sluggish. But then when it starts going the powerband will hit and launch to 45 mph no problem. Then after that it it falls on its face. If you try to cruise at half throttle it will cough and choke. Checked the Spark plug, it's dark grey.
I know A lot of people ask jetting questions and I've searched the whole website but cannot find a straight answer
I want to get a good idea of the jet sizes I should be getting before I drop too much $$$ in jets I don't need. From what my motor runs like, I should bump down the idle jet size and bump up the main jet size? Am I on the right track? Or maybe c-clip on the needle and slide if there is one?