zwebx ... A note from Quenton on what size sprocket is required with the Q-matic - "Primary is 2.76 X 1 and requires a 56 tooth or larger to maintain a good over all ratio [15.45 X 1]. Smaller than a 56 tooth won't work."
Wolfie ... I talked to Quenton earlier and he said that he has an adapter that will fit the tapered shaft. Quenton said, "The Q-Matic will fit the HS 142F [5/8" shaft], Honda GXH50, HF 79 CC, and the HF 99 CC motors. They are currently offering the Q-Matic with a custom crankshaft adapter to fit the HS 142 with the tapered shaft. The adapters are currently made per order and normally requires a week to complete as they aren't a current production item.
Dan