My question is simply.. is it possible to mess up the timing on the powervalve, and would this result in massive loss of torque in the bottom end?
The answer is YES. Before the days of powervalves, 2 stroke engines were limited to making big power in a narrow rpm range. The powervalves essentially make it like you have one cylinder for low rpm and one cylinder for high rpm. If, for instance, your valves are stuck open, then high rpm is were your cylinder makes the most power---and the opposite is also true. I would double check the installation/function first. :cool: