Apologies to the o/p for jumping in on his thread but when you say you are 'spinning out' does that mean you are going too fast for your legs to contribute any power as the pedals are going round so fast ?
This occurred to me a couple of weeks ago as even with my 250W motor at times it nearly does the same even when in the highest gear. In this situation is there any alternative to having to use the throttle continuously ?
The reason I'm spinning out is the gearing I could go larger on the front ring but generally I struggle on anything larger then 48t at slower speeds, so it is a compromise.
My remarks was to let potential buyers know that the motor may well and probably will go a bit faster if you have the power to surge on, esp with a 52/11t top gearing.
For my riding power level, I don't like to grind a way so prefer gearing to allow me to spin more freely. I prefer to have lower gear range I use more often rathe then high gears I use infrequently.
Down hill is no problem as gravity takes over and tend to freewheel esp when I'm at 40+ mph.