Umm where did I say it was a standard springer?
No, this is me, I don't do standard, instead of these weedy little 14" x 9" things I do 24" x 15", power is a starter motor and two 12v 7ah, possibly larger SLA's
70mm is a guess, but due to the fact this motor has about the same torque as a DesertAircraft 50cc engine, it probably needs to be bigger than that....
Also, anyone know how many amps a starter motor draws? It's just a standard HiTork starter motor
So far I've made the hull, Glassed it this morning and painted the undersides this afternoon.