Balancing the props on GPengines is recommendedin most cases. However, with larger engines, especially gas, an out of balance prop can actualy be used to smooth out the performance. The counterbalance of many "adapted" chainsaw engines is never accurate otherwise the price would be more than most modellers would pay.
refer words from the old master:
Prop Balancing - Joe Wagner - March 9, 1998 .
Recommendedreferences for propellers:
Bolly Book (The) .pdf
Props, Balancing, Engine_Prop Ratio
more undersub section "Propellers" at
Alan's Hobby, Model & RC FAQ Web Links</p>
Regards
Alan T.</p>