For my opinion Saito 82 is much better then Yamada 63. The best power/weight ratio from all listed engine, + Saito little more simple in adjustment (especially in winter conditions) In anyway Saito 72 or 82 (80 is too heavy). About vibration: in well adjustment Saito work more “soft”. About fuel: Yamada need “Yamada Blend” (20% synt. Oil + 20% nitro). Saito well run on all 4-cycle from 5% to 30% (I like 15% CoolPower).
Pavel