Prop

[Nasty]

I have a Yam 150 2-stroke turning a powertech 3-blade 15.25 x 19. My blazer bay 1960 hits 49-51 at wot (5500 rpms) while loaded. I don't think the 4-stroker can spin the bigger diameter prop like a 2-stroke can. So my guess is trying a 14 x 19 or 14 x 17 prop. I called the powertech people. They helped me narrow down my choice of prop. I got it right the first time. They were very helpful.