RPM with the 19x11 or 20x10.5 is around 7600 when the engine is new, so during break in the engine performs as a broken in 170, actually you can go directly to 20x10.5 on break in.

As Don mentioned above, this engine is the best running YS yet, extremely easy to set, and the vibration at idle seems to be half of the 170.

Yamada told me APC was working an a new prop for it, 21x10 I think it was, but not 100% sure, time will tell.

Regards

Alejandro P.