---

Update -

I built a jack plate onto our hydraulic tilt trim unit and got up to 23-24mph, 6200 rpm using an induction tach.

I bought a 9.9x13 prop which is only 1" up from the stock 9.9x12 and I can only reach 4700rpm, 22mph and that's with only me in the boat plus some gear.

Is it possible they manufactured a lower gear ratio version of this motor (it came from a big river raft)? Or is there something else that could be wrong with the set up?

AV plate is just out of the water at WOT. Carbs were cleaned recently and looked good.