Just a question for the experts, I know that the operating range of surface drive type engines can run anywhere from 3600-4600, but what is the best rpm range for the surface drive prop? Obviously, our props are not seeing this engine rpm but less because of the various gear reduction ratios. My homebuilt 6.5hp surface drive engine runs approx 3600 and at 1.63:1 ratio my prop rpm is only about 2254. Anybody have any thoughts on this. My current prop size is 9x8 hill marine on a 14x36 jon boat.

Gotcha, thanks for the response. On another note while out fishing the other day I reached back and grabbed the governor, took the motor rpms up between 4300-4600. I picked up a couple miles per hr and it was not until I hit these rpms that I got the classic rooster tail surface drives are known for.

Adjust your throttle so you are seeing 4100 to 4200 out of the water. When you are running and get up on plane, trim so that your prop is about half in the water. This will help you with performance and help you see that typical surface piercing prop rooster tail.

Mag10

Thanks Mag 10 I will give that a shot. How is the duromax build coming along?

just doing the final assembly. Should have some pics to post this week

Well I for one believe that 1.6 to 1 is to high. I thought that the optimum ratio was in the 1.2 to 1 range.