I'm runninng a Kohler command pro--25 hp. (CH25S) on a godevil long tail=mounted on a godevil 16x44 hull. Had carb issues, eventually changed the carb and fixed the problem--ran 18.6mph with the old carb, just me, no load---now runs 14.2mph, just me no load. Engine sounds good--but i don't have a tach yet so i'm not certain how many rpm i'm turning. Assuming the rpm are within range, what else would make it slow down? The prop is supposed to be a 9 inch diameter but it's worn down to 8.25 inches, how much would a new prop help my speed?

You do Need a new prop.. But I could almost guarantee that the new carb needs some tuning. Just wait until you get your tiny tach in and set oow rpms at 4250-4300

I never had any speeds over 20 on my old 25 kohler on go devil boat, it seemed to be a tourqe monster but not a speed demon . You should be running a 9 x6 wheel on that . Call backwater and save some money for your new prop .
Good luck

H Finn

I run 18mph with a light load with just me on a 1542. My prop is only worn about 1/4". Godevil told me once I get to 8" replace.

The BH2O props will work on the GD? What's the advantage speed or torque? proof?

If I could get 20mph out of her I'd be very happy--I agree about the speed/torque on the kohler engine, she's never gonna be a speed demon, but that's OK with me. GoDevil recomends prop replacement when it's worn 1 inch--it has a 9x6 on it, but it's only 8.25x6 now!! I've been thinking of replacing but wanted the other problem fixed first. Ordered the tach--should be here Monday or Tuesday.

Props---Back water and Hill Marine both sell new on EBay, prices are the same and very reasonable. and about $100 cheaper than new from GD.

Tach installed--she was turning 3680 at most. Turned her up to 4000 OOW and she sounds like she's gonna fly off with the boat and trailer! Gonna test run it this weekend and see how the speed goes. Wish me luck!!!

sj

You should be able to see at least 20 out of it depending on your boat. I got 22-23 empty with a fresh prop. 21-22 probably more average. 19-20 with two people. 18-20 2 people dog plus all hunting gear and 3 doz weighted keel deeks.

Curious to where you got your tach, how you turned up your RPMs (assuming you adjusted the governor ) and did doing that effect your idle? Also what is safe RPM for these motors?

Bought the tach on eBay. It's a knockoff tiny tach. At 4000 rpm oow-it turned just over 3000 in the water. Got 18mph by gps-turned it up a little more-started out great then started to lose rpm and slow down. Throttle wide open. Back to 14mph and a max rpm just under 2700. Shut it down to adjust the throttle cable some and it ran for 20 seconds or so after I turned off the key. Never done that before-and then it wouldn't start. Paddled back to the ramp. 2 hours later in the yard at home it started right up and went to 4000rpm. I'm thinking the spark advance is bad. Ordered a new one last night.

And yes I used the governor to adjust the rpm. Just turn the screw clock wise on the throttle plate. And it did affect the idle speed-but it's not supposed to.

I get 21mph out of my 25 kohler at 4100rpm on a 1448 all welded crawfish skiff and thats with two people

Got 17.9 today with me and the gas tank. It's a 16x44 go devil hull. Engine turning about 3400 max with the prop in the water.