I recently purchased my first mud motor and boat. A 14'6" x 48" aluminum boat (15" transom). the boat is powered by a 23hp Vangauard Go Devil surface drive.

Currently, spinning a 9x4 prop at 2800-3000 for 13-14mph with 2 adults, 5 gal fuel (in the back), 2 12 volt batteries. Is this considered normal?

To me, the motor seems like is has more to give but just not getting there on the RPMs. I have been through the carb a couple times, motor has 150 psi in each cylinder, new fuel pump, new spark plugs, new in line fuel filter, and new gas. Motor will run up to 3900 rpms out of the water and up to 4300 rpms if I hold the governor with my fingers.

I have read many posts about motors bogging down in the water and there are so many possible cures, just thinking that I should not be losing 1,000 rpm in the water. If not normal, thoughts on improving the RPMs.

Here is a pic of the rig.
IMG_1237.JPG

You said surface drive, but the pic is a longtail?

You should be getting more RPMs than that in the water. May need to tinker with the linkage to get more throttle travel. What's your idle at? Is the throttle assembly been messed with/cable shortened?

Every used longtail I have ever bought needed throttle adjustments.

oh yeah you are right - just re-read my post. it is a long tail.

i looked at the linkage. while it looks standard to me, i suppose it could have been shortened. how would I be able to tell if it is shortened? I do know that when the throttle lever is at 3/4 the actual throttle is already fully engaged and the remaining travel in the lever just bends the stiff wire going to carb.

Out of water wide open you should be on limiter, so id adjust the throttle.