BadassbigG

I'm running an old wood Dumas Hotshot 3.5 with k&b 3.5. I've upgraded to the dubro adj. mount. The problem I have is the boat gets some speed cavitates (revs) slows almost to a stop then shoots off and repeats. I've tried adjusting the mount in every direction and it does it no matter what. The prop I beleive is the factory P215 and it looks o.k.. I am just getting into boats and would appreciate any help. Thanks.

Ron Olson

My Feedback: (1)

Start with the engine parallel to the transom and the centerline of the prop shaft slightly above the bottom of the sponsons. Make adjustments in small increments, lower if it continues to cavitate and angle it up to where you have about 4 inches or so of the sponsons in the water at speed. You'll want it high enough to where it will still turn and not fly off the water.

ryan_t888

Start with that^^

Also, some aeration of the prop is very common with any surface driven boats. If you must drop the RPM's in order for it to catch and accelerate, you may have an engine height problem.

Ryan

ob nut

My Feedback: (1)

The P215 is not the "stock" prop that comes with the motor. It is however a good prop to use with a K&B 3.5. If by chance you do have the cheap prop that is stock with this motor, toss it out. The x437, x437/3, x440 or x440/3 are good props to start out with, there are others. As with what Ron stated, that is how the motor should be lined up with the bottom of the running pads. However, I like to run my boats very loose with only about 1/4" of the pad on the water.