Posting for a friend- trying to look for the best gear ratio for his mud buddy 35. It's got heads, pistons, cam, roller rockers, mikuni and exhaust. When running a hammer or BB he's only turning around 3750 rpms. It's got 4750 coils for sure. It's getting terrible speeds @ 25 empty. He had a 40/46 gear set but now is running 38/46. Any advise on gear options would be great to get some more speed out of it.

38/50 is stock, is his boat a big fat turd? Big hook in hull or....

If he's turning the same rpms with both props, it's not the gearing that's the issue. Those props are night and day different as far as the load placed on the engine. They won't turn the same rpms unless the engine is limited somehow.

Is he getting full travel of the throttle, and is the carb clean? Sounds like it's not flowing as much as it's capable of, and the flow is limited in the same place.


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With the prop out of the water we can get it up to 4700 rpms but when WOT still only doing about 3750 with both those props. Any idea what else we could look at? Motor seems to be running good and feels strong.

Mikuni is brand new out the box so it's all clean. Throttle cable is all good as well.

Needs some carb adjustments it sounds like. Was the carb adjusted with an afr meter or by spark plug color, by ear etc. or not at all? That motor should be on the coil limiter oow in a second or two and should be on the limiter or near it in water. Is this his first mm? Dumb questions but don't know what to check if you don't ask.

As Russ mentioned I'm going to check the throttle on it this afternoon to see if it's opening fully then go from there.

Throttle is definitely adjusted properly. Slide inside the carb is fully opening. Next thing is to check the main jet in the carb tomorrow.

If you see max NO load speeds of 4750 and you are only getting 3750 in the water. I'd do a Compression and leakdown test. Check valve lash, Check for cam operation (look for flat lobes), and state of tune.