I just got a long tail frame capable of holding an 18-25 horsepower engine. It's just the frame, shaft, and handle. So what I'm asking is where could I get plans to build one and what motor do you suggest? My neighbor builds racing go-kart engines so I'm going to have him tweek it up but neither of us have ever messed with mud motors before so we need somewhere to start. Motor will most likely be on a 1648 tracker.

If you have a frame, shaft, and handle, what do you need plans for? The plans help you build/design those parts...

Just need to see what size and height crankshaft you need, and get a motor that matches. Do you know what was on it before?

Well I need a prop and an engine and would like to put electric start on it whatever motor I end up gettin. He didn't know what engine was on it previously so I'm kind of just going on what he did know. And he said it could handle a 18-25 horse engine. And I've heard good things about the 23 hp mini so I thought about going with that.

Just need to find out what size shaft you have and a prop should be easy to track down. Other than that, you just need to figure out what size crankshaft you need and how tall it needs to be from the frame. Both of those things may be more flexible than I think. You mentioned a mini, is that what frame you have?

The 23 vanguards are good motors, the 25/27 kohler is a good engine also. A generac may not be bad to look into also if you don't mind possibly having to put a carb/exhaust on to it to make it run right. You can get any of those motors with electric start also.