I am brand new to this site, and I run a small fab shop. For this season, I have been running a 22HP Predator engine on a BeaverDam Mud Runner Longtail. I am pleased with the speeds (22-24MPH), but I am really wanting to change it up some. I Feel that if I were to be running a 23 copperhead, I could be bumping 30, and would like to get there in a build if possible. I have a 1536 Fisher Marine that I am using for the boat, and I am considering building a surface drive for the 22 HP Predator. I have found one really good thread by fowllife08 and his aluminum build. I was already considering building it out of aluminum for weight saving, and this looked really good. One thing that I have yet to find is someone that made one, and used a clutch. This is my biggest reason that I want to get away from a longtail. I guess my main questions are:
What clutch?
What gear ratio?
What timing belt?
What prop?
Thank you in advance for any information!

This isn't what you asked, but I'll provide some thoughts, feedback, and opinion.

I continually talk highly of the 22hp predator. It’s a great bargain and if you leave it stock should last a long time with proper maintenance. I put one on a Backwater Inc. long tail that I've since sold to a friend. It ran similar speeds to yours on a 14x42 Alweld. 22-24 solo and 19-21 (2) man hunt load. I by-passed the governor, cleaned up the intake, cleaned up the exhaust. It holds 3900ish RPM in the water.

It has approx.. 150 hours on it now, and it has had only two problems. The starter was grinding due to the bendix not fully engaging. Loosened a few bolts, realigned it and problem gone. The 2nd problem popped up last weekend and we fixed it last night. Was only running on 1 cylinder. Cause was a clogged jet. Easy fix. Still a good strong budget motor.

You can do your research on homemade mud motors. Use google to get better result, as this forms search feature isn’t that great. Add “site:mudmotortalk.com” to the end of your search.

Lots of people have made them. The homemade long tails have a higher success rate than the surface drives. A lot more math, calculations, design thought, tolerances, and alignment is involved. If adding neutral was as simple as it appears to be at first glance – everyone would have done it years ago right off the bat.

A simpler design like Go Devils would be easier to recreate. An electric clutch setup will work, but is going to take a lot more research, trial, and error.

I’m not saying it can’t be done. What I am saying is do your research. Look at a ton of photos. Learn from other peoples mistakes. Most importantly – have some patience.

Good luck!

Thanks reharbert! Definitely some good things to think about. The only issue that I have had is that it is VERY cold natured. The first cold morning I took it out (17 degrees), I sat on the boat ramp for 30 minuets fooling with it because the choke cable was froze up, and it didn't run right that whole morning. I have seen that some people use MudBuddy clutches, but I think that if you go that route, then you have to use everything mudbuddy, and I do not want to have to do that. I think I have just decided to make it similar to the copperhead, but aluminum, and possibly electric trim. Still looking at everything, but I plan on writing it all up, and taking some good pictures if, and when I do tackle it.

Throttle cables are going to freeze in general. That's not even really related to the Predator though.

It shouldn't be "cold nature" once running. Turn the idle screw in a few turns. You can adjust the idle circuit needles as well.