I have 1640 aluminum boat that I am thinking about turning into a duck/fishing boat. It currently has a '78 Mercury 500 (50hp) on it that needs a little work done to it. I've been looking around at options and thought about building a MM.

I have a motor from a racing fourwheeler laying around, and I need to know if it is a plausible idea. It's from a '87 Kawasaki Tecate 4. Stock it is a 250 2 stroke, but mine has some work already done to it. I would say it is an easy 40hp at the rear wheel possibly up to 60hp. I'm not sure what size motor kit is in it since I haven't opened it up personally, but I was told it has a 315 stroker kit in it.

I really like the idea of keeping the console as well and figuring something else out for trimming the motor. Between me and a couple of friends, I have no doubt that we can get the fabrication done.

I'm thinking of a hot foot with a hand shifter for gears. If the gears don't work out, I can always set it up to turn whatever RPM I need in one gear and never shift. Short tail styled with a chain under the cover which would allow for even more gearing options. Any opinions or comments are welcome. I plan to do some more research before building anything, but I would like to find out if it is a waste of time before I get too deep.

i have had the same idea. just wondering about shifting gears?( its the reason i've never tried it). i've never seen a boat with a tranny, try it and let me know if it works

i've often wondered why nobody uses and atv/snowmobile type cvt transmission. seems to make sense to me. there is no switching gears (which would be tough in a boat) and the clutch is designed to keep the motor in its optimal rpm range at any given wheel (or prop) speed. Many also offer High gear, low gear, and reverse. Ive done quite a bit of work and mods to the clutch on my 4wheeler. there are so many options with regard to tuning those things. You would definately have to keep it completely sealed but that shouldnt be a problem. Maybe i'm missing something.

maybe LJHOPP will chime in

The boy's a genius!!!

When we gonna see the 2011 model line up of your design.

As far as a gear box, the motor has a transmission in the case with forward gears and neutral but no reverse. I'm not too worried about reverse, though, at least not for now. What are the advantages of belt drive systems over a chain with a tensioner? I was planning on chain since it is already set up for sprockets, but I can get belt pulleys machined if it is that much more beneficial.

As far as shifting gears, I was planning on using a racing shifter. Lever on the handle for the clutch, forward to shift one way, backwards to shift another. Cables run from the shifter to the motor mount where it pulls on the respective side of a custom shift lever to shift up or down. I'm not even sure that shifting will be a good idea, but I can leave it in one gear if shifting doesn't work out.

i thought about the center dif from a golf cart. small unit that has f-n-r. they can take a bit of hp. they aare running the same motors.

difference between the belt and the chain is once u hit a stump the belt will give, i dont see the chain giving to much but i could be wrong

Here was my attempt with a Comet 94c cvt clutch and a 24 Honda. I am no fitter and not the best welder, and no machine shop, so please ignore the bad welds and etc........... Anyways it did shift gears, but takes alot of fine tuning, I got a top speed of 28 mph gps on a 1542 flat. I currently have 24 Honda on a Mud Buddy mini frame, which I made an awesome deal on. I also built a 6.5 with a 20 series cvt , it is turning a regular longtail 9x7 hill marine prop, it makes 14.9 mph with 2 on a 1436, it is one year old and still working. Cvt does work, it is a low gear when you are at low rpm's and when higher rpms a higher gear. When motor gets in a bind, rpm get low and cvt goes to lower gear. What made me curious is my kids have a cvt chinese 80cc fourwheller and man they ran the crap outta that for 4 years and it is still going strong. So IMO if someone with more fitting and fine tuning skills than myself attempts this, it would work very well.

Pretty neat...

nice. I new a cvt would work. Seems like the way to go to me.