Inboard DIY race motor

[microbream]

Hi Guys,
I enjoyed Ron's DIY outboard race motor and it got me thinking?
How about using the same ohv 4 stroke motor and mounting it inboard?
connecting straight to the prop shaft via a auto cv joint should do the trick.should be both lighter and more efficient.
Or to go realy balistic how about a air cooled 250cc MX engine and gearbox!
now that would be interesting.
has anybody tried something like this?
cheers
Kael

[Skoontz]

Have plans for a 12' cracker box type boat that I wanted to power with a 600cc Suzuki Katona motor turned sideways. I put a lot of thought into a smaller inboard, and felt the weight ratio to power drained from the driveshaft would have to balance out around the 600cc/80 HP mark, and depending on propeller selection, you got a redline at 12,500. Just hook the driveshaft to the tranny and you got 6 ratios in which to play, and you can even use the factory instrument cluster.
Its been years since I played with any lawn mower engine type performance, but the amount of fiddling needed when we ran them on mini bikes was extensive, and hop up parts had to me made. With a motorcycle engine, you can buy a great deal of the stuff already made!
Now that I've been accepted as a volunteer at the Lake Tahoe Maritime museum at the restoration projects facility in Truckee, they will let me use the space to build the boat....But then there is the time...I've only budgeted a day a week to volunteer and all else taken with projects. Keep us posted about what engine you may want to use and your project.

[Fastjeff57]

There's a U Tube video out there of a guy who put an inboard prop setup on his jetski. Close enough. But I got to tell you about the paddleboat racers of western Kentucky.

If you're thinking "Delta Queen" of those little peddle cars, forgetabouit! We're talking full out BEASTS with really simple class rules: The boat must be propelled by a paddlewheel. Period!

A typical entry was my buddy's, powered by a Honda Gullwing MC engine connected to the paddlewheel. He starts off in LOW gear, then upshifts after the boat's on plane until he hits 5th or 6th at the turning pylon, then downshifts a few gears to get moving again. Far out, eh?

Well, that's nothing compared to the Rainmaker! S B Chevy powered (through a Powerglide, as I recall) to an astonishly fast spinning paddlewheel. Down the straights at 60 mph, throwing a rooster tail a hundred feet high! Whoopppee!

Jeff

[microbream]

Have plans for a 12' cracker box type boat that I wanted to power with a 600cc Suzuki Katona motor turned sideways. I put a lot of thought into a smaller inboard, and felt the weight ratio to power drained from the driveshaft would have to balance out around the 600cc/80 HP mark, and depending on propeller selection, you got a redline at 12,500. Just hook the driveshaft to the tranny and you got 6 ratios in which to play, and you can even use the factory instrument cluster.
Its been years since I played with any lawn mower engine type performance, but the amount of fiddling needed when we ran them on mini bikes was extensive, and hop up parts had to me made. With a motorcycle engine, you can buy a great deal of the stuff already made!
Now that I've been accepted as a volunteer at the Lake Tahoe Maritime museum at the restoration projects facility in Truckee, they will let me use the space to build the boat....But then there is the time...I've only budgeted a day a week to volunteer and all else taken with projects. Keep us posted about what engine you may want to use and your project.

That sounds great, have you thought about a jet ski engine? I think the biggest problem with motocycle engines is lack of torque, even if you used a gearbox i think the boat would would slow down too much between gear changes.
will you run a cleaver prop and what angle would your propshaft be?
i have done some more research for my project and a briggs and stratton world formula go cart race engine has 15hp and weights just 15kg.
will run up to 7000rpm . Obviously hop up parts are every where. Another option is a subaru kx21 race engine.
Both are 200cc single cylinder air cooled 4 stroke ohv. My hull will be a 10ft aluminum jon boat .
cheers kael

[microbream]

There's a U Tube video out there of a guy who put an inboard prop setup on his jetski. Close enough. But I got to tell you about the paddleboat racers of western Kentucky.

If you're thinking "Delta Queen" of those little peddle cars, forgetabouit! We're talking full out BEASTS with really simple class rules: The boat must be propelled by a paddlewheel. Period!

A typical entry was my buddy's, powered by a Honda Gullwing MC engine connected to the paddlewheel. He starts off in LOW gear, then upshifts after the boat's on plane until he hits 5th or 6th at the turning pylon, then downshifts a few gears to get moving again. Far out, eh?

Well, that's nothing compared to the Rainmaker! S B Chevy powered (through a Powerglide, as I recall) to an astonishly fast spinning paddlewheel. Down the straights at 60 mph, throwing a rooster tail a hundred feet high! Whoopppee!

Jeff

Wow i have gotta see that!!!!!!

[Skoontz]

I dont think the torque will come in to play as much as if the size is there. More size is more torque. The thought behind motorcycle engines is that stuff is available with about any hop up bolt on you can find for dirt cheap. Lots of crotch rocketeers find their ways around trees and guard rails with very low milage on the motors, where a jet ski engine by the time you find something cheap enough is going to be plain worn out. But we can bench test this stuff all we want. My grandfather had a plaque on his test tank that bore this inscription. "One test is worth 1000 expert opinions"

[microbream]

I dont think the torque will come in to play as much as if the size is there. More size is more torque. The thought behind motorcycle engines is that stuff is available with about any hop up bolt on you can find for dirt cheap. Lots of crotch rocketeers find their ways around trees and guard rails with very low milage on the motors, where a jet ski engine by the time you find something cheap enough is going to be plain worn out. But we can bench test this stuff all we want. My grandfather had a plaque on his test tank that bore this inscription. "One test is worth 1000 expert opinions"

yes there is no substitute for cubes at the end of the day.
makes me think about using a 250cc mx engine 40+hp and six speeds !

[stupidbaker57]

I'm using a 400 Honda automatic engine in an inboard surface drive of my design. The boat is a 3 point hydro that is 11 feet long. Not done building it yet (almost tho) I got the engine running while it's bolted into the cradle that will be mounted in the rear of the boat.

[microbream]

I'm using a 400 Honda automatic engine in an inboard surface drive of my design. The boat is a 3 point hydro that is 11 feet long. Not done building it yet (almost tho) I got the engine running while it's bolted into the cradle that will be mounted in the rear of the boat.

are you running it though an auto gearbox or just direct 1:1 ?
what angle does you propshaft run at? have you tilted the engine or used a universal joint.

cheers
kael

[Ron Hill]

http://www.amazon.com/dp/B0040ZWU18/ref=asc_df_B0040ZWU181766162?smid=A18F233SN21KKY&tag=nextagusmp0404107-20&linkCode=asn&creative=395105&creativeASIN=B0040ZWU18

This is my next DIY Outboard Motor. It is 414 CC, 16 HP with electric starter. Two year unconditional guarantee. for $299.


I had not thought about an inboard because I'm an outboarder..

Anyone wanting to fool with an inboard, I will make props for free.

What boat style are you thinkng...

[microbream]

http://www.amazon.com/dp/B0040ZWU18/ref=asc_df_B0040ZWU181766162?smid=A18F233SN21KKY&tag=nextagusmp0404107-20&linkCode=asn&creative=395105&creativeASIN=B0040ZWU18

This is my next DIY Outboard Motor. It is 414 CC, 16 HP with electric starter. Two year unconditional guarantee. for $299.


I had not thought about an inboard because I'm an outboarder..

Anyone wanting to fool with an inboard, I will make props for free.

What boat style are you thinkng...

10foot aluminium jon boat! yes certainly no race hull but a super fast fishing hull!
weight is important as although i live 5mins from a river, there aint no boat ramp.
Thus i have to carry both boat and motor to the water. If i built a DIY outboard with say a 200cc go cart race engine, i should be able to get 15hp out of 20 ish kg.
have you run you design yet? what size prop shaft do you recomend, and what bearings did you use?
there is also the option of using a vertical shaft motor and conecting straight to an old outboard gear case.

[stupidbaker57]

The engine is in sideways with a chain coupler driving a jack shaft to another short chain driving the prop shaft. This way the engine can be mounted in the middle of the boat. The shaft runs at 7 to 15 degees. The engine and prop shaft are mounted as a see saw so that trim can be adjusted exactly. The engine is on the same 7 to 15 degree angle.

There;s a set of plans called "El Cid" that is a small hydro that uses a four stroke for an inboard.

[MercManEC]

ive been looking into something like this for years now.... never even saw this boat before but im definately building one now...i have a twin cylinder 18hp briggs thatll go good on it or maybe a 250cc dirtbike motor....where do you buy a shaft and such for something like this? out of my zone with this ive never had anything inboard before...

[stupidbaker57]

I built my own shaft and tube. For my prototype I used (get this) 1 1/2 exhaust pipe that I expanded to 2 in id to fit the bearings. 1 tapered bearing on the prop end for thrust, and a sealed ball bearing on the top. Double seals on the prop end. I used a 3/4 SS shaft machined to fit one of Ron's props. If you use this design could work for a low HP engine in the conventional position under the boat, you wouldn't need a stuffing tube.

[sharpeye Mike]

Have you thought about building a mud motor instead, those are sweet to.

[MercManEC]

I built my own shaft and tube. For my prototype I used (get this) 1 1/2 exhaust pipe that I expanded to 2 in id to fit the bearings. 1 tapered bearing on the prop end for thrust, and a sealed ball bearing on the top. Double seals on the prop end. I used a 3/4 SS shaft machined to fit one of Ron's props. If you use this design could work for a low HP engine in the conventional position under the boat, you wouldn't need a stuffing tube.

yah i had something like that in my head.your idea sounds alot better than mine though haha...i was thinking a bronze tube around the shaft with o-rings and have a zirk fitting to fill the tube with blue grease.(not sure it would last to long)..i would like to use my opposed twin 18hp briggs and run the exhaust out the back and do it half and half under water and above water like a chris craft so it sounds pretty cool..i wonder if a snowmobile engine would work...those things are pretty powerfull and like to wind right up there.. what pitch are you planning to run?

[stupidbaker57]

To me, bronze costs too much. Exhaust pipe is plentful and cheap. If all works out with my prototype, I will make the next tube from aluminum. O rings won;t last too long at all, and may cause the shaft to ossilate in the tube. There also is no thrust bearing. I am useing "smurf poop" for grease for the lower bearing. The upper is sealed. If your interested in building something for your twin, I can sketch out a diagram to help you.
I was going to use a snowmobile engine untill I got a deal on a 400 automatic motorcycle ($60)
I have a Ron Hill 7 X 12 cleaver. The bike is direct drive to a jack shaft then it changes to a 16/21 ratio