Inboard DIY race motor

[microbream]

http://www.amazon.com/dp/B0040ZWU18/...SIN=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