Clutch for 20hp engine!

[smooth90]

I just picked up a p220g Onan engine from a friend for $100. It has been stored for years but still runs.

The engine specs are as follows

V Twin Engine
Displacement 782cc
Horse power - 20hp
Output shaft - 1.44in

I have no idea why its 1.44in but I think that I can shim a 1.5in sprocket/clutch on with spring steel strips.


I would like to use this monster in a big go kart or a really overpowered mini bike.

The biggest problem is that I CANNOT FIND A CLUTCH!!!

Where do I get a clutch for a 20hp motor and 1.5in shaft! All of the go kart clutches stop at about 13hp and 1in shaft. I can deal with the shaft size problem by using a jackshaft but using a 13hp clutch on a 20hp motor probably won't end well.

Can anyone help point me in the right direction here.

-Thanks

 

[kendelrk]

go to a junkyard, and look at some older biggg tractors, and look for a 20hp engine,or call your local mower shop

 

[tatakart]

trade me your engine for my honda 5.5hp. let me go through all the trouble and you can use my mega engine quicker than having to buy things and getting them shipped. Great deal for you, more trouble for me ! agree??

 

[r97]

You have 3 common options.

1. buying a noram 1800 series centrifugal clutch, http://www.noramclutch.com/centrifugal-clutch/1800.html

2. buying a comet 40/44 series torque converter (this is an automatic transmission, giving you several ratios, unlike most other options which have only a single gear ratio).

3. belt tensioner, this is by far the simplest, and could be setup to be a multiple speed system. unlike the other two options, this setup is not automatic, but is the cheapest.

If i were building something with that engine, i would either use a 40 series if i had the $$$, or make a belt tensioner. the centrifugal clutch is almost as expensive as the torque converter, which is a much better system.

 

[the-cyborg]

I'd say take the crank out take it to a machine shop have the turn it down to 1" mill 1/4" keyway.
buy a 40 series torque converter setup and give her h3ll.
Now 20hp on a minibike ? are you crazy or just have a death wish, that thing would be extremely unstable at best.
20hp does not mean it will be faster just means it will have enough torque to haul a sumo wrestler, or pull stumps. and will be extremely heavy, I'm guessing around 50-60 lbs
Now on a good size buggy, yes I could see that, but not a minibike or a smaller kart, it would be way overkill and the power to weight ratio just means you'll burn more fuel hauling it's self around than it's worth, when you could get the same speed from a 5 to 6.5hp engine that is much smaller and weighs half as much. unless of course you are a sumo wrestler, or in the stump pulling business then disregard this post.

 

[smooth90]

Well when I say minibike I'm thinking of a rather large framed setup. It would be wide to accommodate the engine and long to offset the center of gravity (avoid popping wheelies). I would set it up to do a max of 30 but what I really want is that MASSIVE amount of torque going to the wheels. This is also a V twin engine so at low speeds this thing will crank out more torque than a 20hp motor of a different design. I want to be able to accelerate very quickly not necessarily reach a very high top speed. That is exactly what this engine can do.


The belt tensioner system sounds very cheap but the more I think about it the more I see that each part adds extra work and cost.

I am not to keen on the torque converter setup but that noram 1800 clutch looks really nice. I will have to see if my friends want to help build this thing as $400 for a clutch is obscene.

I'm not going to do anything for a few weeks except get the engine cleaned up and sand blast the surface rust off a few parts.

 

[anderkart]

The Noram 1800 is only available in 1" or 1-1/8" bore, not 1-1/2". Its also a belt clutch model, not chain.

I've never seen any 40-series Torque converters made to fit a 1-1/2" output shaft either.

You could mount this clutch: http://www.out2win.com/catalog/noram_enf.html on the output side of a 1" jackshaft. The Enforcer clutch model is commonly used on 4-cycle racekarts with 40+ hp engines.

Or If you dont wanna mess with installing a jackshaft, turning your engines output shaft down to 1" would probably be a good solution, what size bolt hole is tapped into the very end of your crank? Is it a 3/8 or 7/16"?