1.125 tapered crank question

[kc9ljo]

My buddy has this Kawasaki liquid cooled V-twin. I think it's some sort of industrial engine. Anyway he wants to put it on a kart he's building, but it has a 1.125 crank and it tapers down to about .875 on the end. I can't find much info at all on this engine or a crank like this. Does anyone know where he can get some sort of clutch for this that will work for a kart?
Thanks

 

[anderkart]

I've got a huge go kart racing clutch made for a 1-1/4" output shaft engine. But Its made for an engine that has a non-tapered output shaft with a keyway machined in.

Can you post a pic of the output shaft on your buddy's engine?.

 

[kc9ljo]

I don't have the engine here, but next time I see it I'll take a pic.

 

[anderkart]

Cool, also measure how long of the crank remains at 1.125', before it starts tapering down smaller.

 

[kc9ljo]

I had my buddy take these pics. I think his techneque with the caliper is a bit off. I measured the OD the other day and it IS 1.125. But the rest is close enough for what we're trying to do here.

 

[anderkart]

Sorry, but its not looking very good.

You only have 1.353" of usable 1-1/4" diameter output shaft length, and there's no keyway machined in.

The 1-1/4" bore clutch I have needs 2-1/2" of output shaft length, and It absolutely has to use a 1/4" key to lock it to the output shafts keyway or it would just free spin and not drive the kart.

So even if you had a keyway machined in, my clutch would be too thick to fit on your crank.

What did that engine used to be on? Generator maybe?

Maybe you could find a big snowmobile torque converter driver that had the same bore/taper to fit on there... Is that a threaded bolt hole at the end of your PTO?

 

[r_chez_08]

Umm hate to tell you ander, 1.125"=1 1/8"
I was thinking machine the shaft down to 1", and part off the remaining length. Would it then be long enough? If not you could machine the entire shaft to 3/4" and cut a keyway, or build the shaft up with weld and machine to 1".
Do you have access to a lathe or a machine shop?
Rob

 

[kc9ljo]

r chez 08,
Actually I have a lathe and mill in my garage. I mentioned to him that I could turn it down for him, but he really does not want to take it apart. But that might end up being the onlt option. I'm thinkinng about making a sleeve with an internal taper that matches the shaft, and it would be 1.125 on the OD. But ever if I can make somthing like that work, we still would need to find a clutch with a 1.125 bore. So I guess we'll see.
@ ander, does your clutch have a 1 1/8, or 1 1/4 in bore?
thanks

 

[r_chez_08]

what sort of budget does your buddy have? if quite high i would reccomend spending $300 on a comet 40 series torque converter with a 1" bore, and machine the shaft down, as using a 1/4" mill cutter would be the easiest way of cutting the key anyway. also any idea of the hp of the engine, and the kind of terrain that your mate wants to ride on?

 

[anderkart]

Yeah thanks chez

My used clutch is made for a 1-1/4" pto. The drum has a needle bearing that rides directly on the pto. The key in my clutch hub is permanently attached, not a separate key. So there's no easy way to fudge things and use it on a 1.125 output shaft.

Besides that, unfortunately this used clutch I have is also a 20-tooth/#35-chain model, so even if it fit your pto, you would still probably need a jackshaft to end up with some reasonable gearing...

Another more realistic solution you could consider here is: Just doing whatever machining necessary to simply mount a solid drive gear on the engines crank, and then locate a heavy-duty centrifugal clutch on a jackshafts output side... Like the pic at the bottom of this page illustrates.

To choose a centrifugal clutch model strong enough to survive, and gear tooth counts for everything:

You'd need to confirm the H/P of that engine,
and post the karts rear tire diameter,
and post the kart and driver (passengers?) approx weight.
and post what type of driving conditions the kart will be used for.
(like maybe all serious off-road/steep hill climbing in the sand/mud
or maybe all high speed cruising on large open/flat/hard packed terrain,
or paved streets/parking lots as an example)


Here's a link to a jackshaft gearing calculator: http://www.compgoparts.com/TechnicalResources/JackshaftRatioCalculator.asp

Here's a search link to the 1" bore "Noram Star" race clutch model that I use on both of my racekarts and highly recommend: http://www.google.com/search?q=Nora...osoft:en-us:IE-Address&ie=&oe=&rlz=1I7GZAZ_en

If you could turn his pto down to 1" and broach a keyway you could just mount a clutch on the engine and skip using a jackshaft.
Here's a pic of my Star clutch: (its a big-ol heavy duty mutha !!!)

You wont find any publish max-H/P ratings for the Noram Star clutch model, but both of my Star clutches have survived my 20+H/P racekart engines for a couple years now with some very hard use. You'll also find a Bunch of guys over on a Mower-racer forum called "heymow.com" that use and recommend this very same clutch model with up to 45-H/P engines!!!

You would simply need to install a 1" diameter jackshaft with a 1/4" keyway and threaded bolt-hole in the end of the output side to use/retain a Star clutch. The Star clutch is available in your choice of 13 through 18 tooth models, but only comes in a #35 chain pitch. It can be mounted with its drive gear inboard or outboard.

If you will be running a #40/41 rear sprocket, the 1" bore Noram 1600-series model might be another option to consider: http://www.google.com/search?source...&rlz=1T4GZAZ_enUS369US369&q=Noram+1600+clutch

 

[kc9ljo]

ander,
That's a great idea. I think that's going to work. I'll keep you posted.

Thanks