Honda 5 HP with threaded shaft - need clutch

[ahickman]

I have a Honda 5 HP horizontal that I want to put on a kart body. After removing the pump plates, I found that it was not keyed, but was threaded. Kind of a bummer. What options as far as clutches do I have? I was hoping to use a simple centrifugal clutch ($50) with keyed shaft.

Aaron

 

[r_chez_08]

Any pics?

 

[Bluethunder3320]

you mean a tapered shaft?

best option IMO is go get a honda gx160 (is it?) or in that case, clone crankshaft.

 

[ahickman]

Do you mean, replace the crank with a new one?

 

[anderkart]

I have a Honda 5 HP horizontal that I want to put on a kart body. After removing the pump plates, I found that it was not keyed, but was threaded. Kind of a bummer. What options as far as clutches do I have? I was hoping to use a simple centrifugal clutch ($50) with keyed shaft.

Aaron

Pics would really help us to help you, but:

If your current output shaft is long enough, and also a large enough diameter, you could probably machine it down to a standard 3/4" diameter, and broach/cut in a keyway, so you could install a standard 3/4" bore centrifugal clutch and key.

Then you wouldnt necessarily have to drill and tap the end of the crank if you bought a clutch that was equipped with set-screws to hold the clutch on.

But if you have to pay a machine shop to have this done, It might end up costing less to simply replace the crank or maybe even buy a different engine.


How long is your engines output shaft?
And what diameter is it?
Does it taper down from large to smaller at the end?

 

[ahickman]

It took me a while (too many projects), but here is a picture of the shaft. The model is a GX160-163.

 

[anderkart]

The simple fact that your output shaft has external threads at the end may not be big problem for mounting a clutch.

However, your output shaft must have a keyway machined in, and be a commonly used 3/4" 5/8" or 1" diameter to buy a clutch that will fit and work correctly.

Does your output shaft have a keyway/slot machined in like the left end of this picture below?

Does it gradually taper down to a smaller diameter near the end before the treads?

Also, what diameter and length is your engines output shaft?

 

[ahickman]

No keyways on the shaft. The last 1" is threaded, where the diameter is less than the 3/4" original but only owing to the pitch of the thread. I guess my options are replacing the shaft ($100) or having the keyway machined ($??).

 

[r_chez_08]

http://item.mobileweb.ebay.com/view...escription&index=0&nav=SEARCH&nid=34005544711
This one is a lot less than $100 and comes with a spare piston/rod
Rob

 

[anderkart]

No keyways on the shaft. The last 1" is threaded, where the diameter is less than the 3/4" original but only owing to the pitch of the thread. I guess my options are replacing the shaft ($100) or having the keyway machined ($??).

Yep, you could call and ask some machine shops how much they would charge to "Broach a keyway" into your crank. Tell them your 3/4" bore clutch has a 3/16" key, so your cranks keyway would need to be 3/16" wide, and 3/32" deep.

They will most likely want you to remove the crank, but ask anyway.
If you decide to get it done, I'd buy a clutch first and bring it along so they could test-fit it.

I've never seen this done, but you could probably just use a nut/washer(s) on your crank to hold the clutch on,
OR some clutch models are equipped with set/grub screws you can tighten down to lock the clutch to the crank.

 

[r_chez_08]

I've never seen this done, but you could probably just use a nut/washer(s) on your crank to hold the clutch on,
OR some clutch models are equipped with set/grub screws you can tighten down to lock the clutch to the crank.

i wouldnt reccomend that because i think enough torque will go through the shaft to make it slip. however i guess you might be able to get a big nut on that shaft tighter than a little bolt...

 

[anderkart]

i wouldnt reccomend that because i think enough torque will go through the shaft to make it slip. however i guess you might be able to get a big nut on that shaft tighter than a little bolt...

I just meant after the OP had a machine shop broach a keyway into his crank, he might be able to hold the clutch on that way. (instead of him paying more to drill/tap internal threads into the end of his pto...)

 

[r_chez_08]

Got ya! Yeah that would make sense, because knowing machining prices they would probably add $10 to drill and tap.
Rob

 

[webrx]

couldn't you just use a dremel to cut or grind a keyway in the shaft? seems like this would be feasible, install the centrifigul clutch, and use washers on the inside and a nut and washers on the outside to ensure alignment with the sprocket. This might be cheaper than a shop, though you would need to be careful or you would be buying that new shaft.

d

 

[r_chez_08]

I think you could possibly rough out a keyway with a dremel, but you need the keyway accurate otherwise your clutch will wobble, causing wear on both the shaft and the clutch.
Rob

 

[anderkart]

couldn't you just use a dremel to cut or grind a keyway in the shaft?

Yes, some people have the skills, knowledge and patience to correctly do this.
Most other guys would either f**k up their crank or hurt themselves. (or both

 

[ahickman]

I think replacing the crank with a keyed version is going to be easier. Thanks for the input and ideas.