Attaching clutch to crankshaft


Old 10-12-07, 06:01 PM
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Join Date: Oct 2007
Posts: 2
Attaching clutch to crankshaft

Hello all:

I have a somewhat general question applying to all (most? Perhaps non-keyed only) small engines. For a while now I've been researching small engines, looking for some little projects to do (who doesn't want to motorize something?!) and I've hit upon the idea of putting a small engine on a kick scooter. I've been looking at plans for chain drived version, but I've hit upon a little issue. Without a clutch, the wheel would keep turning unless I killed the engine, and that's not something I want. Unless I can find a small engine (2 HP range, perhaps? Anybody done something like this?) that comes with a clutch attached as well as, ideally, some gear reduction (I've heard of these little guys not having enough torque) I'll have to stick with an aftermarket clutch, perhaps the 3/4" crankshaft one supplied by Jack's Small Engines. Is crankshaft welding a DIYable job? If so, any tips?

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Old 10-12-07, 10:13 PM
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Join Date: Oct 2007
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Sorry for douple posting, I can't seem to find the edit button.

Another thing that has been bothering me is transmission. I see gas scooters listed on eBay that feature automatic transmissions (this is the modified kick scooter type, not the ride on semi-motorcycles). However, I have been able to find no aftermarket transmission kits for my use. Despite my research on small engines, I've been unable to find anything regarding transmission within the engine. Any info?
Old 10-12-07, 11:17 PM
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Join Date: Jul 2001
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Welding a clutch onto the crankshaft wouldn't be advisable. Most all clutches have a setscrew to tighten down on the key (most all small engine cranks will be keyed unless you get into trimmer style engines). If not keyed, a machine shop can cut a keyway in it. You'll want to be able to replace the clutch, since they don't last forever.

I wouldn't be worried about using any kind of transmission on a scooter. Just a chain driven wheel should be fine. A 2hp briggs should have more than enough torque for a scooter provided the ratio isn't too high.

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