Go Kart Clutch Problems


Old 01-30-05, 07:55 AM
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Go Kart Clutch Problems

Hello All,

I have a project go kart that I need some help with.

I purchase a used Tecumseh go kart engine. Not for sure of the HP. Installed the engine and a new centrifugal clutch.

The problem is the kart will not move my 60 pound son. If I set the rear in the air and gas it the tires spin right up, but set the kart on the ground and put my son in it and it won’t budge. I even bought another centrifugal clutch, but that did not fix the problem. I believe the engine is turning enough rpm.

The engine continues to run with the cart on the ground and will move the cart about 3 inches with my son in it.

It acts like the clutch housing/sprocket part is worn and the clutches can not make enough contact/friction to get it moving. Hence the use of two new clutches.

This problem is aggravating because the whole mechanism is so darn simple and straight forward.
Any suggestions on the problem would be appreciated.

Thank you in advance.

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Old 01-31-05, 05:47 PM
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There are all types of centrifugal clutches and they engage at different rpm's. Make sure your clutch is made for a yard cart, a racing or high performance clutch might not engage in your engines' rpm range.

If your clutch has two or three metal "shoes" and several springs then it's engagement rpm depends on the weight of the shoes and the strength of the springs. Heavy shoes engage at a lower rpm, lighter shoes at higher rpm; light springs lower rpm, heavier springs higher rpm. By using various combinations of shoes and springs the engagement rpm can be adjusted pretty accurately.

Make sure you installed the key between the crank shaft and clutch when you installed it. Without the key, the clutch hub will just spin on the engine's shaft without transmitting much/any power.
Old 01-31-05, 05:50 PM
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I forgot to mention that some clutches are made or set to have the drive sprocket close to the engine (inboard) or the sprocket & chain out near the end of the engines shaft (outboard).
Old 01-31-05, 06:49 PM
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I have built my own homebuilt go-kart and used to have the same problem. I think your gearing may be to high. The clutch needs to have a small number of teeth (say 10) and the driven sprocket needs to have a larger amount of teeth (say 60). With 10 and 60 you'd achieve a 6:1 gear ratio which should be fine for your 60 pound son. I used to have my kart geared with a 12 clutch and a 36 driven gear and it burned up clutches right and left. It would rev up and then try to move the kart a couple feet, but the clutch would be slipping so much that it got hot and started to smoke, which made it slip even more. I would recommend that you have your son get on the kart and give it gas, when it revs up and the clutch is engaged, give the kart a push. My badly geared kart went nice and fast once I gave it a push start. If it works fine once it gets going, then the clutch may not be your problem. It's the gearing. Just swap out your driven gear for a bigger one or setup a jackshaft or torque converter. Maybe your clutch does have the wrong strength springs in it and I'm totally wrong, but I'd take a look at your gear ratio becuase that could likely be the problem.

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