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FUN TIMES 12-01-00
FUN KART CLUTCHES
Do’s and Don’ts For Better installation and Maintenance
By Jim Donovan, Max-Torque Ltd.

1. When installing a clutch, slip a 3/16” x ½” key into the hub of the clutch. If the key does not drop into the key slot, DO NOT USE A HAMMER. File the key as necessary so it slips easily into the key slot. The clutch should slide onto the engine crankshaft without using force. Use emery paper or a very fine file to take off any burrs on the crankshaft. If need be, put a drop of oil or grease on the crankshaft to help the clutch slide on easily. (Note: Never use a hammer to install a clutch. This may result in damage to the clutch unit and affect performance of the unit.)

Always use a bolt, lock washer and a flat washer (1-1/8” diameter) to hold the clutch on the crankshaft. This is the safest method of securing the clutch. Set screws are used ONLY if the crankshaft is not drilled and tapped to accept the bolt and washer assembly. The clutch should be allowed to float slightly on the crankshaft to help self-align the clutch with the rear sprocket or pulley.

2. The gear ratio between the clutch sprocket and the driven sprocket should not be less than 1:6. What this means is that for every tooth on the clutch, there should be 6 on the rear or driven sprocket. Example: If the clutch has 10 teeth, you should have a minimum of 60 teeth on the rear sprocket. (Note: Standard fun kart sprocket are 60 and 72 teeth - #35 chain).

3. The maximum recommended tire diameter for a clutch application is 13”. Karts with larger tires should use a torque converter or jack-shaft to improving gearing.

4. Do not use a clutch key longer than 5/8” (.625).

5. Do not use the clutch to align with the rear sprocket. Rather, adjust the engine or move the rear sprocket. The sprocket or pulley must be on the exact same centerline, If not aligned properly, it will cause a side-load which will prematurely cause the clutch to fail and/or the belt or chain to constantly come off.

6. The crankshaft must be at least 2.3” in length. The clutch must be fully supported by the crankshaft. Standard 4-cycle crankshafts are ¾” in diameter. Some older engines also have 5/8” diameter crankshaft.

7. Never use the following lubricants on the clutch bushing or chain: Slick 50, Dynamite, or Energy Release. These type of lubricants are fine for internal combustion lubrication, but should never be used on the clutch or chain.

8. Using a tachometer, verify the true idle speed of the engine. The clutch will lock up fully once the speed of the engine exceeds 2,600 RPM. If the engine has a gear reduction unit on it, the clutch will not work properly because the output shaft speed has been reduced below the designed lock-up of the clutch.

9. Do not use a restrictor on the engine or gas pedal. Let the engine run at the full recommended speed of 3,600 RPM.

10. Always use a guard around the clutch and chain. Be sure to keep hands, hair and loose clothing away from the chain, sprockets and any other moving or rotating parts. Safety should be the #1 priority.

11. To maximize the life of the clutch, do not ride the throttle and brake at the same time. Avoid short stop and go driving.

12. The weight of the kart and driver should not be exceed 350 pounds.

About the author: Jim Donovan is the owner of Max-Torque Ltd., Melrose Park, Illinois. Telephone: 708-574-7022. E-mail: info@maxtorque.com. Web: www.maxtorque.com.

END

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Post Office Box 101
Wheaton, IL 60189 USA
Telephone: 630-653-7368
Fax: 630-653-2637
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