How to Adjust a Centrifugal Clutch

by Cassandra Tribe

In some ways, a centrifugal clutch is the one device that makes small, gas-powered tools and conveyances possible. Effectively the centrifugal clutch does the same job as a torque converter, allowing an engine to idle at low rpm and engage at higher rpm where it makes adequate power. Without one, you'd have to manually disengage the clutch on your lawn mower, chainsaw or moped every time you slowed down, much as you do in a manual-transmission car. But centrifugal clutches are touchy things by nature; the smallest maladjustment can drastically change their performance and engagement rpm. Periodic adjustment to account for wear on the springs and clutch material is fairly simple in most cases.

Step 1

Locate the clutch on your engine; consult your owner's manual if necessary. If there is a cover over the clutch, remove the fasteners that hold it to the clutch and pull it off.

Step 2

Select a box wrench that fits the large lock-nut protruding from the center of the clutch case. Loosen the nut by turning it counterclockwise, but do not remove it.

Step 3

Using the flathead screwdriver, turn the adjuster screw located in the center of the locknut clockwise one turn.

Step 4

Slowly turn the adjuster screw counterclockwise until you feel slight resistance. Stop turning the screw. Turn the screw very slightly clockwise to back it off, no more than an one-eighth to one-quarter of a turn.

Step 5

Hold the screw steady with the screwdriver and tighten the lock-nut. You only need the nut snug, or "hand tight." Make sure the adjusting screw doesn't move as you're tighten the nut.

Step 6

Test-drive or test-run the tool or vehicle to ensure the clutch engages at the appropriate rpm, and that clutch engagement is neither too slow nor too sudden. If the clutch engages too quickly, back the adjustment screw off a half-turn. If engagement is too high or slow, tighten the adjusting screw up a bit.