[Loki]

Before disassembling the trimmer to service the clutch, consider whether the engine is simply idling too fast for the clutch shoes to retract. If so, adjusting the idle speed will also save gas and improve engine performance. To make the adjustment, locate the idle adjustment screw on the carburetor -- it's usually marked "I" -- and while the engine is running, turn the screw counterclockwise. The engine may slow down enough for the head to stop spinning, but if the engine dies before the head stops, it's time to service the clutch.

[1kewlchicu2]

The drive shaft in a string trimmer connects to the engine flywheel by means of a centrifugal clutch, usually located at the front of the engine housing. The clutch has two parts: a housing or drum connected to the trimmer shaft and a shoe assembly connected to the engine. Springs hold the shoes together and keep them compressed until the engine spins fast enough to force them apart, and they come in contact with the drum. When this contact is made, the drum also turns. It stops when the engine slows down and the springs draw the shoes back.

[Legion]

The clutch can fail in two different ways. In one scenario, the friction coating on the shoes wears out, they slip against the drum and the string head spins intermittently or not at all. This can also happen if oil gets into the clutch and contaminates the shoes. In the second scenario, the shoes never retract and always stay in contact with the drum. A broken spring is usually responsible for this type of malfunction, but it can also be the result of corrosion. If the spring is broken, you can sometimes replace it, but it's usually easier to replace the entire clutch. [links]

[jescro]

To get to the clutch, you need to remove the drive shaft, which is screwed to the engine housing. You may also have to remove the throttle cable and ignition wires. Be sure to empty the trimmer of any fuel before you begin. To remove the single screw holding the clutch drum, you must prevent the engine piston from moving; stuffing a nylon rope in the spark plug hole is a good way to do this. After unscrewing and removing the drum, you'll be able to unscrew the shoe assembly and repair or replace it as necessary. If you choose to replace it, it's a good idea to replace the drum at the same time. more

[migrainerelief4]

A string trimmer uses the same clutch mechanism as a chainsaw to prevent the working part of the tool from spinning when the engine is idling. If the clutch isn't working properly and the string won't stop turning, the tool can be dangerous -- it could damage something or even cause injury. The engine may be idling too fast -- which is easy to correct -- or the clutch may need servicing. here

[bosco]

Chris Deziel has a bachelor's degree in physics and a master's degree in humanities. Besides having an abiding interest in popular science, Deziel has been active in the building and home design trades since 1975. As a landscape builder, he helped establish two gardening companies.

[danny9robert]

Assuming that you're trying to stop the engine from rotating while removing the crankshaft pullet bolt, right?

[Etherael]

The easiest method is to use an impact wrench. At times, certain vehicles simply don't have the room to accommodate an impact wrench without removing the radiator or, even worse, vital air conditioning parts. Other methods are possible like wedging a screwdriver into the flywheel via the inspection plate cover which usually requires the help of a friend.

[Ervin02]

To tighten the bolt according to torque specs after job is finished, rotate crank to about 90 degrees BELOW top dead center, insert rope, turn crank clockwise until rope stops engine, then apply proper torque to bolt. [links]

[FreddyFender]

Well, a few years ago the electric PTO fell off. Somehow the bolt came loose. Anyway, I decided to fix it this weekend. I got a new bolt (original was lost). I remembered the trick of putting rope in the spark plug hole in order to stop the shaft from turning while tightening the bolt. Well, I kept turning the shaft and checking the depth of the piston with a screwdriver. I turned it in the direction of tightening the shaft bolt. It didn't seem to be moving much at all but I'm sure the shaft was turning. So I decided to go ahead and mount the clutch thinking that the shaft would eventually turn while I was tightening the clutch. Then I could find close to top and insert the rope. Well, I got to 45 ft lbs without any issue without using the rope.

[markvictor94]

I then proceeded to put the belt on. Everything back together and spark plug in. When I turn the key, there is only 1 click. The engine will not turn over. I removed the plug and I still only get 1 click. PTO is turned off. Battery is good as I started the mower last night and put it in the garage for today's work. However, I did put a portable battery on it just to be sure and still just 1 click.

[Inedible]

Mower ran fine prior to this. Been using it as a pull vehicle for garden trailer, etc. What did I do wrong? What could be the problem? [links]

[petree]

To perform the rope trick, unscrew the spark plug from the spark plug hole, and begin feeding a long piece of rope or something similar into the cylinder. The idea is to fill the cylinder with enough rope that the piston is not able to reach TDC (Top Dead Center), at which point it begins moving back down towards the crankcase. Once you have stopped the piston from moving, you can begin working on components attached to the crank. here

[jayrod]

When performing the rope trick, take care to avoid getting a piece of rope (particularly frayed ends) from getting caught under a ring or in a port. One of the best ways to prevent this from happening is to make sure that the top of the piston is above the exhaust port before feeding the rope into the spark plug hole. [links]

[asdf]

The rope trick is a technique you can employ to prevent your crank from turning. It is effectively an economical replacement for a piston stop.

[m0mchil]

Check out Moped TV (click the on demand button to browse old episodes) to see a video of using the rope trick to stop the movement of the piston. [links]

[ptime]

[links]