How to test and replace the drive sprockets on a chainsaw

Ever wondered about the unsung hero in your chainsaw? Yep, the drive sprocket. It’s that behind-the-scenes part making sure your chain runs like a champ. But when it starts wearing down, you might notice your chain skipping or slipping ,  definitely not something you want when you’re cutting. Let’s check out how to test and swap out your chainsaw’s drive sprocket so you’re ready for your next project.

The information in this article may not apply exactly to your specific appliance model. For the most accurate guidance, it’s best to check your manufacturer’s documentation or reach out to us if you have any questions.

Get to know the chainsaw drive sprocket

The drive sprocket might be one of the smallest parts on your chainsaw, but it plays a big role in how your saw performs. Located near the clutch, the drive sprocket is what turns the chain around the bar when you hit the throttle. In short, it transfers power from the engine to the cutting chain, so if it’s worn out or damaged, your chainsaw won’t cut like it should (or at all).

There are two main types of drive sprockets:

• Rim sprockets, which are replaceable and separate from the clutch drum. These are common on many modern chainsaws and are easier (and cheaper) to replace.
• Spur sprockets, which are integrated into the clutch drum and usually found on smaller or older saws.

Over time, the sprocket teeth can wear down, become grooved, or even chip. This puts extra strain on the chain and bar and can cause uneven cutting or chain slippage. A good rule of thumb: if you’re replacing the chain, check the sprocket too. Replacing a worn sprocket along with the chain helps everything run smoother and last longer.

To inspect it, you’ll need to remove the side cover and bar, then check the sprocket for:

• Deep grooves or sharp ridges
• Uneven or pointed teeth
• Signs of rust or physical damage

Keeping your drive sprocket in good shape ensures better power transfer, longer chain life, and safer operation. It’s a small part that makes a big difference!

Safety precautions   

First things first: grab your tools and gear up for safety. If your chainsaw’s got an automatic chain brake, make sure it’s engaged. Here’s what you’ll need:

• If working indoors, make sure there is adequate ventilation to prevent the buildup of exhaust fumes. Carbon monoxide poisoning can be a serious risk.
• Wear insulated work gloves to protect your hands from sharp metal parts, pinching hazards and debris.
• Never attempt to service or repair while it is running or when the engine is still warm. Wait for all moving parts to come to a complete stop.
• Exercise extreme caution when working near blades, augers, or any other moving parts. Keep your hands, fingers, and clothing clear of these areas at all times.
• If the appliance has recently been used, give it plenty of time for any hot parts to cool down before working on it. 
• Empty the gas tank before beginning any work. Refill using fresh fuel. 
• Clean up oil spills right away to prevent slipping or other damage. 
• When working with wires, avoid touching any exposed wires or terminals. If you need to touch a wire, use a non-conductive tool or wear insulating gloves to prevent electrical shock.
• Take your time and don’t rush while working to prevent accidents and personal injuries.
• Work in a well-lit area so you can clearly see and access the interior parts.
• Clear your workspace of clutter and other obstacles. Keep children and pets away from the work area.
• Be gentle when handling or removing parts. Excessive force might damage the appliance or cause injury.
• Wear safety glasses when working with chemicals, dust or cleaning large debris to prevent injury. 
• When not in use, store the machine in a safe and dry location.

Gather tools 

• Screwdriver or wrench to remove the chainsaw cover
• Protective gloves and safety glasses
• Replacement sprocket  
• Cleaning rag and mild degreaser
• Flat surface or a good workspace

Replacing the chainsaw drive sprocket

Changing the sprocket keeps your chainsaw running smoothly and can extend the life of your bar and chain. Once you’ve figured out the sprocket needs replacing, here’s how to do it. Keep in mind, some chainsaws have special clip systems, while others just use screws or bolts. Always check your manufacturer documentation for specifics if you’re unsure.

Step 1: Remove the old sprocket

1. Make sure the chainsaw’s off and the spark plug wire’s disconnected. You don’t want any accidental starts.
2. Take off the chainsaw bar and chain, and set them aside somewhere safe.
3. Remove the clutch drum assembly according to your owner’s manual. On many models, you take off a retaining clip and slide the drum off the crankshaft.
4. If you’ve got a spur sprocket, it’s usually attached to the clutch drum and comes off with it. If it’s a rim sprocket setup, the rim piece lifts off the drum once you remove it.
5. Clean the area with a rag and a mild degreaser if needed, getting rid of any sawdust or gunk around the assembly.

Step 2: Install the new sprocket

1. Slide the new sprocket (or sprocket rim) onto the clutch drum. Make sure it aligns properly and fits snugly.
2. Put the clutch drum back onto the crankshaft. Usually, you replace the retaining clip or fastener to hold it securely.
3. Check that the sprocket spins smoothly on the clutch drum without too much friction. If it’s rubbing or misaligned, it can mess up how the chain runs.

Step 3: Reattach the chain and bar

1. Carefully loop your chain around the new sprocket, making sure the drive links sit properly in the teeth. Wrap the chain around the guide bar too.
2. Align the chainsaw bar on its mounting studs and put the cover back on. If your model has tensioning pins, make sure they line up with the bar’s adjustment holes.
3. Loosely tighten the bar cover screws at first. Then, use the tensioning screw (most chainsaws have one) to adjust the chain tension as recommended by the manufacturer.
4. Once you’re happy with the tension, tighten the bar cover screws completely.

Keep your chainsaw running smoothly

If you need any replacement parts for your appliances, you can enter your model number at AppliancePartsPros.com to locate and order them. Most orders arrive in just two business days, and we have tons of great information in our repair help section and YouTube videos to help you troubleshoot.

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