Stihl 028 Carburetor Replacement Guide (7 Pro Chainsaw Hacks)

The Stihl 028 is a legendary chainsaw, known for its reliability and power. However, like any engine, the carburetor can become clogged or damaged over time, leading to poor performance. Replacing it isn’t as daunting as it seems, and with the right knowledge and a few simple tools, you can tackle this job yourself. My own experience with a stubborn 028, refusing to start after a long winter, led me down this path. After cleaning the carb multiple times with no luck, I realized replacement was the only option.

Why Replace Your Stihl 028 Carburetor?

Before we get started, let’s understand why a carburetor replacement might be necessary. Common symptoms include:

Difficulty starting: The engine cranks but refuses to fire up.
Rough idling: The engine idles erratically or stalls frequently.
Poor acceleration: The engine hesitates or lacks power when you try to accelerate.
Excessive smoking: The engine burns fuel inefficiently, resulting in a smoky exhaust.
Flooding: The engine becomes flooded with fuel, preventing it from starting.

These issues often stem from a clogged carburetor, worn-out diaphragms, or damaged internal components. While cleaning can sometimes resolve these problems, a replacement is often the most reliable solution, especially for older carburetors. I’ve found that after years of use, the tiny passages in the carb become so gummed up that no amount of cleaner can restore them to their original function.

Tools and Materials You’ll Need

Before you begin, gather the following tools and materials:

New Carburetor: Make sure you get the correct replacement carburetor for your Stihl 028. Check the model and serial number of your chainsaw to ensure compatibility. I always recommend buying from a reputable supplier to avoid low-quality knockoffs.
Screwdrivers: A set of screwdrivers, including both flathead and Phillips head, in various sizes. A small, precision screwdriver set is particularly useful for adjusting the carburetor.
Pliers: Needle-nose pliers and standard pliers for removing and installing hoses and other components.
Wrenches: A set of wrenches to remove any bolts or nuts securing the carburetor.
Carburetor Cleaner: Use carburetor cleaner to clean any surrounding parts and the intake manifold.
Shop Rags: Plenty of shop rags to wipe up any spills and keep your workspace clean.
Fuel Line Clamps: To temporarily pinch off fuel lines.
Spark Plug Wrench: To remove the spark plug (optional, but recommended).
Small brush: A small brush like a toothbrush to clean the area around the carburetor.
Safety Glasses and Gloves: Always wear safety glasses and gloves to protect yourself from fuel and debris.
Camera or Smartphone: Taking photos as you disassemble the carburetor can be incredibly helpful for reassembly.
Service Manual (Optional): A service manual for your Stihl 028 can provide detailed diagrams and instructions.

Step-by-Step Carburetor Replacement Guide

Now, let’s get down to the nitty-gritty. Here’s a detailed, step-by-step guide to replacing the carburetor on your Stihl 028.

Step 1: Safety First!

Before you even think about touching your chainsaw, disconnect the spark plug wire. This prevents accidental starting during the replacement process. Trust me, I’ve seen enough near-misses in the woods to know this is non-negotiable. Also, ensure the chainsaw is cool to the touch.

Step 2: Remove the Air Filter Cover and Air Filter

Locate the air filter cover on your Stihl 028. It’s typically held in place by a screw or two. Remove the screws and carefully remove the cover. Then, remove the air filter itself. Take note of how the filter is positioned, as you’ll need to reinstall it the same way.

Step 3: Disconnect the Fuel Line and Impulse Line

Locate the fuel line and impulse line connected to the carburetor. The fuel line is usually a thicker rubber hose, while the impulse line is thinner. Use fuel line clamps to pinch off the fuel line to prevent fuel from spilling. Carefully disconnect both lines from the carburetor. A pair of needle-nose pliers can be helpful for this step.

Pro Hack #1: Label Your Lines! Before disconnecting the fuel and impulse lines, use a piece of tape and a pen to label each line. This will save you a lot of headache during reassembly. I learned this the hard way after spending an hour trying to figure out which line went where on a particularly stubborn 028.

Step 4: Remove the Throttle Linkage and Choke Linkage

The throttle linkage and choke linkage connect the carburetor to the throttle trigger and choke lever, respectively. Carefully disconnect these linkages from the carburetor. Take note of how they are connected, as you’ll need to reconnect them in the same way. Again, a picture can be a lifesaver here.

Step 5: Remove the Carburetor Mounting Bolts or Nuts

The carburetor is typically held in place by two or more bolts or nuts. Use a wrench or socket to remove these fasteners. Once the fasteners are removed, carefully pull the carburetor away from the engine.

Step 6: Inspect the Intake Manifold

With the carburetor removed, take a moment to inspect the intake manifold. Look for any cracks, damage, or debris. Clean the intake manifold with carburetor cleaner and a shop rag. If the intake manifold is damaged, it will need to be replaced.

Pro Hack #2: Intake Manifold Inspection. A cracked or leaking intake manifold can cause the same symptoms as a bad carburetor. Before installing the new carburetor, spray some carburetor cleaner around the intake manifold while the engine is running (if possible). If the engine speed changes, you likely have a leak.

Step 7: Install the New Carburetor

Now it’s time to install the new carburetor. Carefully align the carburetor with the intake manifold and install the mounting bolts or nuts. Tighten the fasteners securely, but don’t overtighten them.

Step 8: Reconnect the Throttle Linkage and Choke Linkage

Reconnect the throttle linkage and choke linkage to the new carburetor. Make sure the linkages are properly connected and move freely.

Step 9: Reconnect the Fuel Line and Impulse Line

Remove the fuel line clamps and reconnect the fuel line and impulse line to the new carburetor. Ensure the lines are securely attached and there are no leaks.

Step 10: Reinstall the Air Filter and Air Filter Cover

Reinstall the air filter and air filter cover. Make sure the air filter is properly positioned and the cover is securely fastened.

Step 11: Reconnect the Spark Plug Wire

Reconnect the spark plug wire to the spark plug.

Step 12: Adjust the Carburetor (if necessary)

Most new carburetors will require some adjustment to ensure optimal performance. Refer to your Stihl 028 service manual for specific instructions on adjusting the carburetor.

Pro Hack #3: Carburetor Adjustment Basics. The carburetor typically has three adjustment screws:

L (Low Speed): Controls the fuel mixture at idle.
H (High Speed): Controls the fuel mixture at high RPMs.
LA (Idle Speed): Adjusts the engine’s idle speed.

Start by turning both the L and H screws all the way in (clockwise) until they are lightly seated. Then, back them out (counterclockwise) 1 to 1.5 turns. Start the engine and adjust the L screw until the engine idles smoothly. Then, adjust the LA screw until the engine idles at the correct RPM (refer to your service manual). Finally, adjust the H screw for optimal high-speed performance.

Pro Hack #4: The Paper Test. An old mechanic trick is to hold a piece of paper near the exhaust while the engine is running at high speed. If the paper gets wet with fuel, the H screw is too rich (turn it in slightly). If the engine bogs down, the H screw is too lean (turn it out slightly).

Step 13: Test the Chainsaw

Start the chainsaw and let it warm up for a few minutes. Test the throttle response and ensure the engine is running smoothly at both idle and high speeds. If you experience any problems, recheck your connections and readjust the carburetor as needed.

Advanced Tips and Tricks

Replacing the carburetor is a great start, but here are a few extra tips to keep your Stihl 028 running like a champ.

Pro Hack #5: Fuel Filter Replacement

While you’re working on the fuel system, it’s a good idea to replace the fuel filter. The fuel filter is located inside the fuel tank and can become clogged over time, restricting fuel flow. I recommend replacing it annually, especially if you use your chainsaw frequently.

Pro Hack #6: Spark Plug Inspection and Replacement

A worn or fouled spark plug can also cause starting and performance problems. Inspect the spark plug and replace it if necessary. A healthy spark plug should have a clean, dry electrode and a gap that is within the manufacturer’s specifications.

Pro Hack #7: Regular Maintenance

The best way to keep your Stihl 028 running smoothly is to perform regular maintenance. This includes:

Cleaning the air filter regularly.
Sharpening the chain regularly.
Checking the bar and chain oil level.
Inspecting the fuel lines and connections.
Storing the chainsaw properly when not in use.

I always drain the fuel from my chainsaw before storing it for the winter. Ethanol-blended fuels can gum up the carburetor and fuel lines if left sitting for extended periods.

Common Mistakes to Avoid

Here are a few common mistakes to avoid when replacing your Stihl 028 carburetor:

Using the wrong carburetor: Make sure you get the correct replacement carburetor for your specific Stihl 028 model.
Forgetting to disconnect the spark plug wire: This is a safety hazard and can lead to accidental starting.
Overtightening the carburetor mounting bolts: This can damage the carburetor or intake manifold.
Not adjusting the carburetor properly: A poorly adjusted carburetor can cause performance problems and damage the engine.
Using old or contaminated fuel: Always use fresh, high-quality fuel in your chainsaw.

Troubleshooting Tips

If you’re still having problems after replacing the carburetor, here are a few troubleshooting tips:

Check for fuel leaks: Inspect the fuel lines and connections for any leaks.
Check the spark plug: Make sure the spark plug is clean and properly gapped.
Check the compression: Low compression can cause starting and performance problems.
Check the ignition system: A faulty ignition system can prevent the engine from starting.

If you’ve tried these troubleshooting tips and are still having problems, it’s best to take your chainsaw to a qualified repair shop.

Case Study: Reviving a Neglected Stihl 028

I once had a friend who inherited an old Stihl 028 from his grandfather. The chainsaw had been sitting in a shed for years and was in rough shape. He brought it to me, hoping I could get it running again.

After a thorough inspection, I determined that the carburetor was completely clogged and the fuel lines were cracked. I replaced the carburetor, fuel lines, and fuel filter. I also cleaned the air filter and replaced the spark plug.

After a few pulls, the old 028 roared back to life. My friend was amazed. He used the chainsaw to clear brush and cut firewood for his cabin. He was so grateful that he had his grandfather’s chainsaw back in working condition.

This experience reinforced the importance of regular maintenance and the value of a well-maintained chainsaw.

Stihl 028 Carburetor Replacement Guide (7 Pro Chainsaw Hacks)