Can you start a Stihl MS250 chainsaw with a cold engine using a specific procedure? Yes, a Stihl MS250 chainsaw can be started with a cold engine by following a precise set of steps involving fuel, choke, and ignition.
The Stihl MS250 is a popular choice for homeowners and small landowners, known for its balance of power and user-friendliness. However, like any piece of machinery, knowing the proper starting procedure is key to its longevity and your safety. This guide will walk you through everything you need to know to get your Stihl MS250 up and running smoothly, from checking the fuel to troubleshooting common issues.
Preparing Your Stihl MS250 for Starting
Before you even think about pulling the starter cord, a few crucial preparation steps ensure safe and successful operation. Neglecting these can lead to frustration or, worse, damage to your chainsaw.
Ensuring the Correct Stihl 250 Fuel Mix
This is arguably the most critical step for any gasoline-powered engine, especially a two-stroke like the Stihl MS250. Using the wrong fuel mix can cause severe engine damage.
- The Golden Ratio: Stihl recommends a 50:1 fuel-to-oil ratio for their two-stroke engines. This means for every 50 parts of gasoline, you need 1 part of high-quality two-stroke engine oil.
- The Oil: Always use a dedicated two-stroke engine oil specifically designed for air-cooled engines. Stihl manufactures its own line of high-performance two-stroke oils, which are formulated to work perfectly with their engines. Avoid using outboard motor oil or other types of oil, as they are not designed for this application and can lead to engine problems.
- The Gasoline: Use fresh, unleaded gasoline with an octane rating of 89 or higher. Avoid using gasoline that has been stored for extended periods, as it can degrade and clog your carburetor. It’s best to buy gasoline in quantities you’ll use within a month or two.
- Mixing: Always mix the fuel and oil in a clean, approved fuel container. Never mix directly in the chainsaw’s fuel tank. Pour the gasoline in first, then add the correct amount of oil. Seal the container and shake it thoroughly to ensure the oil and gas are completely mixed.
Table 1: Fuel Mix Ratios
| Gasoline | Two-Stroke Oil | Total Volume |
|---|---|---|
| 1 Gallon (128 oz) | 2.56 oz | 1 Gallon + 2.56 oz |
| 5 Liters | 100 ml | 5 Liters + 100 ml |
| 2 Gallons (256 oz) | 5.12 oz | 2 Gallons + 5.12 oz |
Inspecting the Stihl 250 Spark Plug
The spark plug is the ignition source for your chainsaw. A fouled or damaged spark plug will prevent the engine from starting.
- Locating the Spark Plug: The spark plug is usually located under a protective cap on the side of the engine.
- Removing the Spark Plug: Use a spark plug wrench or a deep socket to carefully unscrew the spark plug.
- Checking for Damage: Inspect the spark plug for signs of wear, damage, or fouling. Fouling can appear as a black, sooty deposit on the electrode. If it’s heavily fouled or damaged, it needs to be replaced.
- Cleaning and Gap Adjustment: If the spark plug is only lightly fouled, you can try cleaning it with a wire brush and a bit of carburetor cleaner. Ensure the electrode gap is set correctly according to your Stihl MS250 owner’s manual. The typical gap for this model is around 0.020 inches (0.5 mm).
Checking the Air Filter
A clogged air filter restricts airflow to the engine, making it difficult to start and run efficiently.
- Accessing the Air Filter: The air filter is typically located under a cover on top of the carburetor.
- Inspection: Remove the cover and the air filter. Check if it’s dirty or clogged with sawdust and debris.
- Cleaning: You can often clean the air filter by tapping it gently to remove loose debris. For a more thorough cleaning, you can wash it with warm, soapy water, rinse it well, and let it dry completely before reinstalling it. Some air filters are designed to be replaced when dirty.
Verifying the Chain Brake
For safety, always ensure the chain brake is disengaged before attempting to start the chainsaw. The chain brake lever should be pushed forward, away from the handle.
The Stihl MS250 Starting Procedure: Step-by-Step
Now that your chainsaw is prepared, let’s dive into the specific steps for starting a Stihl MS250. This procedure is designed to prime the engine and provide the necessary spark and fuel for ignition.
Step 1: Engage the Stihl 250 Choke Setting
The choke is essential for starting a cold engine. It enriches the fuel-air mixture by restricting airflow, making it easier for the engine to ignite.
- Cold Engine: For a cold engine, move the choke lever to the “choke” or “start” position. This is usually indicated by a symbol or the word “CHOKE” on the lever.
- Warm Engine: If the engine is warm or has been recently run, the choke should not be fully engaged. You might only need to move it to the “half-choke” position or not use it at all.
Step 2: Activate the Stihl 250 Primer Bulb
The primer bulb is a small, clear plastic bulb located near the carburetor. Its purpose is to pump fuel into the carburetor, ensuring it has enough to start, especially when cold.
- Pressing the Primer Bulb: Press the primer bulb repeatedly until you see fuel flow through it. You should see small bubbles of fuel moving from the fuel tank towards the carburetor. Typically, 5-10 presses are sufficient. If you don’t see fuel moving, there might be a blockage in the fuel line or the primer bulb itself may be faulty.
Step 3: Engage the Throttle Lockout
The throttle lockout is a safety feature that prevents the engine from revving uncontrollably when you start it.
- Engage: Press the throttle trigger fully toward the rear handle. While holding the throttle trigger, press the throttle lockout lever (usually located just above the trigger) forward. This will hold the throttle in the open position.
Step 4: Pull the Starter Rope
This is where the engine begins to come to life.
- Positioning: Place the chainsaw on a firm, flat surface. Hold the front handle firmly with one hand.
- Pulling: Grasp the starter rope handle with your other hand and give it a short, sharp pull. You should hear the engine sputter or “kick.”
- Repeat: After the initial sputter, release the starter rope handle and pull it again. The engine should now attempt to run.
Step 5: Disengage the Choke (Transitioning to Run)
Once the engine sputters or tries to run, it means it’s getting enough fuel. Now you need to disengage the choke to allow for normal operation.
- Move the Choke: As soon as the engine sputters, move the choke lever back to the “run” or “off” position. If you don’t do this, the engine will likely flood and stall.
- Second Pull: Give the starter rope another pull. The engine should now start and run.
Step 6: Allow the Engine to Warm Up
After starting, let the engine run at idle for a short period to allow it to warm up. This helps prevent stalling when you engage the throttle.
Step 7: Disengage the Chain Brake
Once the engine is running smoothly, disengage the chain brake by pushing the lever forward, away from the front handle.
Step 8: Test the Throttle
Gently squeeze the throttle trigger to ensure the engine revs up and returns to idle smoothly.
Stihl 250 Troubleshooting: When Your Chainsaw Won’t Start
It’s frustrating when your Stihl MS250 won’t start. Several common issues can prevent it from firing up. Here’s a breakdown of what to check if your Stihl 250 won’t start.
No Spark or Weak Spark
A lack of spark is a primary reason for a no-start condition.
- Check the Stihl 250 Spark Plug: As mentioned earlier, inspect the spark plug. If it’s fouled, dirty, or damaged, replace it.
- Ignition Coil: If the spark plug is good, the issue could be with the ignition coil. This is a more complex repair that might require professional attention.
- Spark Plug Wire: Ensure the spark plug wire is securely connected to the spark plug.
Fuel Delivery Problems
If the engine is getting spark but not starting, it might not be getting enough fuel.
- Stihl 250 Fuel Mix: Double-check that you’re using the correct Stihl 250 fuel mix. Old or improperly mixed fuel can cause starting problems.
- Primer Bulb: If the primer bulb isn’t drawing fuel, it could be cracked or the fuel line might be blocked.
- Fuel Filter: A clogged fuel filter can restrict fuel flow. It’s usually located inside the fuel tank. You can often access it by pulling the fuel line out of the tank.
- Stihl 250 Carburetor Issues: The carburetor is the heart of fuel delivery. If it’s dirty or needs adjustment, it can cause starting problems.
Airflow Issues
Restricted airflow can also prevent starting.
- Air Filter: Ensure the air filter is clean and not blocked.
Stihl 250 Carburetor Adjustment
Sometimes, the carburetor needs a slight adjustment to ensure the correct fuel-air mixture for starting and idling. This is a delicate process and should be done carefully.
- Adjustment Screws: Most Stihl carburetors have adjustment screws for idle speed and mixture. However, on many modern Stihl saws like the MS250, these are often limited or sealed to prevent incorrect adjustments.
- Idle Speed Adjustment: If the engine starts but runs rough at idle or stalls, the idle speed screw might need adjustment. Turning it clockwise usually increases idle speed, and counter-clockwise decreases it.
- Mixture Adjustment (Limited): If your MS250 has accessible mixture screws (often labeled “L” for low-speed and “H” for high-speed), consult your owner’s manual for the correct procedure. Generally, “L” affects the idle and low-speed performance, while “H” affects higher RPMs.
- Professional Help: If you’re unsure about carburetor adjustment, it’s best to take it to a qualified service center. Incorrect adjustments can cause significant engine damage.
Flooded Engine
If you pull the starter rope too many times with the choke fully engaged, you can flood the engine with too much fuel.
- How to Fix a Flooded Engine: Move the choke lever to the “off” or “run” position. Hold the throttle trigger wide open. Pull the starter rope several times. This will help clear the excess fuel. Once the engine sputters, release the throttle and try starting it normally with the choke off.
Maintaining Your Stihl MS250 for Reliable Starting
Regular maintenance is key to ensuring your Stihl MS250 starts easily every time.
Fuel System Maintenance
- Fresh Fuel: Always use fresh fuel and the correct Stihl 250 fuel mix.
- Fuel Filter: Replace the fuel filter annually or as needed.
- Fuel Lines: Inspect fuel lines for cracks or leaks.
Ignition System Maintenance
- Stihl 250 Spark Plug: Inspect and clean or replace the spark plug regularly.
- Spark Arrestor Screen: Clean the spark arrestor screen in the muffler periodically to prevent it from becoming clogged with carbon, which can affect performance and starting.
Air System Maintenance
- Air Filter: Clean or replace the air filter regularly, especially if you work in dusty conditions.
General Cleaning
Keep your chainsaw clean. Sawdust and debris can accumulate and interfere with the operation of various components, including the starter mechanism and carburetor.
Frequently Asked Questions (FAQ)
What is the correct Stihl 250 fuel mix?
The correct Stihl 250 fuel mix is 50:1 (50 parts gasoline to 1 part high-quality two-stroke engine oil).
My Stihl 250 won’t start. What should I check first?
If your Stihl 250 won’t start, check the spark plug for proper function and cleanliness, ensure you have the correct Stihl 250 fuel mix, and verify the choke setting.
Can I adjust the Stihl 250 carburetor myself?
While some basic adjustments might be possible on certain models, it’s generally recommended to consult your owner’s manual or a professional for Stihl 250 carburetor adjustment, as incorrect settings can damage the engine.
How do I know if the Stihl 250 primer bulb is working?
You should see fuel moving through the primer bulb when you press it. If you don’t see any fuel movement, the bulb or fuel line may be faulty.
What are the signs of a bad Stihl 250 spark plug?
Signs of a bad Stihl 250 spark plug include heavy fouling (black, sooty deposits), damage to the electrode, or a lack of spark when tested.
What is the proper Stihl 250 choke setting for a cold start?
For a cold start, the Stihl 250 choke setting should be fully engaged (moved to the “choke” or “start” position).
How do I troubleshoot a Stihl 250 that keeps stalling?
If your Stihl 250 keeps stalling, check for clogged air filters, fuel delivery issues, or an incorrect idle speed adjustment.
What is the correct Stihl 250 starting procedure?
The correct Stihl 250 starting procedure involves preparing the fuel, setting the choke, priming the bulb, engaging the throttle lockout, pulling the starter rope until the engine sputters, disengaging the choke, pulling again to start, and then allowing the engine to warm up.
By following these detailed steps and maintenance tips, you’ll be well-equipped to start your Stihl MS250 chainsaw properly and keep it running reliably for years to come. Happy cutting!