Can you start a Stihl MS250 chainsaw easily? Yes, with the right knowledge and steps, starting your Stihl MS250 chainsaw can be a straightforward process. This guide will walk you through everything you need to know, from fuel and oil to the actual starting sequence and basic troubleshooting.
The Stihl MS250 is a popular choice for homeowners and professionals alike. It’s known for its power, reliability, and ease of use when it’s running correctly. However, like any piece of machinery, it needs proper care and attention to start up smoothly. This detailed guide will help you master the Stihl MS250 starting procedure, ensuring you can get to your cutting tasks efficiently and safely. We’ll cover essential aspects like preparing your chainsaw, understanding its controls, and what to do if it gives you trouble.
Preparing Your Stihl MS250 for Ignition
Before you even think about pulling the starter cord, proper preparation is key to a successful start. This involves ensuring your chainsaw is ready to go and has the correct fuel and oil.
The Right Fuel for Your Stihl MS250
Using the correct Stihl MS250 fuel mix is paramount for the engine’s longevity and performance. Stihl 2-stroke engines require a mix of gasoline and 2-stroke engine oil.
Fuel Mix Ratios
Stihl recommends a 50:1 fuel mix. This means:
- 50 parts gasoline to 1 part high-quality 2-stroke engine oil.
For example, if you use 1 gallon of gasoline, you’ll add 2.6 fluid ounces (or 80 ml) of 2-stroke oil.
Type of Gasoline
- Use unleaded gasoline with an octane rating of 89 or higher.
- Avoid using gasoline with ethanol content above 10% (E10), as it can damage the fuel system components over time.
- Always use fresh gasoline. Stored gasoline can degrade and cause starting problems.
Mixing Fuel
- Always mix fuel and oil in a clean, approved fuel container.
- First, add the oil to the container, then add the gasoline.
- Close the container tightly and shake it thoroughly to ensure the oil and gasoline are fully mixed.
- Only mix the amount of fuel you expect to use in the near future.
Stihl MS250 Oiling System: Bar and Chain Lubrication
A properly functioning Stihl MS250 oiling system is crucial for keeping your bar and chain lubricated, preventing wear and overheating. This system is automatic, but it needs to be checked and maintained.
Checking the Oil Reservoir
- Locate the oil reservoir cap. It’s usually marked with a bar and chain symbol.
- Ensure the reservoir is filled with Stihl’s specialized bar and chain oil or another high-quality bar and chain lubricant.
- Never use used oil, motor oil, or vegetable oil, as these will not provide adequate lubrication and can clog the oiler.
How the Oiling System Works
When the chainsaw is running, the oil pump dispenses oil from the reservoir through a small passage to the bar groove and the chain. This lubrication reduces friction between the chain and the bar, extending their life and ensuring efficient cutting.
Pre-Start Safety Checks
Safety first! Before you attempt to start your chainsaw, perform these checks:
- Chainsaw Condition: Inspect the chainsaw for any visible damage, loose parts, or leaks.
- Chain Tension: Ensure the chain is properly tensioned. It should be snug against the bar but still able to be pulled around by hand (wear gloves!). If it’s too loose, it can derail; too tight, and it will cause excessive wear.
- Chain Brake: Make sure the chain brake is engaged (pushed forward) when starting. This prevents the chain from spinning unexpectedly.
- Clearance: Ensure the area around you is clear of debris, bystanders, and anything you might snag the chainsaw on. Start on a flat, stable surface.
- Handlebars: Grip both handlebars firmly with both hands.
Deciphering the Stihl MS250 Controls for Starting
Your Stihl MS250 has several controls that are essential for starting. Familiarizing yourself with them is the next step.
The Stihl MS250 Choke Lever
The Stihl MS250 choke lever is vital for starting a cold engine. It enriches the fuel-air mixture by restricting airflow, making it easier for the engine to ignite.
- Cold Start Position (Choke Closed): This is typically a fully closed or partially closed position, often indicated by a symbol. It ensures a richer fuel-air mixture.
- Warm Start Position (Choke Open): Once the engine has fired and runs briefly, you’ll move the choke to the open position to allow more air and a leaner mixture for normal operation.
The Stihl MS250 Primer Bulb
The Stihl MS250 primer bulb is a small, clear rubber bulb located on top of the carburetor cover. Its purpose is to “prime” the carburetor with fuel before starting.
- How to Use: Press the primer bulb repeatedly (usually 5-10 times) until you see fuel visible inside the bulb. This pushes fuel from the fuel tank directly into the carburetor, making the initial start much easier, especially on a cold engine.
The Master Control Lever (or Combination Lever)
This lever, often located on the side of the handle, controls both the throttle and the choke.
- Start Position: When you move this lever down into the “start” position, it typically activates the choke and can also engage a fast idle setting.
- Run Position: Once the engine fires and runs, you’ll move this lever up to the “run” position, which opens the choke and disengages the fast idle.
The Step-by-Step Stihl MS250 Starting Procedure
Now that your chainsaw is prepared and you know the controls, let’s go through the recommended Stihl MS250 starting procedure.
Starting a Cold Engine
- Engage Chain Brake: Push the chain brake lever forward firmly until it clicks. This is crucial for safety.
- Prime the Carburetor: Locate the Stihl MS250 primer bulb. Press it firmly 5-10 times, or until you see fuel in the bulb.
- Set the Choke: Locate the Stihl MS250 choke lever (often part of the master control lever). Move it to the “cold start” or “choke closed” position. This might be indicated by a symbol or the lever being in the down position.
- Position the Chainsaw: Place the chainsaw on a firm, level surface. Ensure the guide bar and chain are not touching anything. Grip the front handlebar firmly with your left hand, keeping your thumb under the handle for extra security. Place your right foot through the rear handle loop to secure the saw against the ground.
- Pull the Starter Rope: Firmly and smoothly pull the starter rope out until you feel resistance, then give it a quick, strong pull. You are aiming for the engine to “chuff” or “pop” – meaning it tries to fire but doesn’t quite run.
- Disengage Choke: Once the engine “chuffs” (fires but doesn’t stay running), move the Stihl MS250 choke lever to the “warm start” or “choke open” position.
- Pull Starter Rope Again: Pull the starter rope again. The engine should now start and run.
- Disengage Chain Brake: As soon as the engine starts and runs, immediately push the chain brake lever forward (disengaging it) to allow the chain to spin.
- Allow to Warm Up: Let the engine run for about 10-20 seconds. You may need to gently squeeze the throttle trigger to keep it running if the Stihl MS250 idle speed is a bit low.
- Return Master Control Lever: Move the master control lever (which was in the start position) up to the run position. This fully opens the choke.
Starting a Warm Engine
If the chainsaw has been running recently, it’s considered “warm.”
- Engage Chain Brake: Push the chain brake lever forward.
- Primer Bulb (Optional): For a warm start, you may not need to use the primer bulb. If the saw is very warm or hasn’t been off for long, skip this step. If it seems a bit sluggish, a couple of presses might help.
- Set the Choke: Move the Stihl MS250 choke lever to the “warm start” or “choke open” position (up position). Do NOT use the cold start (closed choke) position for a warm engine, as it can flood the carburetor.
- Position the Chainsaw: Place the saw on a firm surface, secure it with your left hand and right foot.
- Pull Starter Rope: Pull the starter rope firmly and smoothly. The engine should start on the first or second pull.
- Disengage Chain Brake: Once the engine starts, disengage the chain brake immediately.
- Allow to Idle: Let the engine run at idle for a few seconds.
Maintaining Your Stihl MS250 for Easy Starts
Regular Stihl MS250 maintenance is critical for ensuring it starts easily every time. A well-maintained saw is a reliable saw.
Air Filter Cleaning
A clogged air filter restricts airflow to the carburetor, making the engine run rich and hard to start.
- Frequency: Check and clean the air filter after every few uses, or more often if you’re working in dusty conditions.
- Cleaning: Remove the filter cover, take out the filter, and tap it clean. For heavy dirt, wash it with warm, soapy water, rinse thoroughly, and let it air dry completely before reinstalling. Never use compressed air on a Stihl filter as it can damage the material.
Spark Plug Inspection and Replacement
The spark plug is responsible for igniting the fuel-air mixture. A fouled or worn spark plug can prevent starting.
- Inspection: Remove the spark plug using a spark plug wrench. Check for signs of wear, carbon buildup, or damage.
- Cleaning: If it’s dirty, clean it with a wire brush and check the gap using a feeler gauge. The correct gap for the MS250 is typically 0.020 inches (0.5 mm).
- Replacement: If the plug is heavily fouled, damaged, or you’re unsure, replace it with a new, recommended spark plug (e.g., NGK BPMR7A).
Fuel Filter Check
A dirty fuel filter can starve the engine of fuel.
- Location: The fuel filter is inside the fuel tank, attached to the fuel line.
- Checking: When you’re draining fuel or refilling, check the filter. If it looks dirty or clogged, it needs to be replaced.
Stihl MS250 Carburetor Adjustment
While the carburetor is factory set, over time or after extensive use, a Stihl MS250 carburetor adjustment might be necessary, especially if you’re experiencing rough idling or poor performance. However, it’s often best left to a qualified technician unless you have experience. Improper adjustment can damage the engine.
- Idle Speed Adjustment: The idle speed screw is usually a small screw on the carburetor. Turning it clockwise increases the idle speed, counter-clockwise decreases it. The goal is for the chain to not move when the saw is idling, but for the engine to run smoothly.
- High/Low Speed Needles: These adjustments are more complex and require specialized knowledge. If you suspect a carburetor issue beyond idle speed, consult your owner’s manual or a service center.
Troubleshooting Common Starting Issues
Even with perfect preparation, sometimes your Stihl MS250 might not start. Here’s some Stihl MS250 troubleshooting for common problems.
No Spark
If the engine doesn’t even try to fire:
- Check Spark Plug: Ensure it’s properly connected and not fouled.
- Check Ignition Module: If the plug is good, there might be an issue with the ignition module. This often requires professional diagnosis.
- Check Kill Switch: Make sure the kill switch is in the “run” position.
Flooded Engine
If you smell a lot of gasoline and the engine is making sputtering noises but not starting, it might be flooded.
- Disengage Choke: Make sure the choke is in the fully open position.
- Full Throttle: Hold the throttle wide open.
- Pull Rope: Pull the starter rope several times. This allows maximum air into the engine to help burn off excess fuel.
- Wait: Let the saw sit for 10-15 minutes to allow the excess fuel to evaporate.
- Restart: Try starting again with the choke in the open position and without using the primer bulb.
No Fuel Reaching the Carburetor
If you hear no sputtering or firing, and the primer bulb doesn’t seem to fill:
- Check Fuel Level: Ensure there is enough Stihl MS250 fuel mix in the tank.
- Check Fuel Cap Vent: The fuel cap has a vent that can get clogged, preventing fuel flow. Try slightly loosening the fuel cap.
- Check Fuel Lines: Inspect the fuel lines for kinks or damage.
- Check Fuel Filter: As mentioned in maintenance, a clogged fuel filter is a common culprit.
Engine Starts but Dies Immediately
This often indicates an issue with maintaining a proper fuel-air mixture once it’s running.
- Choke Position: Ensure you’ve moved the Stihl MS250 choke lever to the open position after the initial pop.
- Idle Speed: The Stihl MS250 idle speed might be set too low. Try gently increasing it by squeezing the throttle. If it consistently dies at idle, a minor Stihl MS250 carburetor adjustment might be needed.
- Air Filter: A dirty air filter can cause the engine to stall.
- Spark Arrestor Screen: The spark arrestor screen in the muffler can get clogged with carbon. This restricts exhaust flow and can cause the engine to run poorly or die. Clean it if necessary.
Advanced Stihl MS250 Maintenance
Beyond the basic checks, a few other Stihl MS250 maintenance tasks can ensure optimal performance and easy starting.
Spark Arrestor Screen Cleaning
The spark arrestor screen helps prevent sparks from exiting the muffler, reducing the risk of forest fires. Over time, carbon can build up on this screen, restricting exhaust flow and affecting engine performance, including starting.
- Location: The spark arrestor screen is located inside the muffler outlet.
- Cleaning: Remove the muffler cover (usually one screw). The screen is a mesh inside the muffler outlet. Carefully remove it (a small pick or screwdriver can help) and clean it with a wire brush. You can also soak it in a carburetor cleaner or a degreaser. Ensure it’s completely dry before reinstalling. Never operate a chainsaw without the spark arrestor screen.
General Cleaning
Keeping your chainsaw clean makes it easier to spot potential issues and ensures components function correctly.
- Body: Wipe down the saw with a damp cloth after use.
- Cooling Fins: Clean the cooling fins on the cylinder to prevent overheating.
- Bar Groove: Ensure the groove in the guide bar is free of sawdust and debris, as this is where the oil flows.
Stihl MS250 Assembly and Disassembly
While not directly related to starting, knowing basic Stihl MS250 assembly and disassembly can be helpful for maintenance tasks. For instance, removing the top cover to access the air filter or spark plug is a common procedure. Always refer to your owner’s manual for specific instructions on how to safely remove and reattach components.
Frequently Asked Questions (FAQ)
Q1: What is the correct Stihl MS250 fuel mix?
A1: The correct Stihl MS250 fuel mix is 50:1, meaning 50 parts gasoline to 1 part high-quality 2-stroke engine oil.
Q2: How often should I check the Stihl MS250 oiling system?
A2: You should check the Stihl MS250 oiling system reservoir every time you refuel the chainsaw. Ensure it’s filled with appropriate bar and chain oil.
Q3: My Stihl MS250 won’t start after sitting all winter. What should I do?
A3: Ensure you have fresh fuel mixed correctly. Check the air filter and spark plug. If it still won’t start, the carburetor might have stale fuel deposits and could need cleaning.
Q4: How do I adjust the Stihl MS250 idle speed?
A4: The Stihl MS250 idle speed is adjusted with a small screw on the carburetor. Turn it clockwise to increase idle speed and counter-clockwise to decrease it. Aim for a steady idle where the chain doesn’t move.
Q5: Can I use regular gasoline in my Stihl MS250?
A5: You should use unleaded gasoline with an octane rating of 89 or higher. Avoid gasoline with more than 10% ethanol (E10).
Q6: What does the Stihl MS250 primer bulb do?
A6: The Stihl MS250 primer bulb is used to pump fuel into the carburetor, making it easier to start a cold engine.
Q7: My Stihl MS250 starts but then dies. What’s wrong?
A7: This could be due to the choke being left on too long, the Stihl MS250 idle speed being too low, a dirty air filter, or a clogged spark arrestor screen.
By following these detailed steps and performing regular Stihl MS250 maintenance, you can ensure your chainsaw starts reliably and performs at its best. Happy cutting!