Yes, you can easily start a Stihl MS250 chainsaw if you follow the correct steps. This guide will walk you through the process of getting your Stihl MS250 up and running smoothly, whether it’s a cold start or you’re encountering issues. We’ll cover everything from fuel mixture to basic maintenance to ensure your chainsaw performs at its best.
Getting Your Stihl MS250 Ready to Go
Starting a Stihl MS250 is straightforward once you know the process. This powerful yet manageable saw is popular for a reason. Let’s get it ready for action.
Essential Pre-Start Checks
Before you even think about pulling the starter cord, a few checks are crucial for safety and performance.
Fuel and Oil Levels
Your Stihl MS250 needs the right mix to run.
- Fuel: Always use the correct Stihl two-stroke engine oil mixed with fresh, unleaded gasoline. The recommended Stihl MS250 fuel mixture is 50:1. This means 50 parts gasoline to 1 part oil. Using the wrong mixture can damage your engine.
- For a 1-gallon mixture (128 ounces), you’ll need about 2.5 ounces of Stihl two-stroke oil.
- Always mix in a clean container and shake well.
- Bar and Chain Oil: Ensure the bar oil reservoir is full. This oil lubricates the chain and bar, preventing excessive wear and heat. Use a dedicated bar and chain oil, not motor oil.
Chain Tension
A loose chain can cause dangerous kickback. A chain that’s too tight will wear out quickly and strain the engine.
- Checking Tension:
- With the engine off and cool, grip the chain with gloves.
- Pull it around the bar. It should move freely.
- The chain should be snug against the bar but should drop slightly when you let go.
- Adjusting Tension: Locate the adjustment screw (often near the clutch cover). Turn it clockwise to tighten and counter-clockwise to loosen. Always check tension again after adjustments.
Air Filter
A clean air filter is vital for proper engine operation. If it’s clogged, your saw might run poorly or not start at all.
- Inspection: Remove the top cover. Inspect the air filter for dirt and debris.
- Cleaning: You can often clean a washable filter with warm, soapy water and let it dry completely. For paper filters, a light tap or compressed air can work, but replacement is best if it’s very dirty.
Spark Arrestor Screen
This screen in the muffler prevents sparks from escaping, reducing fire risk.
- Inspection: After the saw has cooled, remove the muffler cover. Carefully remove the spark arrestor screen.
- Cleaning: Clean any carbon buildup with a wire brush. If it’s damaged or excessively clogged, replace it.
Understanding Your Stihl MS250 Controls
Familiarize yourself with the key controls before attempting to start.
Master Control Lever (Choke/Run Switch)
This lever controls the choke and the run/stop function.
- Cold Start Position (Choke Engaged): When you push the master control lever down, it engages the choke. This enriches the fuel-air mixture, making it easier to start a cold engine.
- Run Position: Once the engine has fired briefly or if it’s warm, you’ll move the lever up to the “run” position, disengaging the choke.
- Stop Position: Pushing the lever all the way down past “run” engages the stop function.
Purge Bulb (Primer Bulb)
This small, clear bulb is located on top of the carburetor.
- Purpose: It pumps fresh fuel into the carburetor, ensuring it’s ready to ignite.
- How to Use: Press the purge bulb several times (usually 4-6) until you see fuel visibly move into the carburetor.
Starter Grip
This is what you pull to start the engine.
The Step-by-Step Starting Procedure for Your Stihl MS250
Here’s the correct sequence for starting Stihl MS250.
For a Cold Engine (Cold Start Stihl MS250)
- Safety First: Place the chainsaw on a firm, level surface. Ensure the chain brake is engaged (push forward). Keep your feet firmly planted, with your right foot in the rear handle loop and your left hand on the front handle for stability.
- Engage the Choke: Push the master control lever all the way down. This engages the choke.
- Prime the Carburetor: Press the purge bulb (primer bulb) 4-6 times until you see fuel entering the carburetor.
- Attempt First Start: Firmly grip the front handle with your left hand. Pull the starter cord with your right hand in a smooth, steady motion until you feel resistance, then give it a sharp, quick pull.
- You should hear the engine “cough” or “sputter.” This indicates it’s trying to start.
- Disengage the Choke: Immediately after the engine coughs, pull the master control lever up to the “run” position. This disengages the choke.
- Attempt Second Start: Pull the starter cord again with a smooth, steady motion. The engine should now start and run.
- Warm-Up: Allow the engine to idle for a few seconds to warm up. The idle speed might be a bit higher with the choke disengaged.
For a Warm Engine
If the engine is warm or has been recently used:
- Safety First: Place the chainsaw on a firm, level surface with the chain brake engaged.
- Disengage the Choke: Ensure the master control lever is in the “run” position (up). The choke should be off.
- Attempt Start: Grip the front handle firmly. Pull the starter cord with a smooth, steady motion. The engine should start.
What to Do If Your Stihl Chainsaw Won’t Start
If your Stihl chainsaw won’t start, don’t force it. Let’s troubleshoot.
Common Reasons for Starting Issues
- Incorrect Fuel Mixture: This is a very common culprit for troubleshooting Stihl MS250. Using the wrong gas-to-oil ratio or old fuel can prevent starting.
- Flooded Engine: If you pulled the starter cord too many times with the choke engaged, you might have flooded the engine with too much fuel.
- Dirty Air Filter: As mentioned earlier, a blocked air filter restricts airflow.
- Fouled Spark Plug: A dirty or damaged spark plug won’t ignite the fuel.
- Ignition Problems: Issues with the spark plug wire or ignition coil can prevent spark.
- Blocked Fuel Filter: A clogged fuel filter restricts fuel flow from the tank.
- Carburetor Issues: The carburetor may need adjustment or cleaning.
Troubleshooting Steps
- Check the Fuel: Ensure you have the correct Stihl MS250 fuel mixture and that the fuel is fresh. If in doubt, drain the old fuel and refill with a fresh 50:1 mix.
- Dealing with a Flooded Engine:
- Turn the master control lever to the “stop” position.
- Engage the choke (push lever down).
- Pull the starter cord a few times to clear excess fuel from the cylinder.
- Move the master control lever to the “run” position (up).
- Attempt to start the chainsaw. It might still take a few pulls.
- Inspect the Spark Plug:
- Remove the spark plug cap.
- Use a spark plug wrench to remove the spark plug.
- Check for fouling (black, oily residue).
- Clean with a wire brush or replace if necessary. Ensure the gap is set correctly (check your owner’s manual).
- Reinstall the spark plug and spark plug cap.
- Verify Air and Fuel Filters:
- Clean or replace the air filter if it’s dirty.
- Check the fuel filter (usually inside the fuel tank, attached to the fuel line). If it looks clogged, it needs to be replaced.
- Carburetor Adjustment:
- While sometimes the issue, carburetor adjustment is best left to those familiar with small engines. If other steps fail, this might be the problem.
Starting Your Stihl MS250 for the First Time (Stihl MS250 First Start)
If your Stihl MS250 is brand new or has been in storage for a while, the Stihl MS250 first start process is the same as a cold start.
- Unboxing and Assembly: Ensure the bar and chain are correctly installed and tensioned.
- Fueling: Mix your fuel and oil and fill the tank.
- Follow Cold Start Procedure: Carefully follow the cold start steps outlined above. The engine might require a few more pulls to get the fuel through all the lines.
Fine-Tuning: Stihl MS250 Idle Adjustment
Once your saw is running, proper idling is important. Incorrect idling can lead to stalling or poor performance.
Why Adjust Idle?
The idle speed ensures the engine runs smoothly when not cutting and that the chain doesn’t spin at idle.
Finding the Idle Speed Screws
On the carburetor, you’ll typically find two or three adjustment screws:
- L (Low) Screw: Affects idle and low-speed performance.
- H (High) Screw: Affects high-speed performance.
- T (Idle Speed) Screw: This screw directly controls the engine’s idle speed. It often contacts a linkage on the throttle.
Steps for Stihl MS250 Idle Adjustment
- Warm Up the Engine: Start the chainsaw and let it run for a few minutes until it reaches operating temperature.
- Check Idle Speed: Listen to the engine. It should idle smoothly without stalling. The chain should not move.
- Adjust the Idle Speed Screw (T):
- If the engine is idling too low (stalling or rough), turn the “T” screw clockwise slightly.
- If the engine is idling too high (chain might be slowly creeping), turn the “T” screw counter-clockwise slightly.
- Fine-Tuning (Optional, Use Caution): If the saw still isn’t running perfectly at idle, very small adjustments to the “L” screw might be necessary, but this is more advanced. Turning the “L” screw too far can cause poor acceleration or stalling. Always make tiny adjustments and test. If you’re unsure, consult your owner’s manual or a professional.
Important Note: Modern Stihl chainsaws, including the MS250, often have factory-set carburetors that may not require adjustment under normal circumstances. Only adjust if you notice issues with idle speed.
Stihl MS250 Maintenance for Longevity
Regular Stihl MS250 maintenance will keep your saw running reliably and safely for years to come.
Routine Maintenance Schedule
| Task | Frequency | Notes |
|---|---|---|
| Clean Air Filter | After each use or daily | Essential for performance. |
| Check Chain Tension | Before each use | Crucial for safety and saw longevity. |
| Clean Bar and Sprocket | After each use | Remove sawdust and debris. |
| Check Bar Oil Level | Before each use | Ensure proper lubrication. |
| Clean Spark Arrestor | As needed, or every 25 hours of use | Prevents overheating and potential fires. |
| Clean Spark Plug | Every 50 hours of use, or annually | Replace if fouled or worn. |
| Clean Cooling Fins | As needed | Prevents engine overheating. |
| Check Fuel Filter | Every 50 hours of use, or if performance dips | Replace if clogged. |
| Inspect Chain and Bar | Regularly | Look for wear, damage, or dulling. Sharpen or replace as needed. |
| Stihl MS250 maintenance | Seasonal or as per owner’s manual | Consider professional service if experiencing persistent issues. |
Sharpening Your Chainsaw Chain
A sharp chain cuts efficiently and safely. A dull chain requires more force, puts strain on the engine, and increases the risk of kickback.
- Tools Needed: A round file of the correct diameter for your chain (check your manual), a file guide, a flat file, and a wrench.
- Sharpening Process:
- Ensure the chain is tensioned correctly.
- Locate the longest cutter on the chain.
- Place the round file in the file guide and align it with the top of the cutter at the recommended angle (usually 30-35 degrees).
- File from the inside out with firm, even strokes. Count your strokes.
- Repeat for all cutters on that side of the chain.
- Flip the saw over or adjust your position.
- Sharpen the cutters on the other side, using the same number of strokes and maintaining the correct angle.
- Use the flat file to file down the depth gauges if they are too high, but be conservative. This is done less frequently than sharpening cutters.
- Check chain tension again after sharpening.
Cleaning and Lubrication
- Bar Groove: Use a small brush or screwdriver to clean out the groove in the guide bar where the chain sits.
- Sprocket: Clean the drive sprocket area for sawdust and debris.
- Oiling: Ensure the oiler hole on the bar is clear, allowing oil to reach the sprocket.
Frequently Asked Questions About Starting Your Stihl MS250
Here are answers to common questions about the Stihl MS250 startup.
Q1: What is the correct Stihl MS250 fuel mixture?
A1: The recommended Stihl MS250 fuel mixture is 50:1 (50 parts gasoline to 1 part Stihl two-stroke engine oil).
Q2: My Stihl MS250 won’t start after I filled it with fresh fuel. What should I do?
A2: First, double-check the Stihl MS250 fuel mixture. If it’s correct, try the cold start Stihl MS250 procedure again, ensuring you’ve primed the carburetor with the purge bulb. If it still won’t start, check the spark plug and air filter, as these are common issues.
Q3: Can I start my Stihl MS250 without the choke engaged?
A3: You can try, but it’s much harder, especially if the engine is cold. The choke enriches the fuel mixture, making starting easier. It’s best to follow the starting Stihl MS250 procedure with the choke for a cold engine.
Q4: My Stihl MS250 is running rough and stalling. What could be wrong?
A4: This could be due to a dirty air filter, a fouled spark plug, an incorrect fuel mixture, or carburetor issues. Review the troubleshooting Stihl MS250 section for solutions. Improper Stihl MS250 idle adjustment can also cause rough running.
Q5: How do I prime my Stihl MS250?
A5: Locate the small, clear purge bulb (primer bulb) on the carburetor. Press it repeatedly (4-6 times) until you see fuel visible inside it and moving towards the carburetor. This is part of how to prime Stihl MS250.
Q6: The chain on my Stihl MS250 is moving when the saw is idling. How do I fix this?
A6: This indicates your idle speed is set too high. You need to perform an Stihl MS250 idle adjustment. Locate the idle speed screw (often labeled “T”) on the carburetor and turn it counter-clockwise slightly until the chain stops moving at idle.
Q7: Is it normal for the saw to run faster after I disengage the choke?
A7: Yes, it’s normal. Disengaging the choke leans out the fuel mixture, and the engine speed might increase slightly and then settle into a normal idle.
By following these steps and performing regular Stihl MS250 maintenance, you can ensure your chainsaw starts reliably and performs efficiently for all your cutting needs. Remember to always prioritize safety and consult your owner’s manual for specific details related to your model.