To start a Stihl MS250 quickly, engage the chain brake, depress the throttle trigger lockout and trigger simultaneously, and move the Master Control Lever down to the Full Choke (bottom) position. Pull the starter rope until the engine "coughs" or briefly fires, then move the lever up one notch to the Half Choke (Warm Start) position. Pull the rope again until the engine runs, then immediately "blip" the throttle to return the lever to the Run (I) position.
The Stihl MS250 is a legendary mid-range chainsaw favored by homeowners and landowners for its impressive power-to-weight ratio. However, because it relies on a traditional carbureted engine rather than the newer electronic M-Tronic™ systems found on professional models, starting it requires a specific sequence and an understanding of the mechanical state of the engine. Mastering this process is the difference between a tool that starts in three pulls and a morning spent frustrated with a flooded engine.
Prerequisites and Safety Preparations
Before attempting to start the MS250, you must ensure both the machine and the operator are properly prepared. Chainsaws are high-torque cutting tools; a "quick" start should never bypass safety protocols.
Personal Protective Equipment (PPE)
In 2026, safety standards from organizations like OSHA remain stringent regarding chainsaw operation. You should always wear:
- Chainsaw Chaps: Rated for the chain speed of the MS250 (approx. 20 m/s).
- Head Protection: A hard hat with integrated ear muffs and a face shield.
- Footwear: Steel-toed boots with high-traction soles.
- Gloves: Heavy-duty leather or specialized chainsaw gloves to dampen vibration and protect against debris.
Inspecting the Machine
Ensure the guide bar is properly tensioned and the chain is sharp. A loose chain can fly off during the high-RPM burst that occurs immediately after a cold start. Check the fuel and oil levels. The MS250 requires a 50:1 gasoline-to-oil ratio. Using a high-quality synthetic oil like Stihl HP Ultra helps prevent carbon buildup in the exhaust port, which is a common cause of hard starting.
Understanding the Stihl Master Control Lever
The most important component for starting the MS250 is the Master Control Lever. This single switch manages the ignition circuit, the throttle shutter, and the choke flap. On the MS250, the lever has four positions:
- STOP (0): The ignition is off. The circuit is grounded, and the engine cannot fire.
- RUN (I): The normal operating position. The choke is open, and the ignition is live.
- WARM START (n): Also known as the "half-throttle" or "half-choke" position. The choke is open, but the throttle is slightly advanced to allow more air/fuel mix into the combustion chamber.
- COLD START (Full Choke): The choke flap is closed, and the throttle is partially open. This creates a rich fuel environment necessary for a cold engine.
Critical Note: To move the lever from RUN (I) down to the COLD START position, you must first depress the throttle trigger lockout (on top of the handle) and the throttle trigger itself. The lever is mechanically locked to prevent accidental choking during operation.
Step-by-Step Cold Start Procedure
A "cold start" refers to an engine that has not been run recently and is at ambient temperature. This is where most users struggle.
1. Set the Chain Brake
Push the front hand guard forward until it clicks. This engages the chain brake, preventing the chain from spinning when the engine fires. Because the MS250 starts at a high idle, starting without the brake engaged is a significant safety hazard.
2. Set the Controls
Depress the trigger lockout and the throttle trigger. While holding them, push the Master Control Lever all the way down to the Full Choke position. Release the trigger first, then the lever; the lever should stay in the bottom position.
3. Positioning the Saw
Place the chainsaw on level ground. Ensure the bar and chain are not touching any obstructions like rocks or branches. Put your right foot into the rear handle to pin the saw to the ground, and place your left hand firmly on the front handlebar, locking your elbow.
4. The "Cough" (Initial Ignition)
Pull the starter rope slowly until you feel resistance (the compression stroke), then pull it firmly and quickly. Repeat this until the engine makes a brief "cough" or "burp" sound. This indicates that the fuel has ignited, but the mixture is too rich for the engine to continue running on full choke.
Warning: Do not pull the rope more than 4–5 times on Full Choke. If you continue pulling after the engine has "coughed," you will flood the engine with raw gasoline.
5. Move to Half-Choke
Immediately move the Master Control Lever up one notch to the Warm Start (n) position. Do not touch the throttle trigger during this adjustment, as doing so will cause the lever to jump back to the Run position prematurely.
6. Starting the Engine
Pull the starter rope again. The engine should start within 1–3 pulls. Once it fires, it will run at a high RPM.
7. Blip the Throttle
Immediately "blip" (squeeze and release) the throttle trigger. This action automatically moves the Master Control Lever to the RUN (I) position and returns the engine to a normal idle speed. Pull the chain brake back toward the handle to begin cutting.
The Warm Start Procedure
If you have been working and turned the saw off for a few minutes to refuel or move a log, you do not need the full choke.
- Engage the Chain Brake.
- Move to Half-Choke (n): Depress the trigger and move the lever to the Warm Start position. You do not need to go down to Full Choke first.
- Pull to Start: Usually, one firm pull will suffice.
- Blip the Throttle: Return to the Run (I) position.
If the saw was only off for a few seconds, you can often leave the lever in the RUN (I) position and simply pull the rope. However, the Warm Start position is more reliable for "quick" restarts.
Quick Reference: Starting States and Lever Positions
| Engine State | Choke Position | Trigger Action | Key Sound/Goal |
|---|---|---|---|
| Cold (First Start) | Full Choke (Bottom) | Depressed to Set | A brief "cough" or "pop" |
| After "Cough" | Half Choke (Middle) | Do Not Touch | Engine starts and stays running |
| Warm (Restart) | Half Choke (Middle) | Depressed to Set | Engine starts immediately |
| Running/Idle | Run (I) | Squeeze to reset | Smooth idle, ready to cut |
| Flooded | Run (I) or Half | See Troubleshooting | Clear excess fuel from cylinder |
Troubleshooting a Stubborn MS250
If your MS250 does not start within the first 10 pulls, something is wrong. The most common issues involve fuel quality, ignition, or "operator-induced flooding."
How to Fix a Flooded Engine
If you missed the "cough" and kept pulling on Full Choke, the spark plug is likely soaked in fuel. To fix this:
- Move the Master Control Lever to the RUN (I) position (or the "Stop" position if you need to remove the plug).
- Remove the top shroud and unscrew the spark plug.
- If the plug is wet, dry it with a clean rag or use a lighter to burn off the excess fuel.
- With the plug removed, pull the starter rope 15–20 times to clear the combustion chamber of excess fuel.
- Reinstall the plug and attempt to start the saw in the RUN (I) position with the throttle held wide open.
Fuel Issues in 2026
Modern gasoline, especially blends with 10% or 15% ethanol (E10/E15), degrades quickly. Ethanol attracts moisture and can create a "gum" in the small orifices of the MS250's carburetor. If the saw has been sitting for more than 30 days with untreated fuel, the "quick start" becomes impossible because the fuel cannot atomize correctly. Always use a fuel stabilizer or, ideally, pre-mixed canned fuel like Stihl MotoMix for long-term reliability.
Maintenance for Fast Starting
A chainsaw is a system. If one part is neglected, the starting performance suffers:
- Air Filter: A clogged filter restricts air, making the mixture too rich. Clean the MS250’s fleece or felt filter every 5–10 hours of use.
- Spark Plug: Check the gap (0.5 mm or 0.02 inches). A fouled plug won't provide the hot spark needed for cold starts.
- Fuel Filter: Located inside the gas tank. If it’s clogged, the engine won't get enough fuel to sustain the initial ignition.
Mechanical Physics of the MS250 Start
Understanding the physics can help you "feel" the saw. When you pull the rope, you are spinning the flywheel, which has magnets that pass by an ignition coil. This generates the electricity for the spark. Simultaneously, the piston's movement creates a vacuum that pulls fuel from the carburetor into the crankcase.
If you pull too slowly, you don't generate enough voltage or vacuum. If you pull too fast and "snap" the rope at the very end of its length, you risk breaking the starter pawls or the rope itself. The "quick start" technique is a smooth, accelerating pull—start slow to engage the pawls, then accelerate through the full length of the stroke.
Frequently Asked Questions
Why does my MS250 start and then immediately die?
This usually happens because the user didn't move the lever from Full Choke to Half Choke after the initial "cough." On Full Choke, the engine is starved for air once it actually begins to fire. Another cause is a "lean" carburetor setting; if the saw dies as soon as you give it gas, the "L" (Low-speed) jet may need a slight adjustment to allow more fuel at idle.
Is there a "Primer Bulb" on the Stihl MS250?
Standard MS250 models do not have a primer bulb. Some regional variants or "Easy2Start" (C-BE) versions might include one. If your saw does not have a bulb, the "Full Choke" pulls are what physically prime the engine by drawing fuel into the carb.
Can I start the MS250 without putting it on the ground?
While experienced professionals sometimes use a "drop start" technique (holding the front handle and "dropping" the saw while pulling the rope), this is strictly discouraged by Stihl's official safety manuals. Drop starting provides less control and increases the risk of the bar swinging into the operator's leg.
How often should I replace the spark plug to ensure quick starts?
For a homeowner using the saw for seasonal firewood, replacing the spark plug once a year is a good rule of thumb. If you notice heavy carbon deposits or a "bridged" electrode, replace it immediately. A clean spark is the most critical component for an "instant" start.
What is the "Easy2Start" system on some MS250 models?
The MS250 C-BE features the "Easy2Start" system, which uses a dual-spring starter mechanism. Instead of needing a fast, jerky pull, you pull the rope steadily and slowly. The rope tensions a spring, which then releases its energy all at once to spin the engine. The starting sequence (Choke positions) remains the same.
Next Actions for Reliable Performance
To ensure your Stihl MS250 continues to start quickly throughout 2026 and beyond, perform a "dry run" of the starting sequence before you head into the woods. If the saw has been in storage, replace the fuel with a fresh 50:1 mix. After finishing your work, never store the saw with fuel in the tank for more than a month; instead, run it dry or use a high-quality stabilizer. Regularly checking the spark arrestor screen in the muffler for soot buildup will also prevent the backpressure issues that often mimic a "hard start" scenario.
