How To Start A Stihl MS 250 Chainsaw: The Complete Step-by-Step Guide
Starting a Stihl MS 250 requires a precise sequence of actions involving the Master Control Lever, the decompression or choke valve, and proper pull-cord technique to prevent engine flooding. Mastering this cold and warm start protocol ensures reliable 45.4 cc engine ignition, preserves the pull-rope mechanism, and minimizes fuel fouling during routine property maintenance or firewood harvesting.
Pre-Operation and Safety Equipment Checklist
Operating a mid-range chainsaw like the Stihl MS 250 demands strict adherence to safety protocols and foundational equipment preparation. Before touching the starter rope, you must verify the mechanical integrity of the 16-inch or 18-inch guide bar, the tension of the Oilomatic chain, and the levels of both 2-stroke engine oil mixture (set at a strict 50:1 ratio) and bar and chain oil. Skipping these checks can result in premature bar wear, chain throw, or engine seizure.
- Essential Gear and Tools: ANSI-approved safety glasses, heavy-duty ballistic nylon chainsaw chaps, steel-toe logging boots, heavy work gloves, hearing protection rated at a minimum of 22 NRR, a combination wrench (scrench), and fresh 92+ octane fuel mixed with high-grade Stihl HP Ultra synthetic 2-stroke oil.
- Prerequisite Knowledge and Standards: Familiarity with kickback zones, chain brake engagement mechanics, and the specific operation of the Stihl Master Control Lever. Users must also understand how to identify a flooded engine versus a standard cold-start condition.
- Benchmarks and Timeframes: Pre-flight checks and starting sequence execution take approximately 3 to 5 minutes. The MS 250 features a power-to-weight ratio of 0.2 kW/kg, making it a responsive 2.3 kW powerhouse that demands steady footing and a firm two-handed grip during ignition.
Step-by-Step Procedure for Starting Your Stihl MS 250
Step 1: Engage the Chain Brake and Secure the Saw
Place the Stihl MS 250 on a flat, solid, and clear patch of ground free of loose debris or brush that could be sucked into the starter housing cooling slots. Push the front hand guard forward toward the guide bar tip to positively engage the chain brake.
Warning: Never attempt a drop-start—holding the saw by the top handle and pulling the starter cord with the other hand. This dangerous technique violates OSHA safety standards, removes critical control of the throttle, and dramatically increases the risk of loss of control or severe lacerations.
Step 2: Configure the Master Control Lever for a Cold Start
Locate the black Master Control Lever on the rear handle. If the engine is completely cold (has not run recently or ambient temperatures are low), press the throttle trigger and throttle trigger lockout simultaneously while pushing the Master Control Lever all the way down into the full choke position (symbolized by a closed choke valve). Release the throttle trigger first, then allow the lever to lock into the bottom choke notch.
Pro-Tip: If the saw has been running recently and the engine block is warm, skip the full choke position. Instead, push the Master Control Lever down and up one notch into the warm-start or run position to prevent immediate engine flooding.
Step 3: Set Your Stance and Pull the Starter Rope
Adopt a stable, ergonomic stance to brace the saw against unexpected kickback or movement. Place your right foot firmly into the rear handle opening to anchor the saw to the ground. Place your left hand firmly on the wrap-around front handlebar, maintaining a locked elbow. Pull the starter grip slowly with your right hand until you feel the piston hit compression resistance, then pull sharply, smoothly, and vertically upward with a swift motion.
Warning: Never pull the starter rope out to its full maximum extension of the starter housing, as this can snap the recoil spring or damage the starter cord. Do not let the starter grip snap back uncontrollably against the housing; always guide it back manually.
Step 4: Listen for the First Firing Pulse and Adjust Choke
Continue pulling the starter rope until the engine gives a brief, muffled pop or "first firing" sound, which indicates the air-fuel mixture has ignited within the cylinder. Immediately upon hearing or feeling this pop, move the Master Control Lever up one notch into the half-choke or warm-start position. Pull the starter rope again; the engine should fire and start running smoothly within one to two additional pulls.
Step 5: Disengage the Choke and Settle the Idle
Once the engine is running, briefly blip the throttle trigger with your right index finger. This automatic fast-idle release mechanism will cause the Master Control Lever to jump up one final notch into the standard Run (I) position, allowing the engine to drop down into a stable, idling speed while the chain remains stationary behind the engaged chain brake. Pull the front hand guard backward toward the rear handle to disengage the chain brake, and begin your cutting operation.
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Stihl MS 250 Technical Specifications and Operating Parameters
| Parameter | Technical Specification | Operational Impact |
|---|---|---|
| Displacement | 45.4 cc (2.77 cu. in.) | Generates high torque for cutting medium-diameter hardwoods and conifers. |
| Engine Power Output | 2.3 kW (3.1 bhp) | Provides optimal power-to-weight ratio for landowners and farmers. |
| Fuel-Oil Ratio | 50:1 (Stihl Synthetic 2-Stroke Oil) | Protects cylinder walls and bearings from scoring at high RPMs (up to 14,000 RPM). |
| Fuel Tank Capacity | 470 cc (15.9 fl. oz.) | Offers extended run time between refueling stops during heavy cutting tasks. |
| Chain Oil Tank Capacity | 200 cc (6.8 fl. oz.) | Ensures continuous lubrication of the guide bar and cutting teeth. |
Common Starting Failures and Field Fixes
- Root Cause (Engine Flooding): Pulling the starter cord too many times while the Master Control Lever is left in the full choke position, drawing excess fuel into the combustion chamber and soaking the spark plug.
- Actionable Fix: Move the Master Control Lever to the standard Run (I) position. Unscrew and remove the spark plug using your scrench, invert the saw, and pull the starter rope 5 to 6 times to expel excess fuel from the cylinder. Wipe the spark plug dry with a clean rag, check the electrode gap (set to 0.5 mm or 0.020 inches), reinstall the plug tightly, and restart using the warm-start procedure.
- Root Cause (Spark Plug Fouling or Carbon Buildup): Old fuel, incorrect oil mix ratio, or excessive idling resulting in carbon bridging across the spark plug electrodes.
- Actionable Fix: Remove the top engine cover, detach the spark plug boot, and extract the NGK BPMR7A or Bosch WSR 6 F spark plug. Clean carbon deposits with a wire brush or replace the plug entirely with a fresh unit before attempting ignition.
- Root Cause (Recoil Starter Engagement Failure): Worn starter pawls, a broken starter spring, or debris jammed inside the fan housing blocking the flywheel engagement dogs.
- Actionable Fix: Remove the four screws securing the starter housing assembly to the crankcase. Inspect the pawls and recoil spring for wear or obstruction, clear out wood chips and sawdust with compressed air, lubricate pivot points lightly with machine oil, and reassemble.
Frequently Asked Questions
Why does my Stihl MS 250 make a popping sound and then die?
That muffled pop indicates the engine has achieved its initial combustion stroke while on full choke. This is a normal and necessary indicator that the engine is ready; you must immediately move the Master Control Lever up one notch to the half-choke position before pulling again to keep it running.
How do I restart my Stihl MS 250 when the engine is already warm?
If the saw has been running recently, bypass the full choke entirely. Move the Master Control Lever directly from the Stop (O) position up to the warm-start/run position, brace the saw on the ground, and pull the starter cord with the throttle locked or slightly depressed.
What type of fuel should I use in a Stihl MS 250?
Always use fresh unleaded gasoline with an octane rating of 89 or higher, mixed thoroughly with high-grade Stihl HP Ultra synthetic 2-stroke oil at a strict 50:1 ratio. Alternatively, use Stihl MotoMix pre-mixed alkylate fuel, which contains no ethanol and prevents carburetor gumming during long periods of storage.
What should I do if the starter rope feels completely locked and won't pull?
A locked pull cord usually points to a hydro-locked engine caused by flooded fuel inside the cylinder, or a physical jam in the clutch drum and chain brake assembly. Remove the spark plug to release internal cylinder pressure and clear any pooled liquid, or inspect the clutch rim sprocket for tangled debris.
How often should I replace the spark plug and air filter on an MS 250?
Inspect the air filter and spark plug every 50 hours of operation or at least once per season. Clean foam filters with warm soapy water and replace paper filters or damaged spark plugs immediately to maintain proper fuel-air mixture ratios and easy starting performance.
Ready to tackle your wood-piling or tree-trimming projects with confidence? Ensure your Stihl MS 250 is serviced with fresh fuel and a sharp chain today for maximum cutting efficiency and reliable one-pull starts.
