STIHL MS361 Parts Manual

The STIHL MS361 is a professional-grade chainsaw featuring a 59.0 cc engine, electronic ignition, anti-vibration system, STIHL Quickstop® inertia chain brake, side-access chain tensioner, tool-free fuel and oil caps, and a decompression valve. This parts manual provides detailed diagrams, part numbers, and ordering information for maintenance and repair. Below are key sections for safety, specifications, engine components, cutting attachments, fuel system, ignition system, and troubleshooting.

1. Features at a Glance 2. Safety Information 3. Specifications 4. Engine Assembly Parts 5. Cutting Attachment Parts 6. Fuel System Parts 7. Ignition System Parts 8. Air Filter System 9. Anti-Vibration System 10. Maintenance Schedule 11. Troubleshooting & Part Replacement

Features at a Glance

Key components: Engine cylinder, piston, carburetor, ignition module, fuel tank, oil tank, chain brake, guide bar, and cutting chain.

Feature	Description
Engine Displacement	59.0 cc (3.6 cu. in.)
Power Output	3.6 kW (4.9 hp)
Ignition System	Electronic, capacitor discharge
Anti-Vibration	STIHL anti-vibration system with spring elements
Chain Brake	STIHL Quickstop® inertia-activated
Fuel Tank Capacity	0.73 L (24.7 fl. oz.)
Oil Tank Capacity	0.36 L (12.2 fl. oz.)
Guide Bar Lengths	16" to 25" (40 cm to 63 cm)
Weight (powerhead)	6.2 kg (13.7 lbs)
Decompression Valve	Standard for easier starting

Safety Information

Always wear protective equipment: helmet, goggles, hearing protection, gloves, chainsaw chaps, and boots.

Read owner's manual before operation.
Inspect chainsaw before each use: chain tension, sharpness, lubrication.
Ensure chain brake functions properly.
Use correct fuel mix: 50:1 (STIHL HP Ultra oil with 89+ octane gasoline).
Operate with both hands on handles.

WARNING! Risk of kickback. Maintain secure footing; do not operate above shoulder height. Keep bystanders away.

Specifications

Engine Type: Single-cylinder, two-stroke, air-cooled.
Bore x Stroke: 47.0 mm x 34.0 mm.
Idle Speed: 2,800 RPM.
Maximum Power Speed: 9,500 RPM.
Fuel/Oil Ratio: 50:1 (STIHL HP Ultra).
Spark Plug: NGK BPMR7A (gap 0.5 mm / 0.020 in).
Chain Pitch: 3/8" or .325".
Chain Gauge: 0.050" or 0.063".
Sound Pressure Level: 106 dB(A).
Vibration Levels: Front handle 4.2 m/s²; rear handle 2.8 m/s².

Engine Assembly Parts

Cylinder, piston, crankshaft, connecting rod, bearings, seals, gaskets.

Cylinder: Part # 1128 020 1205 (with decompression valve). Piston: Part # 1128 030 2001. Crankshaft: Part # 1128 040 0801. Crankcase: Part # 1128 020 0601 (upper), 1128 020 0701 (lower). Gasket Set: Part # 1128 007 1050.

Refer to exploded diagram 1.1 for assembly order and torque specifications.

Cutting Attachment Parts

Guide bar, chain, sprocket, clutch, chain tensioner, bar nuts.

Guide Bar: STIHL Rollomatic® ES (Part # 3003 000 3920 for 20").
Cutting Chain: STIHL Oilomatic® (Part # 3633 005 0065 for 3/8" pitch, 0.050" gauge, 72 drive links).
Sprocket: Rim sprocket (Part # 1128 007 1003).
Clutch Assembly: Part # 1128 160 2001.
Chain Tensioner: Part # 1128 647 0600.

Tip: Match chain pitch and gauge to bar. Lubricate sprocket nose regularly.

Fuel System Parts

Fuel tank, cap, filter, lines, carburetor, primer bulb.

Carburetor: Zama C1Q-S267 (Part # 1128 120 0630).
Fuel Filter: Part # 0000 350 3504.
Fuel Line: Part # 1128 358 0500.
Fuel Tank: Part # 1128 350 0601.
Primer Bulb: Part # 1128 358 0600.
Impulse Line: Part # 1128 358 0700.

WARNING! Use only STIHL-approved fuel lines. Inspect for cracks annually.

Ignition System Parts

Ignition module, spark plug, stop switch, wiring harness.

Ignition Module: Part # 1128 400 1405. Spark Plug Boot: Part # 1128 122 0600. Stop Switch: Part # 1128 195 0600. Wiring Harness: Part # 1128 122 0700.

Air gap between ignition module and flywheel: 0.3 mm (0.012 in).

Air Filter System

Air filter, cover, pre-filter, securing knob.

Air Filter: Part # 1128 140 0603 (felt). Pre-Filter: Part # 1128 140 0610. Filter Cover: Part # 1128 140 0620. Knob: Part # 1128 647 0700.

Clean filter every 10 operating hours; replace if damaged.

Anti-Vibration System

Spring elements, rubber buffers, handle mounts.

Front AV Spring: Part # 1128 790 0600. Rear AV Spring: Part # 1128 790 0700. Rubber Buffer Set: Part # 1128 790 0800.

Inspect for wear every 100 hours; replace if springs are cracked or buffers deteriorated.

Maintenance Schedule

Interval	Task	Part Numbers (if needed)
Daily	Check chain tension/sharpness, lubricate bar/chain	STIHL chain oil
10 hours	Clean air filter, check spark plug	1128 140 0603, NGK BPMR7A
50 hours	Replace fuel filter, clean spark arrestor	0000 350 3504
100 hours	Inspect AV system, replace sprocket	1128 007 1003
Annual	Replace fuel lines, check cylinder/piston	1128 358 0500, 1128 358 0700

Note: Service more frequently under heavy use or dusty conditions.

Troubleshooting & Part Replacement

Symptom	Possible Cause	Part Replacement/Corrective Action
Engine won't start	Fuel system, spark plug, ignition	Replace fuel filter (0000 350 3504), spark plug (NGK BPMR7A), check ignition module (1128 400 1405).
Loss of power	Clogged air filter, fuel line, exhaust screen	Clean/replace air filter (1128 140 0603), replace fuel lines (1128 358 0500/0700), clean spark arrestor.
Excessive vibration	Worn AV springs/buffers	Replace AV springs (1128 790 0600/0700) and buffers (1128 790 0800).
Chain won't stay tight	Worn bar, damaged tensioner	Replace guide bar (3003 000 3920), chain tensioner (1128 647 0600).
Oil leakage	Cracked oil tank, seals	Replace oil tank (1128 350 0701), crankshaft seals (1128 084 0800).

Ordering Parts: Use STIHL part numbers. Contact authorized STIHL dealer.

Service Support: 1-800-467-8445; www.stihlusa.com