Stihl MS 390 Parts Manual

The Stihl MS 390 is a professional-grade chainsaw featuring a powerful engine, robust construction, and advanced safety features. This parts manual provides detailed diagrams, part numbers, and ordering information for all components of the MS 390 chainsaw, including the engine assembly, cutting equipment, fuel system, ignition system, and housing. Below are key sections for identification, assembly groups, exploded views, ordering, and maintenance.

1. Identification & Specifications 2. Safety Components 3. Engine Assembly 4. Fuel System 5. Ignition System 6. Cutting Equipment 7. Housing & Covers 8. Fasteners & Hardware 9. Ordering Parts 10. Assembly Diagrams 11. Maintenance Schedule

Identification & Specifications

Key identifiers: Model number MS 390, serial number location on crankcase. Engine: 2-stroke, single cylinder, air-cooled. Displacement: 64.1 cc. Power output: 3.6 kW (4.9 hp). Weight (without cutting equipment): 6.2 kg. Fuel/oil mixture: 50:1 (STIHL HP Ultra oil). Bar length range: 40 cm (16") to 50 cm (20"). Chain pitch: 3/8" or .325".

Feature	Description
Engine Type	2-stroke, single cylinder
Displacement	64.1 cc
Power Output	3.6 kW (4.9 hp)
Fuel Capacity	550 ml
Oil Tank Capacity	260 ml
Ignition System	Electronic, capacitor discharge (CDI)
Chain Brake	Inertia-activated
Starter	STIHL ErgoStart (optional)
Vibration Damping	Anti-vibration system
Sound Pressure Level	Typically 112 dB(A)

Safety Components

Critical safety parts for operator protection and saw integrity.

Chain Brake Assembly: Includes brake band, handle, and activation mechanism.
Throttle Lockout: Prevents accidental throttle engagement.
Right Hand Guard: Protects hand from chain breakage.
Chain Catcher: Stops broken chain from hitting operator.
Muffler with Spark Arrestor: Reduces exhaust sparks.

WARNING! Always use genuine STIHL safety parts. Never operate with damaged or missing safety components.

Engine Assembly

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

Cylinder: Part number 1128 020 2001. Includes cylinder, decompression valve port.
Piston: Part number 1128 030 2001. 46 mm diameter, with rings.
Crankshaft: Part number 1128 040 2001. Integrated crank pins and main bearings.
Crankcase: Part number 1128 050 2001. Upper and lower halves.
Bearings & Seals: Main bearings, crankshaft seals, wrist pin bearing.

CAUTION! Engine assembly requires special tools and expertise. Consult a STIHL servicing dealer.

Fuel System

Fuel Tank: Part number 1128 350 2001. Includes cap and vent.
Carburetor: Zama C1Q-S267 or equivalent. Includes diaphragm, gaskets, needles.
Fuel Filter: Part number 0000 350 3501. In-tank type.
Fuel Lines: Supply and return lines, primer bulb lines (if equipped).
Air Filter: Part number 0000 120 1625. Pre-cleaner available.
Impulse Line: Connects crankcase to carburetor.

Ignition System

Ignition module (coil), spark plug, stop switch, wiring harness.

Ignition Module: Part number 1128 400 2001. CDI unit, mounted on fan housing.

Spark Plug: Bosch WSR 6 F or equivalent, gap 0.5 mm.

Stop Switch: Part number 1128 410 2001. Grounds ignition to stop engine.

Wiring: Harness connecting coil, switch, and optional ErgoStart.

Cutting Equipment

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

Guide Bar: STIHL Rollomatic E or ES. 40cm to 50cm lengths.
Saw Chain: STIHL Oilomatic. 3/8" PMN or .325" PM.
Sprocket: Rim sprocket system, part number depends on pitch.
Clutch: Centrifugal, part number 1128 160 2001.
Chain Tensioner: Screw-type, located on side cover.

Tip: Always match chain pitch and gauge to bar. Keep chain sharp and properly tensioned.

Housing & Covers

Plastic housing components, covers, handles, and AV mounts.

Fan Housing: Part number 1128 880 2001. Covers cylinder and flywheel.
Chain Brake Cover: Part number 1128 891 2001. Includes hand guard.
Fuel Tank Housing: Part number 1128 850 2001. Integrated with rear handle.
Anti-Vibration Elements: Rubber mounts between engine and housing.
Handle: Front and rear handles, with heating element option.

WARNING! Cracked housing can compromise safety. Replace damaged housing immediately.

Fasteners & Hardware

Screws, nuts, washers, clips specific to MS 390 assembly.

Bar nuts, chain cover screws, housing screws, carburetor screws, muffler screws, etc. Refer to diagrams for exact part numbers and quantities.

Ordering Parts

Use the part numbers listed in this manual. Contact an authorized STIHL dealer.

CAUTION! Use only genuine STIHL parts to ensure performance, safety, and warranty compliance.

Assembly Diagrams

Exploded views showing part relationships and numbers for major groups: Engine, Fuel System, Ignition, Cutting Attachment, Housing. (Note: In a full manual, detailed diagrams would be inserted here).

Maintenance Schedule

Component	Interval	Action / Part to Check
Air Filter	Daily / 10 hrs	Clean; replace if damaged. Part #0000 120 1625.
Spark Plug	100 hrs	Clean, re-gap, or replace. Bosch WSR 6 F.
Fuel Filter	Yearly / 100 hrs	Replace. Part #0000 350 3501.
Sprocket	Seasonal / Chain Change	Inspect; replace rim if worn.
Chain Brake	Before each use	Test function; replace band if worn.
Bar & Chain	Daily	Sharpen chain, clean bar groove, check wear.
Anti-Vibration Elements	Yearly	Inspect for cracks/deterioration.
Cylinder Fins / Muffler	25 hrs	Clean of carbon and debris.

Service: For major repairs, contact an authorized STIHL servicing dealer.

Support: www.stihl.com or your local STIHL dealer.