The STIHL MS660 is a professional-grade chainsaw designed for heavy-duty felling, limbing, and bucking applications. This parts manual provides detailed information on the components, assembly, maintenance, and replacement parts for the MS660 model. Below are key sections covering identification, engine components, fuel system, ignition system, cutting equipment, maintenance procedures, and ordering information.
Key identifiers: Model number MS660, serial number location on crankcase, engine displacement, power output, and weight.
| Feature | Description |
|---|---|
| Engine Displacement | 91.6 cc (5.59 cu. in.) |
| Power Output | 7.4 bhp (5.5 kW) |
| Fuel Tank Capacity | 825 ml (27.9 fl. oz.) |
| Oil Tank Capacity | 410 ml (13.9 fl. oz.) |
| Weight (powerhead only) | 8.6 kg (19.0 lbs) |
| Guide Bar Length Range | 50 cm (20") to 105 cm (41") |
| Chain Pitch/Gauge | .404" / .063" (standard) |
| Ignition System | Electronic, capacitor discharge |
| Carburetor | STIHL HD-12 |
| Recommended Fuel | Minimum 89 octane, mixed with STIHL oil |
Major engine groups: Crankcase, cylinder, piston, crankshaft, connecting rod, bearings, seals.
WARNING! Engine components are heavy and precise; handle with care to avoid damage or injury. Use proper tools for disassembly.
Components: Fuel tank, cap, filter, lines, carburetor, primer bulb, throttle linkage.
CAUTION! Always drain fuel before servicing fuel system. Use STIHL-approved fuel lines to prevent deterioration.
Components: Guide bar, saw chain, drive sprocket, chain tensioner, bar nuts, clutch cover.
Guide Bar: Roller-nose or solid-nose, various lengths, groove width .063". Chain: .404" pitch, round-chisel or semi-chisel, number of drive links varies by bar length. Sprocket: Rim or spur type, part numbers. Tensioner: Screw adjustment, pinion, and slide parts. Clutch Cover: With chain brake, hand guard, and deflection spikes.
Air filter assembly: Filter element, cover, pre-cleaner, and retaining clips.
Tip: Service air filter regularly in dusty conditions to maintain engine performance and life.
Supports manual recoil starting.
WARNING! Recoil spring is under tension; disassemble with caution using proper tools to prevent injury.
Clutch Assembly: Drum, shoes, springs, retaining ring. Sprocket: Rim type part numbers, bearing. Drive Shaft: Output shaft, seal, and bearing.
Includes crankcase halves, gaskets, cylinder, piston, rings, wrist pin, bearings, seals.
CAUTION! Use torque wrench for case screws. Ensure proper seal installation to prevent air leaks.
Daily: Check chain tension, sharpness, lubrication. Clean air filter, check for loose fasteners. Weekly: Clean cooling fins, inspect spark plug, fuel filter. Monthly: Check clutch, sprocket, anti-vibration elements. Annually: Replace fuel lines, inspect crankshaft seals, decarbonize muffler.
| Symptom | Possible Part Needed | Part Number Example |
|---|---|---|
| Engine won't start, no spark | Ignition module | 1140 400 1301 |
| Loss of power, hard starting | Piston & cylinder kit | 1128 030 2003 |
| Fuel leak from carburetor | Carburetor repair kit | 1128 007 1060 |
| Chain won't stay tight | Bar tensioner assembly | 1140 647 7700 |
| Starter rope broken | Starter rope kit | 1118 850 4800 |
Ordering: Use serial number and illustrated parts list for accurate part identification.
Service: Contact authorized STIHL dealer or visit www.stihlusa.com for parts and support.