STIHL HS 80 Workshop Manual
The STIHL HS 80 is a professional-grade hedge trimmer designed for demanding tasks. This workshop manual provides comprehensive technical information for maintenance, repair, and troubleshooting. It covers the engine, cutting system, fuel system, ignition, and all major components. Below are key sections for safety, specifications, maintenance procedures, disassembly/assembly, troubleshooting, and parts identification.
Features at a Glance
Key components: Two-stroke engine, double-sided cutting blade with laser-cut teeth, anti-vibration system, STIHL QuickStop® inertia chain brake, ErgoStart™ system, and tool-free air filter access.
| Feature | Description |
|---|
| Engine Type | STIHL single-cylinder two-stroke engine |
| Displacement | 27.2 cm³ (1.66 cu. in.) |
| Power Output | 0.8 kW (1.1 hp) |
| Cutting System | Double-sided blade, 600 mm (24 in.) length |
| Tooth Spacing | 20 mm (0.79 in.) |
| Weight (without cutter bar) | Approx. 5.2 kg (11.5 lbs) |
| Fuel Tank Capacity | 0.5 litres (16.9 fl. oz.) |
| Oil Tank Capacity | 0.25 litres (8.5 fl. oz.) |
| Anti-Vibration System | Integrated dampers in handles and engine mounts |
| Safety Features | STIHL QuickStop®, front hand guard, throttle trigger lockout |
Safety Precautions
Always prioritize safety when performing maintenance or repairs. Disconnect the spark plug boot before any work.
- Personal Protective Equipment (PPE): Always wear safety glasses, gloves, hearing protection, and sturdy footwear.
- Work Area: Work in a clean, well-ventilated area away from ignition sources. Keep the workspace free of fuel and oil spills.
- Fuel Safety: Drain fuel tank before major disassembly. Use only STIHL MotoMix® or a 50:1 mixture of high-quality gasoline and STIHL HP Ultra oil.
- Sharp Components: The cutting blade is extremely sharp. Handle with care and always wear cut-resistant gloves.
- Torque Specifications: Use a torque wrench for all critical fasteners (e.g., cylinder head, clutch). Overtightening can cause damage.
WARNING! Failure to follow safety instructions can result in serious injury or death. This manual is for qualified technicians only.
Technical Specifications
- Model: STIHL HS 80
- Engine: Air-cooled, single-cylinder two-stroke
- Idle Speed: 2,800 rpm
- Maximum Power Speed: 9,500 rpm
- Ignition System: Electronic, capacitor discharge ignition (CDI)
- Spark Plug: Bosch WSR 6 F or equivalent, gap 0.5 mm (0.020 in.)
- Carburetor: Zama C1Q-S series, adjustable (H, L, LA)
- Fuel/Oil Ratio: 50:1 (STIHL HP Ultra)
- Clutch: Centrifugal, engagement speed approx. 2,800 rpm
- Vibration Levels (front/rear handle): According to ISO 22867
- Sound Pressure Level: According to ISO 22868
Maintenance Schedule
Regular maintenance is crucial for performance, longevity, and safety. Follow this schedule based on hours of operation or as needed.
| Component / Task | Before Each Use | Every 10 Hours | Every 50 Hours | Every 100 Hours / Season |
|---|
| Check for loose fasteners | ✓ | | | |
| Clean air filter | | ✓ | | |
| Replace air filter | | | ✓ | |
| Check/replace spark plug | | | ✓ | |
| Clean spark arrestor screen (if equipped) | | | ✓ | |
| Clean cooling fins | | | ✓ | |
| Inspect fuel filter & lines | | | | ✓ |
| Inspect/replace cutter bar lubrication wicks | | ✓ | | |
| Sharpen/inspect cutting blade | ✓ | | ✓ | |
| Check anti-vibration elements | | | | ✓ |
| Clean carburetor (external) | | | ✓ | |
Engine System
Includes cylinder, piston, crankshaft, connecting rod, and bearings.
- Cylinder & Piston Inspection: Remove muffler to inspect piston and cylinder through exhaust port. Look for scoring, scratches, or excessive carbon buildup.
- Compression Test: Use a compression gauge. Minimum acceptable compression is typically above 110 psi. Low compression indicates worn piston rings, cylinder, or a leaking crank seal.
- Crankcase Pressure/Vacuum Test: Required after any engine disassembly to check for air leaks at crankshaft seals and gaskets.
- De-Carbonizing: Remove cylinder head and clean combustion chamber and piston crown of carbon deposits.
Torque Specs (typical): Cylinder head bolts: 20 Nm (14.8 ft-lb). Spark plug: 25 Nm (18.4 ft-lb).
Cutting System
Comprises the double-sided blade, blade carrier, gear drive, and lubrication system.
- Blade Removal: Remove the blade retaining nuts and washers. Carefully slide the blade off the guide bar.
- Blade Sharpening: Use a flat file. Maintain the original cutting angle (approx. 45°). File all teeth to an equal length. Do not file the depth gauges (rakers).
- Blade Carrier & Gear Inspection: Check for worn or damaged gear teeth on the blade carrier and the drive gear from the engine. Replace if chipped or excessively worn.
- Lubrication System: Ensure the oil passages in the guide bar are clear. Check the manual oil pump (if equipped) and the automatic oiler feed rate. Replace lubrication wicks as per maintenance schedule.
- Blade Installation: Apply a thin coat of grease to the guide bar. Reinstall blade, ensuring proper orientation. Tighten nuts evenly to specified torque.
CAUTION! Always wear heavy-duty gloves when handling the cutting blade.
Fuel System & Carburetor
Includes fuel tank, filter, lines, primer bulb, and Zama carburetor.
- Fuel Line Replacement: Drain tank. Remove old lines from tank fittings and carburetor. Cut new fuel line to length and press firmly onto fittings. Ensure no kinks.
- Fuel Filter: Replace if clogged or during scheduled maintenance. Attach to the end of the fuel line inside the tank.
- Carburetor Adjustment (Basic): Initial settings: L screw = 1 turn open, H screw = 1 turn open, LA (idle) screw = 1 turn open. Fine-tune with engine at operating temperature.
- L (Low Speed): Adjust for smooth acceleration from idle.
- H (High Speed): Adjust for maximum RPM without exceeding factory spec (use tachometer).
- LA (Idle): Adjust for stable idle just above clutch engagement speed.
- Carburetor Diaphragm & Gasket Kit: If engine runs poorly (lean/rich), rebuild carburetor using a genuine STIHL repair kit. Replace all diaphragms, gaskets, and the needle valve.
Ignition System
Electronic CDI module, spark plug, boot, and stop switch.
- Spark Test: Remove spark plug, reconnect boot, and ground plug base against cylinder. Pull starter cord. Look for strong blue spark. No spark indicates faulty module, boot, or stop switch wire.
- Ignition Module Air Gap: Gap between module flywheel magnets and coil legs should be 0.3 mm (0.012 in.). Use a feeler gauge. Adjust by loosening module mounting screws.
- Stop Switch Test: Disconnect the stop switch wire from the module. If spark returns, the stop switch or wire is shorted.
- Spark Plug: Check electrode gap (0.5 mm). Replace if electrodes are eroded or insulator is cracked/fouled.
Disassembly & Assembly
Major procedure overview. Refer to detailed diagrams for step-by-step guidance.
- Preparation: Drain all fuel and oil. Clean exterior thoroughly. Document wire and cable routing with photos.
- Remove External Components: Remove starter assembly, air filter cover, filter, and carburetor cover. Disconnect fuel lines and throttle linkage.
- Separate Engine from Housing: Remove all screws connecting the engine/powerhead to the main housing and rear handle. Note locations of anti-vibration mounts and spacers.
- Engine Disassembly: Remove clutch, fan wheel, and ignition module to access crankshaft. Split crankcase using a case splitter tool. Remove crankshaft, bearings, and seals.
- Reassembly: Reverse order. Use new gaskets and seals. Apply thread locker to critical fasteners. Perform crankcase pressure/vacuum test after assembly.
Note: Specialized tools (clutch holder, flywheel puller, case splitter) are required for engine work.
Troubleshooting
| Symptom | Possible Cause | Corrective Action |
|---|
| Engine will not start | 1. No spark
2. No fuel
3. Flooded | 1. Check spark plug, boot, ignition module, stop switch.
2. Check fuel tank, lines, filter, carburetor diaphragm.
3. Remove plug, dry it, pull starter with throttle open. |
| Engine starts but dies | 1. Clogged fuel filter/vent
2. Faulty carburetor
3. Air leak | 1. Replace fuel filter, clear tank vent.
2. Clean/rebuild carburetor.
3. Perform crankcase pressure test. |
| Loss of power | 1. Clogged air filter
2. Exhaust port blocked
3. Worn piston/cylinder | 1. Clean/replace air filter.
2. Clean spark arrestor and muffler.
3. Inspect through exhaust port; measure compression. |
| Excessive vibration | 1. Unbalanced/damaged blade
2. Worn anti-vibration mounts
3. Loose engine mounts | 1. Inspect, sharpen, or replace blade.
2. Replace anti-vibration elements.
3. Tighten all engine housing screws to spec. |
| Blade does not move or is sluggish | 1. Clutch worn/glazed
2. Gear teeth damaged
3. Blade binding | 1. Inspect clutch shoes and drum; replace if worn.
2. Inspect drive gear and blade carrier gear.
3. Clean and lubricate blade guide bar; check for bends. |
| Oil leaking excessively | 1. Oiler setting too high
2. Damaged oil lines
3. Faulty oil pump | 1. Adjust oiler feed rate screw.
2. Inspect and replace oil lines.
3. Check and replace oil pump if defective. |
Parts List & Diagrams
Refer to the official STIHL Illustrated Parts Diagram (IPD) for the HS 80 for exact part numbers and exploded views. Major groups include:
- Group 1: Housing, handles, and anti-vibration system.
- Group 2: Engine assembly (crankcase, cylinder, piston, crankshaft).
- Group 3: Fuel system (tank, cap, lines, carburetor).
- Group 4: Ignition system (module, flywheel, spark plug).