STIHL HS81R Manual

The STIHL HS81R is a professional-grade hedge trimmer featuring a powerful 2-stroke engine, double-sided cutting blades, anti-vibration system, ErgoStart™ technology for easy starting, STIHL QuickStop® inertia chain brake, and a lightweight yet durable construction. Designed for demanding trimming tasks, it offers precision cutting with reduced operator fatigue. Below are key sections for safety, features, operation, maintenance, and troubleshooting.

Features at a Glance

Key components: 2-stroke engine, double-sided cutting blade, anti-vibration system, ErgoStart™, QuickStop® inertia chain brake, throttle trigger lockout, and shoulder strap attachment points.

Feature	Description
Engine Type	2-stroke, single-cylinder, air-cooled
Cutting Blade Length	24 inches (600 mm) double-sided
Anti-Vibration System	Reduces operator fatigue during extended use
ErgoStart™	Simplified starting mechanism
QuickStop® Inertia Chain Brake	Stops cutting blade rapidly in case of kickback
Throttle Trigger Lockout	Prevents accidental throttle engagement
Shoulder Strap Attachment	For comfortable carrying and operation
Fuel Tank Capacity	Approx. 0.95 liters (1.0 US qt)
Oil Tank Capacity	Approx. 0.25 liters (0.26 US qt)
Weight (without fuel)	Approx. 5.5 kg (12.1 lbs)

Safety Information

Read and understand all safety instructions before operation.

1. Wear protective gear: safety glasses, hearing protection, gloves, sturdy boots, long pants.
2. Clear work area of bystanders, especially children and pets.
3. Inspect tool before each use: check for damage, loose parts, and blade condition.
4. Never operate with damaged or missing safety devices.
5. Keep hands and feet away from cutting blades at all times.

WARNING! Risk of serious injury or death from kickback, blade contact, or improper use. Always hold trimmer firmly with both hands.

Assembly & Preparation

Unpack and inspect contents. Assemble handle and cutting blade.

1. Attach handle: Align with mounting points, secure with provided bolts.
2. Install cutting blade: Ensure blade is properly seated and tightened.
3. Fuel mixture: Use STIHL 2-stroke engine oil mixed with unleaded gasoline (50:1 ratio).
4. Fill fuel and oil tanks: Use clean, approved containers.
5. Adjust shoulder strap: For comfortable operation and weight distribution.

CAUTION! Use only STIHL-approved fuel and lubricants. Do not use automotive oil or alternative fuels.

Technical Specifications

• Model: HS81R Professional Hedge Trimmer
• Engine Displacement: 27.2 cm³ (1.66 cu. in.)
• Power Output: 0.9 kW (1.2 hp)
• Cutting Blade Length: 600 mm (24 in)
• Tooth Spacing: 20 mm (0.79 in)
• Maximum Cutting Diameter: 20 mm (0.79 in)
• Fuel/Oil Ratio: 50:1 (STIHL 2-stroke oil)
• Sound Pressure Level: 94 dB(A)
• Vibration Level: 4.5 m/s² (front handle)
• Warranty: 1 year commercial use, 2 year private use

Controls and Operation

Main controls: Throttle trigger, throttle trigger lockout, stop switch, choke lever, primer bulb.

Starting Procedure:

1. Place trimmer on clear, level surface.
2. Set stop switch to "I" (run) position.
3. Press and hold throttle trigger lockout while squeezing throttle trigger.
4. Set choke lever to cold start position (if engine is cold).
5. Press primer bulb 5-10 times until fuel is visible.
6. Pull starter rope briskly until engine fires.
7. Move choke lever to run position once engine starts.
8. Allow engine to warm up at idle for 30 seconds.

Operating Tips: Maintain firm grip, use smooth sweeping motions, avoid cutting above shoulder height.

Fuel & Lubrication

Use fresh unleaded gasoline (minimum 89 octane) mixed with STIHL 2-stroke oil at 50:1 ratio.

1. Mix fuel in approved container: Add oil first, then gasoline.
2. Shake container thoroughly before refueling.
3. Fill fuel tank to 80% capacity to allow for expansion.
4. Check and fill blade lubrication oil before each use.
5. Clean fuel cap area before opening to prevent contamination.

Tip: Never use fuel older than 30 days. Store fuel in approved containers away from heat sources.

Maintenance Procedures

Regular maintenance ensures optimal performance and longevity.

1. Daily: Clean air filter, check blade sharpness and tension.
2. Weekly: Inspect spark plug, clean cooling fins, check all fasteners.
3. Monthly: Clean fuel filter, check fuel lines, inspect anti-vibration elements.
4. Seasonally: Replace spark plug, clean carburetor, sharpen cutting blades.
5. Blade sharpening: Use proper file size, maintain original angle.

WARNING! Always disconnect spark plug wire before performing maintenance. Allow engine to cool completely.

Storage Guidelines

Proper storage prevents fuel system damage and corrosion.

1. Drain fuel tank completely or add fuel stabilizer.
2. Run engine until it stops to clear carburetor of fuel.
3. Clean entire unit thoroughly, especially cutting blades.
4. Apply light oil to cutting blades to prevent rust.
5. Store in dry, secure location away from children.

CAUTION! Never store with fuel in tank for more than 30 days without stabilizer.

Warranty Information

STIHL Limited Warranty: 1 year for commercial use, 2 years for private use from date of purchase. Warranty covers defects in materials and workmanship. Not covered: normal wear, misuse, improper maintenance, unauthorized repairs. For warranty service, contact authorized STIHL dealer with proof of purchase. For support, visit www.stihlusa.com or contact 1-800-467-8445.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine won't start	Fuel issues, spark plug	Check fuel mixture, spark plug condition, air filter. Ensure choke is set correctly.
Engine runs poorly	Clogged filter, carburetor	Clean or replace air filter. Check fuel filter and carburetor settings.
Excessive vibration	Loose parts, blade damage	Tighten all fasteners. Inspect cutting blade for damage or imbalance.
Blade doesn't cut well	Dull blade, improper tension	Sharpen cutting teeth. Adjust blade tension according to specifications.
Overheating	Clogged cooling fins, lean mixture	Clean cooling fins. Check fuel mixture and carburetor adjustment.

Service: For repairs beyond basic maintenance, contact authorized STIHL dealer.

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