Stihl HS81R Hedge Trimmer Manual

The Stihl HS81R is a professional-grade, double-sided hedge trimmer featuring a powerful gasoline engine, 31.5-inch double-sided cutting blade, anti-vibration system, and ergonomic handles for extended use. It is designed for heavy-duty trimming and shaping of hedges and shrubs. Below are key sections for safety, features, operation, maintenance, and troubleshooting.

Features at a Glance

Key components: 2-stroke gasoline engine, double-sided cutting blade, anti-vibration system, rear handle with throttle trigger and lockout, front handle, fuel tank, and muffler.

Safety Information

Read all instructions before operation. Wear appropriate PPE.

1. Personal Protective Equipment: Always wear safety glasses, hearing protection, gloves, long pants, and sturdy boots.
2. Clear Work Area: Remove debris, stones, and metal objects from trimming area.
3. Inspect Tool: Check for loose parts, damaged blade, or leaks before each use.
4. Fuel Safety: Refuel in well-ventilated area, engine off and cool. No smoking.
5. Two-Hand Operation: Always grip front and rear handles during operation.

WARNING! Risk of severe injury from cutting blade. Keep hands and feet away. Do not operate near power lines.

Assembly & Preparation

Unpack and inspect contents. Assemble handle and attach blade guard if provided.

1. Attach handle: Secure front and rear handles as per instructions.
2. Install blade guard: For storage and transport.
3. Fuel mixture: Prepare 50:1 gasoline to 2-stroke oil mix (use STIHL HP Ultra or equivalent).
4. Fill tanks: Add fuel mix to fuel tank and bar & chain oil to oil tank.

CAUTION! Use only recommended oil. Incorrect mixture can cause engine damage.

Specifications

• Model: HS81R
• Engine Displacement: 1.6 cu in (27.2 cc)
• Power Output: Professional-grade power for heavy-duty trimming
• Cutting Length: 31.5 inches (80 cm)
• Tooth Spacing: 0.8 inches (20 mm)
• Weight: Approx. 13.7 lbs (6.2 kg) without fuel
• Fuel/Oil Ratio: 50:1 (Gasoline : 2-stroke engine oil)
• Vibration Damping: Advanced anti-vibration system
• Sound Level: Complies with relevant directives
• Warranty: Refer to STIHL warranty terms

Controls and Operation

Master control lever: Combines stop switch and choke functions. Throttle trigger: Located on rear handle with lockout. Throttle latch: For starting. Decompression valve: Eases starting.

Operation: Press throttle lockout and squeeze throttle trigger to increase engine speed. Release throttle trigger to idle. Use master control lever for stop/choke.

Blade lubrication is automatic via oil pump. Adjust oil flow if needed via screw (consult dealer).

Fuel & Oil Mixture

Use fresh, unleaded gasoline (min. 89 octane) mixed with high-quality 2-stroke engine oil (STIHL HP Ultra recommended).

1. Mix ratio: 50:1 (2.6 oz oil per 1 gallon gasoline).
2. Mix in approved container, not inside fuel tank.
3. Shake gently before refueling.
4. Fill fuel tank to 80% capacity to allow for expansion.

Tip: Never use automotive oil, diesel, or old gasoline. Discard fuel mix after 30 days.

Starting & Stopping

Starting (Cold Engine):

1. Press fuel pump bulb 5-10 times until firm.
2. Set master control lever to choke position (full left).
3. Press decompression valve (if equipped).
4. Place on firm ground, hold rear handle with right hand, front handle with left.
5. Pull starter rope briskly until engine fires.
6. Move master control lever to half-throttle position.
7. Pull starter rope again to start engine.
8. Allow to warm up at idle for 30 seconds.

Stopping: Release throttle, move master control lever to STOP position.

WARNING! Keep clear of blade during starting. Ensure secure footing.

Cutting Techniques

For best results and safety:

1. Hold trimmer with both hands, blade parallel to ground.
2. Use smooth, sweeping motions from bottom to top.
3. Cut sides first, then top for even shape.
4. Allow blade to reach full speed before cutting.
5. Avoid cutting stems thicker than 3/8 inch (10 mm).
6. Do not force tool; let blade do the work.
7. Periodically clean blade of sap and debris.

CAUTION! Do not use for cutting grass, weeds, or non-woody plants.

Maintenance & Cleaning

Daily maintenance ensures long life.

1. Air filter: Clean regularly; replace if damaged.
2. Spark plug: Check gap (0.020 inches / 0.5 mm); replace annually.
3. Blade: Inspect for damage, sharpen or replace as needed.
4. Lubrication: Keep oil tank filled with STIHL bar & chain oil.
5. Exterior: Wipe clean with damp cloth after use.

CAUTION! Disconnect spark plug wire before performing maintenance.

Storage

For storage longer than 30 days:

1. Drain fuel tank and run engine until it stops.
2. Remove spark plug, add 1 teaspoon of oil, pull starter 2-3 times, reinstall plug.
3. Clean entire unit, especially blade and cooling fins.
4. Store in dry, locked area out of reach of children.
5. Protect blade with guard or sheath.

WARNING! Gasoline left in tank can degrade and damage engine components.

Troubleshooting

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

Support: Visit www.stihlusa.com or call 1-800-467-8445 for dealer locations and manuals.