Stihl HS 74 Manual

The Stihl HS 74 is a professional-grade hedge trimmer designed for demanding trimming and cutting tasks. It features a powerful 2-stroke engine, a robust cutting blade system with dual-sided teeth, anti-vibration handles, a translucent fuel tank, and a lightweight yet durable construction. Below are key sections for safety, features, operation, maintenance, and troubleshooting.

Features at a Glance

Key components: 2-stroke engine, Cutting blade with double-sided teeth, Anti-vibration system, Translucent fuel tank, Throttle trigger lockout, Hand guard, and Shoulder strap attachment point.

Feature	Description
Engine Type	2-stroke, single-cylinder, air-cooled
Cutting Blade Length	24 inches (60 cm) double-sided blade
Anti-Vibration System	Reduces operator fatigue during extended use
Fuel Tank	Translucent for easy fuel level inspection
Throttle Trigger Lockout	Prevents accidental throttle engagement
Hand Guard	Protects hands from debris and branches
Starter	Rewind starter with decompression valve
Weight (without fuel)	Approximately 5.3 kg (11.7 lbs)
Ignition System	Electronic ignition (CDI)
Carburetor	Diaphragm carburetor for consistent performance

Safety Instructions

Read and understand 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: Ensure no bystanders, especially children or pets, are within 15 meters.
3. Inspect Tool: Check for damage, loose parts, and blade condition before each use.
4. Fuel Safety: Refuel outdoors only, with engine off and cool. Use proper fuel mix.
5. Operating Position: Maintain secure footing and balance. Do not operate above shoulder height.

WARNING! Risk of serious injury or death from blade contact, kickback, or flying debris. Never operate with damaged or missing safety devices.

Assembly & Preparation

Unpack and inspect all parts. Assemble handle and attach blade guard if provided.

1. Handle Attachment: Secure the rear handle to the shaft using provided bolts and wrench.
2. Blade Guard: Install the blade guard for transport and storage.
3. Fuel Mix: Prepare fuel mixture of 50:1 (Stihl HP Ultra oil with unleaded gasoline). Shake well.
4. Refueling: Clean area around fuel cap. Fill tank with prepared fuel mix. Wipe any spills.
5. Bar & Chain Oil: Fill the separate oil reservoir with Stihl bar and chain oil (for lubrication system).

CAUTION! Use only Stihl-approved fuel and oil mixtures. Incorrect mixtures can cause engine damage.

Specifications

• Model: Stihl HS 74
• Engine Displacement: 30.1 cm³ (1.84 cu. in.)
• Power Output: 0.9 kW (1.2 hp)
• Cutting Blade Length: 60 cm (24 in)
• Tooth Spacing: 20 mm (0.79 in)
• Max. Cutting Diameter: 20 mm (0.79 in)
• Fuel Tank Volume: 0.55 L (18.6 fl. oz)
• Oil Tank Volume: 0.26 L (8.8 fl. oz)
• Sound Pressure Level: 94 dB(A) (typical)
• Vibration Level (front/rear handle): 4.5/2.5 m/s²
• Warranty: Limited warranty for professional use (see manual).

Controls and Components

Main controls located on the rear handle. Front handle for guidance and stability.

Rear Handle: Throttle trigger, Throttle trigger lockout, Stop switch (I/O), Choke lever, Primer bulb, Fuel tank cap, Oil tank cap.

Front Handle: D-shaped handle with anti-vibration mounts, Hand guard.

Shaft & Engine: Engine housing, Rewind starter, Decompression valve, Muffler, Cutting blade attachment point, Blade lubrication adjustment screw.

Starting & Stopping the Engine

Ensure clear area, secure footing, and blade not touching any object.

1. Cold Start: Move stop switch to "I". Set choke lever to full choke. Press primer bulb 5-10 times. Place unit on firm ground, hold rear handle with left hand, place right foot in handle bracket. Pull starter rope briskly until engine fires. Move choke lever to half-throttle position. Pull starter rope again to start. Allow to warm up at idle.
2. Warm Start: Stop switch "I", choke off. Pull starter rope.
3. Stopping: Release throttle trigger. Move stop switch to "O".

Tip: Do not pull starter rope to full extension or let it snap back.

Operating Instructions

Use smooth, sweeping motions. Let the blade do the work.

1. Grip: Hold front handle with one hand, rear handle with the other. Engage throttle lockout before squeezing throttle.
2. Cutting Technique: Keep blade parallel to hedge surface. Use tip for fine shaping. Avoid twisting blade.
3. Lubrication: Ensure oil reservoir is filled. Adjust oil flow screw if cutting performance decreases.
4. Kickback Awareness: Be aware of blade reaction if it binds or hits a solid object. Release throttle immediately.
5. Fatigue: Take regular breaks due to vibration and weight.

WARNING! Never operate with one hand. Always be aware of the blade position and cutting path.

Maintenance & Cleaning

Perform daily and periodic maintenance. Always disconnect spark plug boot first.

1. Daily: Clean air filter, check for loose fasteners, inspect blade for damage and sharpness, clean exterior.
2. Weekly: Check spark plug condition and gap, clean cooling fins, inspect fuel filter.
3. Blade Care: Sharpen blade regularly with a round file. Lubricate blade rails and pivot points.
4. Fuel System: Drain fuel tank for long storage. Replace fuel filter annually.

CAUTION! Use only Stihl replacement parts. Improper maintenance voids warranty.

Storage

Prepare unit for storage to prevent fuel system damage and corrosion.

1. Run engine dry or add fuel stabilizer to full tank and run for 2 minutes.
2. Clean entire unit thoroughly.
3. Remove spark plug, add a few drops of oil into cylinder, pull starter slowly 2-3 times, reinstall plug.
4. Store in a dry, secure place, out of reach of children, with blade guard installed.

Tip: Store fuel mix in an approved, labeled container for no more than 30 days.

Warranty Information

Stihl Limited Warranty for professional use. Proof of purchase required. Warranty does not cover damage from misuse, neglect, improper fuel, or unauthorized repairs. For warranty service, contact an authorized Stihl servicing dealer. For support, visit www.stihlusa.com or contact customer service at 1-800-467-8445.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine will not start	No fuel, flooded, spark plug faulty	Check fuel level; dry spark plug; check/replace spark plug; ensure choke setting correct.
Engine starts then dies	Clogged fuel filter, dirty air filter, carburetor adjustment	Replace fuel filter; clean air filter; have dealer adjust carburetor.
Loss of power	Clogged air filter, dirty spark arrestor, dull blade	Clean air filter; clean spark arrestor screen; sharpen or replace blade.
Excessive vibration	Loose parts, damaged blade, unbalanced blade	Tighten all fasteners; inspect blade for damage or bends; replace if necessary.
Blade does not cut well	Dull teeth, insufficient lubrication, bent blade	Sharpen teeth; check oil flow and reservoir; inspect blade for straightness.
Oil leaking from unit	Overfilled oil tank, damaged seals	Drain excess oil; inspect for seal damage and have serviced by dealer.

Dealer Service: For repairs beyond basic maintenance, take to an authorized Stihl dealer.

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