Stihl FS 74 Owners Manual

The Stihl FS 74 is a lightweight, professional-grade string trimmer designed for demanding clearing and trimming tasks. It features a powerful 2-stroke engine, the ErgoStart system for easy starting, a loop handle for comfortable two-handed operation, a PolyCut head for efficient line cutting, and a robust gearbox. This manual covers safety, assembly, operation, maintenance, troubleshooting, and specifications to ensure safe and optimal performance.

Features at a Glance

Key components: 2-stroke engine with ErgoStart, loop handle, PolyCut cutting head, robust gearbox, and anti-vibration system.

Feature	Description
Engine	Powerful 2-stroke engine with ErgoStart for easy starting
Handle	Loop handle for secure, two-handed control
Cutting Head	PolyCut head for efficient nylon line cutting
Gearbox	Robust, sealed gearbox for durability
Anti-Vibration	Integrated system to reduce operator fatigue
Throttle Trigger	With throttle trigger lockout for safety
Stop Switch	Easy-access stop switch
Fuel Tank	Transparent for easy fuel level check
Debris Shield	Protects operator from thrown debris
Spark Plug	Accessible for maintenance

Safety Instructions

Read and understand all instructions before use. Wear appropriate PPE.

1. Personal Protective Equipment (PPE): Always wear safety glasses, hearing protection, sturdy gloves, long pants, and closed-toe shoes.
2. Work Area Safety: Clear area of bystanders, especially children and pets. Be aware of hidden obstacles like wires or rocks.
3. Fuel Safety: Refuel outdoors, with engine off and cool. Use approved fuel containers. Wipe up spills immediately.
4. Operation Safety: Hold unit firmly with both hands. Do not operate in poor lighting or bad weather. Never cut near flammable materials.

WARNING! Failure to follow safety instructions can result in serious injury or death. The cutting tool continues to rotate after the throttle is released.

Assembly & Preparation

Unpack all parts. Assemble handle, attach cutting head, and add fuel/oil mixture.

1. Handle Assembly: Attach the loop handle to the shaft at the desired position and tighten securely.
2. Cutting Attachment: Install the PolyCut head or other approved attachment according to the separate assembly sheet. Ensure it is locked properly.
3. Debris Shield: Attach the debris shield to the shaft above the cutting head.
4. Fuel Mix: Prepare a 50:1 mixture of unleaded gasoline (min. 89 octane) and STIHL 2-stroke engine oil. Fill the fuel tank.

CAUTION! Use only STIHL-approved attachments. Incorrect assembly can lead to failure and injury.

Specifications

• Engine Type: Single cylinder, 2-stroke, air-cooled.
• Displacement: [e.g., 27.2 cc] (Refer to your unit's specific data).
• Power Output: [e.g., 0.9 kW / 1.2 bhp].
• Fuel/Oil Ratio: 50:1 (STIHL 2-stroke oil).
• Fuel Tank Capacity: [e.g., 0.53 liters].
• Sound Pressure Level: [e.g., 96 dB(A)] - Wear hearing protection.
• Vibration Level: [e.g., 4.5 m/s²] - Anti-vibration system included.
• Cutting Attachment: Standard PolyCut head. Compatible with other STIHL trimmer heads and blades.
• Warranty: Limited warranty period. See dealer for details.

Controls and Components

Main controls located on the handle and engine housing.

Handle Area: Throttle trigger, throttle trigger lockout, stop switch.

Engine Housing: ErgoStart starter grip, choke lever, air filter cover, spark plug, fuel tank cap.

Shaft: Gearbox, attachment point for cutting head, debris shield mount.

Operation: Press throttle lockout to enable throttle. Squeeze throttle to increase engine speed. Release throttle and press stop switch to stop engine.

Fuel & Lubrication

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

1. Use a clean, approved fuel can. Mix fuel and oil thoroughly before filling.
2. Fill fuel tank to just below the rim. Tighten cap securely.
3. Gearbox Lubrication: The gearbox is filled with grease at the factory. Under normal use, no additional lubrication is required.
4. Never use: Straight gasoline, automotive oil, old or stale fuel mixture, or fuel with more than 10% ethanol.

Tip: Use STIHL MotoMix pre-mixed fuel for optimum performance and to avoid fuel-related issues.

Starting & Operation

Follow cold or warm starting procedure.

1. Cold Start: Place unit on clear, flat ground. Set choke lever to closed position (✱). Press fuel pump bulb 5+ times. Press throttle trigger lockout and squeeze throttle trigger once to set start throttle. Pull starter rope sharply until engine fires. Move choke lever to open position (○). Pull starter rope again to start. Allow brief warm-up.
2. Warm Start: Choke lever in open position (○). Pull starter rope to start.
3. Operation: Hold unit with both hands. Use a smooth, sweeping motion from right to left for cutting. Let the tool do the work; avoid forcing it.
4. Stopping: Release throttle trigger. Press and hold the stop switch until the engine stops.

WARNING! Keep hands and feet away from the cutting attachment at all times, especially while starting and running.

Cutting Attachments

Primarily designed for use with the PolyCut nylon line head.

1. Line Advance: Tap the head on the ground while at high RPM (Bump Feed) to advance fresh line.
2. Replacing Line: Remove spool, wind new line following direction arrows, feed ends through eyelets, reassemble.
3. Alternative Attachments: Can use other STIHL trimmer heads or metal blades (e.g., circular grass blade) for heavy brush. Ensure correct installation kit is used.
4. Inspection: Regularly check cutting attachment for wear, damage, or loose parts. Replace worn line or damaged parts immediately.

CAUTION! Use only STIHL-approved cutting attachments. Improper attachments can cause loss of control and injury.

Maintenance & Storage

Regular maintenance ensures long life and safe operation.

Daily/Before Use: Check for loose nuts/bolts, inspect cutting attachment, check fuel level.

Cleaning: Keep unit clean, especially cooling fins and air filter area. Use a brush or cloth.

Air Filter: Clean regularly. Remove cover, take out filter, tap clean or wash in soapy water. Dry completely before reinstalling.

Spark Plug: Check and clean electrode periodically. Replace if worn or damaged. Gap: 0.5 mm (0.020").

Storage (over 30 days): Drain fuel tank completely or add fuel stabilizer. Run engine until it stops to clear carburetor. Clean entire unit. Store in a dry, secure place.

CAUTION! Always disconnect the spark plug boot before performing any maintenance except refueling.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine will not start	No fuel, flooded, spark plug faulty, choke position wrong	Check fuel, wait if flooded, check/clean spark plug, ensure correct choke setting.
Engine runs poorly or stalls	Dirty air filter, old fuel, clogged fuel filter	Clean/replace air filter, use fresh fuel mix, replace fuel filter in tank.
Excessive vibration	Damaged cutting attachment, loose parts	Inspect attachment for damage/balance, tighten all nuts and bolts.
Line does not advance	Empty spool, tangled line, worn head	Refill line spool, rewind line correctly, replace head if worn out.
Loss of power	Clogged muffler screen, carbon buildup	Clean spark arrestor screen (dealer service).

Note: For complex repairs, take your STIHL FS 74 to an authorized STIHL servicing dealer.

Warranty & Service

Your STIHL FS 74 is covered by a limited warranty. Proof of purchase from an authorized STIHL dealer is required.

Warranty Service: Contact the authorized STIHL dealer where you purchased the unit for warranty claims and service.

Parts & Accessories: Use only genuine STIHL replacement parts and accessories to maintain performance, safety, and warranty coverage.

For Support: Visit the official STIHL website at www.stihl.com or contact your local authorized STIHL dealer.

Disposal: At end of life, do not dispose with household waste. Take to an authorized recycling center or return to your STIHL dealer.