Stihl S10 Manual

The Stihl S10 is a professional-grade, lightweight, and versatile string trimmer/brushcutter designed for demanding landscaping and clearing tasks. It features a powerful 2-stroke engine, the innovative Easy2Start™ system, the ErgoStart™ decompression valve, an anti-vibration system, a translucent fuel tank, a semi-automatic tapeless line advance (C5-2), and a robust cutting head. Below are key sections for safety, features, assembly, operation, maintenance, and troubleshooting.

Features at a Glance

Key components: 2-stroke engine with Easy2Start™, ErgoStart™ decompression valve, anti-vibration system, translucent fuel tank, semi-automatic tapeless line advance (C5-2), harness attachment points, and throttle trigger lockout.

Feature	Description
Easy2Start™ System	Reduces pulling force required for starting by up to 30%
ErgoStart™ Decompression Valve	Reduces compression for easier starting
Anti-Vibration System	Reduces operator fatigue during extended use
Translucent Fuel Tank	Allows for easy visual check of fuel level
C5-2 Tapeless Line Advance	Semi-automatic bump-feed cutting head for easy line extension
Throttle Trigger Lockout	Prevents accidental throttle activation
Harness Attachment Points	For comfortable use with a shoulder or harness system
Spark Arresting Muffler	Standard for safe operation in dry conditions
Decompression Valve Button	Manual override for starting in cold conditions
Stop Switch	Immediately stops the engine

Safety Information

Read and understand all instructions before operation. Always wear appropriate Personal Protective Equipment (PPE).

1. PPE Required: Safety glasses, hearing protection, sturdy gloves, long pants, and boots.
2. Clear Work Area: Remove stones, nails, wire, and other debris that could be thrown.
3. Fuel Safety: Refuel outdoors, with engine off and cool. Use only STIHL MotoMix® or equivalent 50:1 pre-mix. Wipe up spills.
4. Operation: Keep bystanders and pets at least 50 feet away. Hold unit firmly with both hands.
5. Hot Surfaces: Avoid contact with muffler and cylinder during and immediately after operation.

WARNING! Risk of serious injury or death from blade contact, thrown objects, fire, or carbon monoxide. Never operate indoors or in poorly ventilated areas.

Assembly & First Use

Unpack and inspect all parts. Assemble on a clean, stable surface.

1. Attach Shaft: Connect the drive shaft to the engine unit, aligning the arrows. Secure with the provided clamp.
2. Install Handle: Slide the loop handle onto the shaft at a comfortable position and tighten securely.
3. Install Cutting Attachment: For the C5-2 trimmer head, thread it onto the drive shaft (left-hand thread) and tighten firmly with the appropriate spanner.
4. Add Fuel: Fill the translucent tank with STIHL MotoMix® or a 50:1 gasoline/oil mixture (high-quality 2-stroke oil).
5. Initial Start: Place unit on clear ground. Set stop switch to "I". Press decompression valve. Pull starter cord smoothly until engine fires.

CAUTION! Ensure all fasteners are tight before operation. Do not force connections.

Specifications

• Engine Type: STIHL 2-stroke, single cylinder, air-cooled.
• Displacement: 27.2 cc (1.66 cu. in.).
• Power Output: 0.9 kW (1.2 bhp).
• Fuel/Oil Ratio: 50:1 (STIHL MotoMix® recommended).
• Fuel Tank Capacity: 0.53 liters (18 fl. oz.).
• Sound Pressure Level: Typically 96 dB(A).
• Vibration Level: Front/Rear handle: < 2.5 m/s².
• Weight (without cutting attachment): Approximately 5.1 kg (11.2 lbs).
• Drive System: Flexible drive shaft.
• Cutting Attachment Mount: Tapeless trimmer head (C5-2), also compatible with various STIHL blades.

Controls and Functions

Access all controls from the operator's position. Main controls located on the rear handle.

Rear Handle: Throttle trigger, Throttle trigger lockout, Stop switch (I/O).

Engine Housing: Decompression valve button, Starter grip, Choke lever (if equipped), Air filter cover.

Fuel System: Translucent fuel tank with cap, Fuel filter inside tank.

Starting Procedure: 1. Press decompression valve. 2. Set stop switch to "I". 3. Set choke if cold. 4. Pull starter cord smoothly until engine resists, then give a strong pull. 5. Move choke to run position as engine fires.

Fuel & Lubrication

Use only high-quality, unleaded gasoline with a minimum octane rating of 89 (RON). Mix with a high-performance 2-stroke engine oil at a 50:1 ratio. STIHL MotoMix® is pre-mixed and recommended.

1. Always refuel in a well-ventilated area, with the engine off.
2. Clean area around fuel cap before opening.
3. Use a funnel to avoid spills. Do not overfill.
4. Replace fuel cap securely and wipe any spilled fuel.
5. Gearbox Lubrication: Lubricate the gearbox at the cutting attachment with STIHL grease periodically.

Tip: Use fresh fuel. Do not use fuel older than 30 days. Empty tank for long-term storage.

Operation Guide

Designed for trimming grass and light brush. Can be fitted with blades for heavier brush.

1. Starting: Place unit on clear ground. Follow starting procedure. Allow engine to warm up at idle for 30 seconds.
2. Trimming Technique: Use a smooth, sweeping motion from side to side. Cut from right to left for best debris dispersal. Keep cutting head parallel to the ground.
3. Line Advance (C5-2): Tap the head firmly on the ground (with engine at high idle) to advance fresh line. Do not "bump" excessively.
4. Brush Cutting: Use appropriate metal blade. Use a swinging, scything motion. Let the blade do the work; do not force it.
5. Stopping: Release throttle and allow engine to idle briefly. Move stop switch to "O".

WARNING! Never operate the unit with one hand. Always maintain secure footing and balance.

Cutting Attachments

Compatible with a range of STIHL trimmer heads and blades.

• C5-2 Tapeless Trimmer Head: Standard. Uses .095" (2.4mm) diameter nylon line.
• Circular Grass Blades: 2-tooth or 4-tooth for dense grass and weeds.
• Brush Knives: 3-tooth or 80-tooth (chipper) for heavy brush and saplings.
• Metal Blade Guard: MUST be installed when using any metal cutting blade.

Installation: Ensure engine is off. Use the appropriate STIHL combination wrench to secure attachment. Right-hand thread for most blades, left-hand for trimmer heads.

Maintenance & Cleaning

Perform maintenance with engine off and spark plug wire disconnected.

1. Daily/Air Filter: Check and clean air filter. Replace if damaged or excessively dirty.
2. Spark Plug: Check and clean electrode gap (0.020" / 0.5mm). Replace annually or if worn.
3. Fuel Filter: Replace fuel filter in the tank every season or as needed.
4. Cooling Fins: Keep cylinder cooling fins clean of debris.
5. Exterior: Wipe unit clean with a dry cloth after each use. Remove grass and dirt from cutting attachment shield.
6. Gearbox: Lubricate with STIHL grease every 25 hours of operation.

CAUTION! Use only STIHL replacement parts. Improper parts can cause damage or injury.

Storage

Prepare unit for storage if it will not be used for more than 30 days.

1. Run the engine until it stops to use up all fuel in the carburetor.
2. Drain any remaining fuel from the tank into an approved container.
3. Remove spark plug, add a teaspoon of 2-stroke oil into the cylinder, pull starter cord slowly 2-3 times, reinstall plug.
4. Thoroughly clean the entire unit.
5. Store in a dry, locked place, out of reach of children, away from open flames or sparks.

Tip: Store the unit in its original box or cover it to keep dust out.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine will not start	No fuel, flooded, spark plug faulty, switch off	Check fuel; wait if flooded; check/replace spark plug; ensure stop switch is "I".
Engine starts then dies	Clogged fuel filter, dirty air filter, carburetor adjustment	Replace fuel filter; clean air filter; have carburetor serviced by a dealer.
Loss of power	Clogged air filter, dirty spark arrestor screen, old fuel	Clean air filter; clean spark arrestor screen; use fresh fuel.
Excessive vibration	Damaged cutting attachment, loose fasteners, bent drive shaft	Inspect and replace damaged blade/head; tighten all fasteners; inspect shaft.
Line does not advance	Empty spool, line tangled, worn bump mechanism	Refill spool with correct line; untangle or replace spool; inspect head.
Unusual engine noise	Loose components, internal engine wear	Stop engine immediately. Check for loose parts. Contact authorized STIHL dealer.

Service: For repairs beyond basic maintenance, contact an authorized STIHL servicing dealer. Use only genuine STIHL parts.

Support: For more information, visit www.stihlusa.com or contact your local STIHL dealer.