STIHL FS 56 RC Repair Manual

The STIHL FS 56 RC is a lightweight, professional-grade gasoline-powered string trimmer/brushcutter featuring a loop handle, bicycle handle, or D-handle options, a 1.0 HP engine with STIHL anti-vibration system, a translucent fuel tank, a semi-automatic choke, a decompression valve, a translucent fuel tank, a QuickStop® inertia chain brake, and a TapTronic® electronic ignition system. This manual provides comprehensive repair, maintenance, and troubleshooting guidance for qualified technicians. Below are key sections for safety, specifications, disassembly, engine service, fuel system, ignition, troubleshooting, and reassembly.

Safety Precautions & Warnings

Before any repair, disconnect the spark plug boot to prevent accidental starting. Work in a clean, well-ventilated area. Use STIHL-approved tools and replacement parts. Wear appropriate personal protective equipment (PPE).

Hazard	Precaution
Fuel Fire/Explosion	Drain fuel tank before service. No smoking or open flames.
Hot Surfaces	Allow engine to cool completely before disassembly.
Sharp Cutting Tools	Handle cutting attachments with heavy gloves. Secure trimmer head.
Spring-Loaded Components	Use caution when removing starter assembly and recoil spring.
Chemical Exposure	Use gloves when handling fuel, oil, or cleaning solvents.

WARNING! Improper repair can cause serious injury or death. This manual is for trained technicians only.

Specifications & Identification

• Model: FS 56 RC
• Engine Type: STIHL single-cylinder, 2-stroke, air-cooled
• Displacement: 27.2 cc (1.66 cu. in.)
• Power Output: 0.75 kW (1.0 hp) at 9000 rpm
• Idle Speed: 2800 rpm
• Fuel/Oil Mix: 50:1 (STIHL HP Ultra or equivalent ISO-L-EGD certified oil)
• Fuel Tank Capacity: 0.47 L (0.12 US gal)
• Ignition System: STIHL TapTronic® electronic, capacitor discharge
• Spark Plug: Bosch WSR 6 F or equivalent, gap 0.5 mm (0.020 in.)
• Carburetor: Zama C1Q-S series (adjustable H, L, LA screws)
• Drive Shaft: Flexible, helical spline
• Gearhead: Bevel gear, grease lubricated
• Weight (powerhead): Approx. 5.2 kg (11.5 lbs)

Identification: Serial number located on crankcase. Use for ordering correct parts.

Tools & Special Equipment

Standard mechanic's tools plus STIHL special tools recommended for efficient service.

1. STIHL Flywheel Holder (1106 890 4500)
2. STIHL Piston Stop (1106 890 4000)
3. STIHL Clutch Removal Tool (1106 890 4700)
4. STIHL Carburetor Adjustment Tool (5910 890 4500)
5. Torque Wrench (3-20 Nm range)
6. Compression Gauge
7. Vacuum/Pressure Tester (for crankcase seals)
8. Feeler Gauges
9. Spark Tester

Disassembly Sequence

Systematic teardown to access internal components.

1. Remove cutting attachment and guard.
2. Remove fuel tank cap and drain fuel into approved container.
3. Remove air filter cover and filter element.
4. Remove starter assembly (note spring orientation).
5. Remove muffler and heat shield.
6. Remove carburetor and intake manifold.
7. Remove ignition module (coil) after marking position.
8. Use flywheel holder and remove flywheel nut. Pull flywheel with appropriate puller.
9. Remove clutch assembly using clutch removal tool.
10. Separate crankcase halves after removing all screws (note locations).

Tip: Take photos or make sketches during disassembly for reassembly reference.

Engine Overhaul

Inspection and service of crankshaft, piston, cylinder, and bearings.

Cylinder & Piston: Inspress for scoring, carbon buildup, and wear. Measure piston clearance. Honing may be done for light scoring; severe damage requires replacement. Check ring end gap and ring free movement in groove.

Crankshaft & Bearings: Check for play at connecting rod big end. Inspect main bearings for smooth rotation and no radial play. Replace crankshaft seals whenever engine is split.

Crankcase Seals: Test with vacuum/pressure tester. Leaking seals cause lean run condition and engine damage.

Compression: Should be a minimum of 120 psi (8.3 bar) for proper operation.

Fuel System Service

Fuel tank, lines, filter, and carburetor service.

1. Fuel Tank: Inspect for cracks. Clean interior if contaminated.
2. Fuel Lines: Replace if hardened, cracked, or discolored. Use STIHL OEM lines.
3. Fuel Filter: Replace regularly. Located inside tank.
4. Carburetor Diaphragms & Gaskets: Replace as a kit during overhaul. Check metering lever height (should be flush with carburetor body floor).
5. Impulse Line: Check for cracks; connects carburetor to crankcase.

CAUTION! Use only ethanol-resistant fuel lines and diaphragms to prevent degradation.

Ignition System (TapTronic®)

The TapTronic® system advances timing based on engine speed. Testing procedure:

1. Check spark plug boot and wire for damage.
2. Use a spark tester set to 6mm gap. Crank engine; strong blue spark should be visible.
3. Check air gap between ignition module and flywheel magnets. Should be 0.3 mm (0.012 in.). Adjust by loosening module screws and using a feeler gauge.
4. If no spark, test stop switch circuit for continuity (should be open circuit when switch is off/run, closed to ground when stop is pressed).
5. Replace ignition module if all other checks pass and no spark is present.

Carburetor Adjustment

Initial settings after rebuild or cleaning. Engine must be at operating temperature.

• LA (Low Speed Air): 1 turn open from lightly seated.
• L (Low Speed Fuel): 1 turn open from lightly seated.
• H (High Speed Fuel): 1 turn open from lightly seated.

Fine-Tuning Procedure:

1. Start engine and let warm up for several minutes.
2. Adjust L screw for smoothest idle and quick acceleration without hesitation.
3. Adjust H screw for maximum RPM (do not exceed 13,000 rpm no-load), then richen slightly (turn counterclockwise) by about 1/8 turn for proper 4-stroking under load.
4. Re-check idle and acceleration. Final idle speed should be 2800 rpm.

Use a tachometer for accurate adjustment.

Gearhead & Drive Shaft

Service of the lower transmission and drive shaft.

1. Remove gearhead cover.
2. Inspect bevel gears for wear or chipping. Replace as a set.
3. Clean old grease and repack with STIHL gear grease.
4. Check drive shaft for kinks or damage. Lubricate with STIHL drive shaft grease during reassembly.
5. Inspect shaft bearings in the shaft tube for smooth rotation.

Note: Over-tightening the trimmer head can damage the gearhead threads.

Cutting Attachment Service

FS 56 RC commonly uses a TapTronic® compatible trimmer head (AutoCut C 2-2) or a circular brush knife.

Trimmer Head (AutoCut):

1. Remove spool by depressing locking tabs and pulling out.
2. Clean debris from inside head.
3. Wind new monofilament line onto spool following direction arrows. Lead ends through eyelets.
4. Reinstall spool, ensuring it clicks into place.

Brush Knife: Inspect for sharpness, cracks, or imbalance. Sharpen or replace as needed. Ensure proper guard is installed.

Troubleshooting Guide

Symptom	Possible Cause	Corrective Action
Engine will not start	No spark, no fuel, flooded	Check spark, fuel delivery, carburetor. Choke off, throttle locked, pull with decomp valve.
Engine starts but dies	Clogged fuel filter, bad diaphragm, air leak	Replace fuel filter, carb kit, pressure test crankcase.
Loss of power	Clogged air filter, exhaust screen, improper H adjustment	Clean/replace filter, clean spark arrestor screen, adjust H screw.
Excessive vibration	Bent drive shaft, unbalanced cutting tool, loose engine mounts	Inspect shaft, balance/replace tool, tighten mounts.
Transmission overheats	Low grease, damaged gears, over-tightened head	Repack grease, inspect/replace gears, hand-tighten head only.
High fuel consumption	H screw too rich, leaking fuel lines, float level high	Adjust H screw, replace lines, check metering lever height.

Reassembly & Torque Specifications

Reverse of disassembly, using new gaskets and seals. Critical torque values:

• Crankcase screws: 8 Nm (71 in. lbs)
• Cylinder nuts: 10 Nm (88 in. lbs)
• Flywheel nut: 35 Nm (26 ft. lbs) – use thread locker
• Clutch: 35 Nm (26 ft. lbs) – RH thread
• Spark Plug: 20 Nm (15 ft. lbs)
• Muffler screws: 8 Nm (71 in. lbs)

Final Steps: Fill gearhead with grease. Lubricate drive shaft. Add fresh 50:1 fuel mix. Start engine and check for leaks. Perform carburetor adjustment. Test all functions under load.

Service Support: For technical assistance or genuine STIHL parts, contact an authorized STIHL servicing dealer or visit www.stihlusa.com.