STIHL TS 500i Repair Manual

The STIHL TS 500i is a professional-grade cut-off saw featuring STIHL's innovative fuel injection system (M-Tronic), offering consistent power, easy starting, and reduced emissions. This manual provides comprehensive repair, maintenance, and troubleshooting information for qualified technicians. Below are key sections covering safety, specifications, engine systems, fuel system, electrical system, cutting equipment, assembly/disassembly, and troubleshooting procedures.

1. Safety Information & Warnings 2. Technical Specifications 3. Engine Overview & M-Tronic System 4. Fuel System Repair 5. Ignition & Electrical System 6. Cutting Attachment & Guard 7. Disassembly & Assembly Procedures 8. Carburetor Adjustment (M-Tronic) 9. Maintenance Schedule 10. Parts Diagrams & Ordering 11. Troubleshooting Guide

Safety Information & Warnings

Before performing any repair, read and understand all safety instructions. Use proper personal protective equipment (PPE).

Hazard	Precaution
Fuel Fire/Explosion	Work in well-ventilated area away from sparks or flames. Drain fuel tank before disassembly.
Hot Surfaces	Allow engine and exhaust to cool completely before handling.
Sharp Edges	Wear cut-resistant gloves when handling cutting disc, guide bar, or chain.
Spring Force	Use appropriate tools when handling starter spring or other tensioned components.
Electrical Shock	Disconnect spark plug boot before working on ignition or electrical components.

WARNING! This manual is for trained technicians. Incorrect repair can cause serious injury or damage. Use only genuine STIHL parts.

Technical Specifications

Model: STIHL TS 500i
Engine Type: 2-stroke, single cylinder, air-cooled
Displacement: 81.6 cm³
Power Output: 4.1 kW (5.5 hp)
Fuel System: STIHL M-Tronic electronic fuel injection
Ignition System: Electronic, capacitor discharge (CDI)
Starting System: Rewind starter
Fuel/Oil Mix: 50:1 with STIHL HP Ultra or equivalent ISO-L-EGD certified oil
Cutting Attachment: Accepts various cut-off wheels and diamond blades (max. 14" / 355 mm)
Weight (powerhead): Approx. 9.9 kg (21.8 lbs)

Engine Overview & M-Tronic System

The M-Tronic system automatically adjusts fuel mixture based on engine load, altitude, and temperature using sensors and an electronic control unit (ECU).

ECU: Mounted in the handle housing. Controls fuel solenoid valve.
Sensors: Monitor crankshaft speed, cylinder temperature, and intake air pressure.
Fuel Solenoid Valve: Regulates fuel flow from the pump to the injection nozzle.
Operation: No manual carburetor adjustment screws. System self-calibrates on startup and during operation.

CAUTION! Do not attempt to modify or bypass the M-Tronic system. Use STIHL diagnostic tool for troubleshooting.

Fuel System Repair

Components: Fuel tank, filter, lines, primer bulb, fuel pump, M-Tronic solenoid, injection nozzle.

Fuel Line Replacement: Drain tank. Remove tank cover. Disconnect old lines and connect new ones (impulse, supply, return).
Fuel Filter: Replace periodically or if clogged. Access through filler neck.
Fuel Pump: Test pressure (spec: 2.5 - 3.5 bar). Replace if diaphragm is damaged or pressure is low.
Injection Nozzle: Located in intake manifold. Check for clogging; clean with appropriate solvent if necessary.

Tip: Always use clean fuel and replace all fuel lines as a set to prevent air leaks.

Ignition & Electrical System

Components: Spark plug, ignition module (CDI), stop switch, wiring harness, starter.

Spark Plug: NGK BPMR 7A (gap 0.5 mm). Check and replace if fouled or electrode worn.

Ignition Module Test: Use STIHL multimeter or diagnostic tool. Check primary and secondary coil resistance against specifications.

Stop Switch: Test for continuity between black wire and ground when switch is pressed.

Starter Repair: Common issues: broken rope, worn pawls, failed spring. Use proper winding procedure when reassembling.

Cutting Attachment & Guard

Includes spindle, flange, nut, guard, and handle. Compatible with abrasive cut-off wheels and diamond blades.

Disc Installation: Ensure guard is properly mounted. Place disc on spindle with correct orientation (arrow on disc matching rotation). Secure with flange and nut (tighten clockwise).
Guard Adjustment: Loosen knob, position guard for optimal protection, retighten.
Bearing Check: Check spindle bearing for play or roughness. Replace if necessary.

WARNING! Always use the correct guard for the cutting disc. Never operate without the guard in place.

Disassembly & Assembly Procedures

General sequence for engine disassembly.

Remove cutting attachment, guard, and handle.
Remove fuel tank cover and air filter cover.
Disconnect all fuel lines, throttle linkage, and wiring connectors.
Remove cylinder cover and muffler.
Remove cylinder base nuts. Separate crankcase halves using a case splitter tool.
Remove crankshaft, piston, connecting rod, and bearings.
Assembly: Reverse order. Use new gaskets and seals. Torque fasteners to specification.

CAUTION! Mark components for reassembly. Use a service manual with detailed torque specs.

Carburetor Adjustment (M-Tronic)

The M-Tronic system requires no manual adjustment under normal conditions. However, a reset procedure can be performed if running issues occur.

Reset Procedure: Start the engine and let it run at idle for at least 1 minute. Then run at full throttle (no load) for 1 minute. The ECU will relearn optimal settings.
Manual Override (Service Mode): Requires STIHL diagnostic tool (HDS) to read error codes or force recalibration.

Note: If problems persist after reset, check for air leaks, fuel delivery issues, or faulty sensors.

Maintenance Schedule

Interval (Operating Hours)	Task
Daily or Before Use	Check fuel level, inspect cutting disc and guard for damage, check all fasteners for tightness.
20 Hours	Clean air filter, check spark plug.
50 Hours	Replace fuel filter, clean spark arrestor screen in muffler.
100 Hours	Check fuel lines, inspect piston through exhaust port, clean cooling fins.
As Needed	Replace cutting disc, sharpen/replace diamond blade segments.

Parts Diagrams & Ordering

Refer to official STIHL parts catalog for exploded views and part numbers. Key assemblies: Engine Crankcase (1110), Fuel System (1125), Ignition System (1135), Cutting Attachment (1140).

Ordering: Use genuine STIHL part numbers. Contact an authorized STIHL dealer or visit www.stihlusa.com.

Troubleshooting Guide

Symptom	Possible Cause	Corrective Action
Engine will not start	No spark, no fuel, flooded	Check spark plug, fuel supply, and primer bulb. Perform M-Tronic reset.
Engine starts then dies	Clogged fuel filter, air leak, faulty M-Tronic	Replace fuel filter. Check intake manifold and crank seals. Run diagnostic.
Loss of power	Clogged air filter, exhaust port carbon, faulty ignition	Clean/replace air filter. Decarbonize exhaust port. Check ignition timing.
Excessive vibration	Unbalanced cutting disc, bent spindle, engine mount loose	Replace disc. Check spindle runout. Tighten all engine mounts.
M-Tronic error (blinking warning light)	Sensor fault, wiring issue, ECU failure	Connect STIHL diagnostic tool to read fault code. Check sensor connections.

Service Support: For complex issues, contact STIHL Technical Service or an authorized STIHL servicing dealer.