STIHL Saw TS400 Service Manual

The STIHL TS400 is a professional-grade cut-off saw designed for demanding construction and demolition work. This manual provides essential information for the safe maintenance, troubleshooting, and repair of the TS400 saw, including its engine, fuel system, cutting assembly, and safety features. Below are key sections covering safety, specifications, maintenance procedures, troubleshooting, and parts information.

1. Features at a Glance 2. Safety Information 3. Specifications 4. Maintenance Schedule 5. Engine Service 6. Fuel System 7. Cutting Assembly 8. Ignition System 9. Troubleshooting 10. Parts Diagram 11. Warranty & Support

Features at a Glance

Key components: Two-stroke engine, anti-vibration system, quick-release cutting head guard, electronic ignition (CDI), STIHL ElastoStart starter, and a centrifugal clutch.

Feature	Description
Engine Type	STIHL single-cylinder two-stroke engine
Displacement	64.1 cm³ (3.91 cu. in.)
Power Output	3.0 kW (4.0 hp)
Fuel Tank Capacity	0.95 L (32.1 fl. oz.)
Cutting Wheel Diameter	300 mm (12 in.) or 350 mm (14 in.)
Weight (without cutting wheel)	Approx. 9.8 kg (21.6 lbs)
Anti-Vibration System	Integrated dampers in handle and engine mounts
Starter System	STIHL ElastoStart with decompression valve
Ignition System	Electronic CDI ignition
Clutch	Centrifugal clutch, automatic engagement

Safety Information

Always wear appropriate Personal Protective Equipment (PPE) including safety glasses, hearing protection, gloves, and sturdy footwear.

Before servicing: Stop the engine, allow it to cool, and disconnect the spark plug boot.
Fuel Safety: Refuel in a well-ventilated area, away from ignition sources. Use only STIHL-approved fuel mix.
Cutting Safety: Ensure the cutting wheel guard is properly installed and secure before operation.
Hot Surfaces: Be aware of hot engine and exhaust components during and after use.

WARNING! Failure to follow safety instructions can result in serious injury or death. This saw is for professional use only.

Specifications

Model: STIHL TS 400.
Engine: Air-cooled, single-cylinder two-stroke.
Idle Speed: 2,800 rpm.
Maximum Power Speed: 9,000 rpm.
Fuel/Oil Mix Ratio: 50:1 (STIHL HP Ultra or equivalent).
Spark Plug: Bosch WSR 6 F or equivalent, gap 0.5 mm (0.020 in.).
Carburetor: Zama C1Q-S189 or equivalent.
Vibration Level (Front/Rear Handle): < 2.5 m/s².
Sound Pressure Level: 106 dB(A).
Sound Power Level: 119 dB(A).

Maintenance Schedule

Regular maintenance is critical for performance and safety. Access components as needed.

Daily/Before Use: Check for loose fasteners, inspect cutting wheel and guard, check fuel system for leaks.

Every 50 Hours: Clean air filter, check spark plug, inspect fuel filter.

Every 100 Hours: Clean spark arrestor screen (muffler), check clutch and drum for wear.

Annually or Every 300 Hours: Clean carburetor, check all rubber mounts and anti-vibration elements, replace fuel lines if cracked.

Engine Service

Cylinder and Piston: Inspect for scoring. Use a feeler gauge to check piston ring end gap (service limit: 0.8 mm). Crankshaft Seals: Check for leaks which can cause lean running. Decompression Valve: Ensure it opens and closes freely; clean carbon deposits.

Remove the muffler and cylinder cover for inspection.
Measure cylinder bore wear; maximum out-of-round: 0.05 mm.
Check connecting rod small-end bearing for play.

Tip: Always use a torque wrench when reassembling cylinder head bolts (20 Nm / 15 ft-lb).

Fuel System

Includes tank, cap, lines, filter, and carburetor.

Fuel Filter: Replace if clogged. Access through tank filler neck with hook tool.
Fuel Lines: Inspect for cracks or brittleness. Replace in pairs (supply and return).
Carburetor Adjustment: Use H and L screws for high and low speed mixture. Initial settings: H - 1 turn open, L - 1 turn open.
Carburetor Diaphragms: Check for stiffness or tears; replace kit if necessary.

WARNING! Use only STIHL-approved 50:1 pre-mix fuel. Improper fuel can cause engine damage.

Cutting Assembly

Includes spindle, centrifugal clutch, cutting wheel guard, and wheel.

Clutch Inspection: Remove cover. Check shoes for wear and springs for integrity.
Spindle Bearings: Check for smooth rotation and no axial play.
Cutting Wheel Mounting: Always use the correct flange and nut. Tighten nut securely against rotation direction.
Guard: The quick-release mechanism must lock positively. Inspect for cracks.

CAUTION! Never operate the saw without the cutting wheel guard properly installed and locked.

Ignition System

Electronic CDI unit, spark plug, stop switch, and wiring.

Spark Plug: Clean electrodes, adjust gap to 0.5 mm. CDI Unit: Test with multimeter per specifications (primary resistance ~0.5 Ω). Stop Switch: Ensure it grounds the ignition when pressed. Flywheel: Check key for shearing; ensure tight fit on crankshaft taper.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine will not start	No spark, flooded, fuel issue	Check spark plug, boot, and stop switch. Dry plug if flooded. Check fuel lines and filter.
Engine starts but dies	Clogged fuel filter, carburetor issue	Replace fuel filter. Clean or rebuild carburetor. Check tank vent.
Loss of power	Dirty air filter, clogged spark arrestor, exhaust port carbon	Clean air filter and spark arrestor screen. Decarbonize exhaust port and muffler.
Excessive vibration	Unbalanced cutting wheel, worn anti-vibration mounts	Replace cutting wheel. Inspect and replace rubber engine and handle mounts.
Clutch not engaging	Worn clutch shoes, weak springs	Inspect clutch assembly; replace shoes and springs as a set.
Oil leaking from crankcase	Failed crankshaft seals	Pressure test crankcase. Replace both main seals.

Reset: For electronic issues, disconnect spark plug boot for 1 minute to reset CDI module.

Parts Diagram

Refer to official STIHL parts catalog (Diagram Number: 9910 850 0650) for exploded views and part numbers for the TS400. Key assembly groups: 1100 (Cylinder/Piston), 1200 (Crankshaft), 1300 (Fuel System), 1400 (Ignition), 1500 (Clutch/Cutting Assembly), 1600 (Handle/Anti-Vibration).

Common Replacement Parts: Air Filter (Part# 0000 350 4005), Spark Plug (Part# 0000 400 1305), Fuel Filter (Part# 0000 350 3500), Clutch Shoe Set (Part# 0000 400 0805).

Warranty & Support

STIHL TS400 Professional Cut-Off Saws are covered by a 12-month commercial warranty from date of purchase. Warranty covers defects in materials and workmanship under normal use. It does not cover damage from misuse, lack of maintenance, or use of non-STIHL parts or fuel. For technical support, genuine parts, and service, contact an authorized STIHL servicing dealer. For dealer locator and manuals, visit www.stihlusa.com or contact STIHL Incorporated at 1-800-467-8445.