Stihl TS400 Repair Manual

The Stihl TS400 is a professional-grade cut-off saw designed for demanding construction, demolition, and rescue applications. This repair manual provides comprehensive instructions for troubleshooting, maintenance, disassembly, and reassembly of the TS400 model. It covers the engine, fuel system, ignition, cutting system, and safety components to ensure proper repair and safe operation.

Safety Precautions & Warnings

Before attempting any repair, read all safety instructions. Always wear appropriate PPE (safety glasses, gloves, hearing protection). Ensure the engine is completely cool and the spark plug boot is disconnected to prevent accidental starting. Work in a clean, well-ventilated area away from ignition sources.

Hazard	Precaution
Fuel Fire/Explosion	Drain fuel tank before service. No smoking.
Accidental Start-up	Disconnect spark plug wire and secure it away from plug.
Sharp Components	Handle cutting disc, clutch springs, and gears with care.
Hot Surfaces	Allow muffler and cylinder to cool completely.
Toxic Fumes	Service in ventilated area; avoid inhaling fuel/oil vapors.

Technical Specifications

• Model: Stihl TS 400 Cut-Off Saw
• Engine Type: 2-stroke, single cylinder, air-cooled
• Displacement: 64.1 cm³ (3.91 cu. in.)
• Power Output: 3.0 kW (4.1 HP)
• Fuel/Oil Mix: 50:1 (Stihl HP Ultra or equivalent)
• Idle Speed: 2,800 RPM
• Max. RPM (no load): 12,500 RPM
• Cutting Disc Diameter: 300 mm (12") or 350 mm (14")
• Weight (powerhead): Approx. 8.6 kg (19.0 lbs)
• Ignition System: Electronic, CDI

Tools & Equipment Required

Standard mechanic's tool set plus Stihl specialty tools.

1. Stihl ring nut wrench (for clutch removal)
2. Piston stop tool
3. Flywheel puller
4. Carburetor adjustment tool (splined)
5. Torque wrench (capable of 5-50 Nm)
6. Compression tester
7. Feeler gauges (for spark plug gap)
8. Clean shop rags and parts cleaning solvent

WARNING! Use only Stihl-approved tools for specific fasteners to avoid damage.

Engine System Repair

Cylinder, piston, crankshaft, and bearings service.

1. Compression Test: Remove spark plug, screw in tester, pull starter cord briskly. Reading below 110 psi indicates wear.
2. Cylinder Inspection: Remove muffler, inspect cylinder walls for scoring. Light honing possible; deep scores require replacement.
3. Piston & Rings: Remove cylinder base nuts. Check ring end gap; replace if over specification. Ensure ring pins are intact.
4. Crankshaft Seals: Check for leaks (air/fuel). Replace if hardened, cracked, or leaking (causes lean run condition).

CAUTION! Label all parts during disassembly. Replace gaskets and seals during reassembly.

Fuel System Service

Fuel tank, lines, filter, and pump.

Fuel Line Replacement: Drain tank. Remove old lines from tank grommet and carburetor. Cut new lines to length, ensure secure fit. Prime bulb should fill with fuel.

Fuel Filter: Replace annually or if clogged. Attach to end of fuel line inside tank.

Impulse Line: Inspect the small line from crankcase to fuel pump. Cracks cause fuel delivery failure.

Component	Service Interval	Action
Fuel Filter	Every 3 months or 50 hrs	Replace
Fuel Lines	Annually or if cracked	Inspect/Replace
Tank Vent	If fuel flow is restricted	Clean/Replace

Ignition System Troubleshooting

Spark plug, ignition module, flywheel, and stop switch.

1. Spark Test: Remove plug, reconnect boot, ground plug base to cylinder. Pull starter; look for strong blue spark.
2. No Spark: Check boot connection, stop switch wire (disconnect to test), and flywheel key (sheared key alters timing).
3. Weak/Intermittent Spark: Test ignition coil air gap (0.2-0.4 mm). Replace coil if faulty.
4. Flywheel: Check magnets for damage. Use puller for removal; do not hammer.

Spark Plug: NGK BPMR7A. Gap: 0.5 mm (0.020"). Replace yearly.

Cutting Attachment & Drive

Clutch, drive shaft, gear head, and spindle.

Clutch Service: Remove using ring nut wrench. Inspect shoes for wear, springs for fatigue. Clean drum interior.

Gear Head Lubrication: Fill with Stihl Gear Oil (approx. 100 ml). Check for leaks at seals.

Spindle Bearing: Check for play or roughness. Replace if damaged.

Cutting Disc Mounting: Always use correct flange washers and tighten spindle nut to specified torque (approx. 50 Nm). Disc must rotate freely without contacting guard.

Carburetor Adjustment

Standard settings for Zama C1Q-S series carburetor.

1. Initial Settings: Turn H (high) and L (low) screws gently clockwise to seat, then back out: H = 1 turn, L = 1 turn.
2. Final Adjustment (Warm Engine): Set idle speed screw so chain just doesn't turn. Adjust L for fastest idle, then turn out 1/4 turn. Adjust H for max RPM, then rich slightly (turn counter-clockwise) for 4-stroke burble. Re-check idle.
3. Acceleration Test: Throttle from idle to full should be immediate without hesitation.

WARNING! Incorrect H screw setting can cause engine seizure. Use tachometer for accuracy.

Routine Maintenance Schedule

Keep a log of all service.

Interval	Task
Daily	Check cutting disc for damage, tightness. Clean air intake.
Every 10 hrs	Clean air filter (more often in dusty conditions).
Every 25 hrs	Check spark plug, clean/replace. Inspect fuel filter.
Every 50 hrs	Clean cooling fins. Check clutch and gear head.
Every 100 hrs	Replace fuel lines. Decarbonize exhaust ports.
Annually	Full inspection: crankshaft seals, bearings, compression test.

Parts Diagrams & Numbers

Key replacement part numbers (verify with your serial number).

• Cylinder Kit: 1128 020 1205
• Piston Kit: 1128 030 2001
• Carburetor Kit: 1128 007 1060
• Ignition Module: 1128 400 1301
• Clutch Assembly: 1128 160 2001
• Fuel Pump Diaphragm Kit: 1128 007 1055
• Air Filter: 1128 120 1600
• Spark Plug: NGK BPMR7A (Stihl # 0000 400 1300)

Refer to official Stihl IPL (Illustrated Parts List) for your specific serial number range.

Common Faults & Solutions

Symptom	Possible Cause	Corrective Action
Engine won't start	No spark, flooded, fuel issue	Check spark, plug condition. Dry plug, use choke correctly. Check fuel flow.
Engine starts then dies	Clogged fuel filter, tank vent, carburetor	Replace filter. Clean tank vent. Service carburetor (diaphragms, gaskets).
Loss of power under load	Dirty air filter, exhaust screen, incorrect carb adjustment	Clean/replace air filter. Decarbonize spark arrestor screen. Adjust carburetor.
Excessive vibration	Bent cutting disc, unbalanced disc, loose fasteners	Inspect disc for damage. Ensure proper mounting. Tighten all engine and attachment bolts.
Clutch slipping/not engaging	Worn clutch shoes, oily clutch drum, weak springs	Replace clutch assembly. Clean drum with degreaser.
Oil leak from gear head	Worn/damaged seals, overfilled, cracked housing	Replace output shaft seals. Fill to correct level. Inspect housing.

Reset: After major repair, allow engine to idle for 3-5 minutes before applying load.

Service: For genuine parts and technical support, contact an authorized Stihl dealer or visit www.stihlusa.com.