The Stihl TS420 is a professional-grade cut-off saw designed for demanding construction, rescue, and demolition work. This parts manual provides detailed diagrams, part numbers, and ordering information for all components of the TS420 cut-off saw, including the engine, cutting system, fuel system, ignition, housing, and controls. Below are key sections for parts identification, ordering, assembly diagrams, specifications, and maintenance part replacements.
Key components groups: Engine Assembly (Cylinder, Piston, Crankshaft), Cutting System (Shaft, Blade Flange, Guard), Fuel System (Tank, Carburetor, Filters), Ignition (Flywheel, Coil, Spark Plug), Housing & Handles, and Fasteners.
| Component Group | Description |
|---|---|
| Engine Assembly | Cylinder, piston, crankshaft, bearings, seals, and gaskets |
| Cutting System | Drive shaft, spindle, blade flange, nut, and cutting guard |
| Fuel System | Fuel tank, carburetor, fuel lines, filter, and purge bulb |
| Ignition System | Flywheel, ignition coil, spark plug, stop switch, and wiring |
| Housing & Handles | Main housing, rear handle, front handle, anti-vibration elements |
| Fasteners & Decals | Screws, nuts, washers, and identification decals |
| Air Filter System | Air filter cover, filter element, and pre-cleaner |
| Exhaust System | Muffler, spark arrestor, and exhaust gasket |
| Starter Assembly | Starter pulley, rope, handle, and spring |
| Throttle Control | Throttle trigger, linkage, cable, and lockout lever |
Complete list of parts for the TS420 engine block and internal components.
WARNING! Engine disassembly requires specialized tools and training. Incorrect assembly can cause severe damage or injury.
Parts for the drive train and cutting attachment safety components.
CAUTION! Always use the correct guard for the cutting wheel. Never operate the saw without the guard properly installed.
Parts for starting and stopping the engine electronically.
Ignition Coil: Part number [e.g., 0000 000 0016] - Electronic ignition module.
Flywheel: Part number [e.g., 0000 000 0017] - Fan-cooled flywheel with magnets.
Spark Plug: Part number [e.g., BOSCH WSR6F or equivalent] - Recommended spark plug.
Stop Switch: Part number [e.g., 0000 000 0018] - Engine stop switch/button assembly.
Wiring Harness: Part number [e.g., 0000 000 0019] - Main wiring loom.
Starter Assembly: Part number [e.g., 0000 000 0020] - Complete starter assembly (rope, pulley, spring).
External parts for housing, vibration damping, and operator controls.
Tip: When replacing handles, ensure all anti-vibration elements are correctly seated to maintain user comfort and safety.
Supports all screws, nuts, washers, pins, and identification labels.
WARNING! Always use genuine Stihl fasteners with the correct torque specifications. Substandard fasteners can fail during operation.
How to order genuine Stihl TS420 parts.
Ordering Process: Use the 10-digit part number from this manual. Contact an authorized Stihl dealer or use the online parts portal at [stihlusa.com/parts].
CAUTION! Use only genuine Stihl parts to maintain performance, safety, and warranty coverage.
Refer to the numbered diagrams in the full PDF manual for visual part location and assembly order.
Parts critical to safe operation must be replaced immediately if damaged.
| Safety Part | Function | Replacement Interval |
|---|---|---|
| Cutting Guard | Protects operator from debris and wheel rupture | Inspect before each use; replace if cracked or damaged |
| Anti-Vibration Elements | Reduces user fatigue and improves control | Replace if hardened, cracked, or worn |
| Throttle Lockout Lever | Prevents accidental throttle activation | Must function smoothly; replace if broken or sticky |
| Spark Arrestor Screen | Prevents emission of sparks | Clean regularly; replace if clogged or damaged |
| Fuel Lines | Prevents fuel leaks and fire hazard | Replace annually or if cracked/leaking |
| Symptom | Possible Failed Part | Corrective Action |
|---|---|---|
| Engine won't start | Spark plug, ignition coil, fuel filter | Check spark; replace plug or coil; install new fuel filter. |
| Loss of power | Air filter, fuel filter, carburetor diaphragm | Clean/replace air filter; replace fuel filter; rebuild carburetor. |
| Excessive vibration | Worn anti-vibration buffers, bent drive shaft | Replace all anti-vibration elements; inspect and replace shaft if bent. |
| Oil leak from crankcase | Crankshaft seals, base gasket | Replace crankcase seals and cylinder base gasket. |
| Cutting wheel wobbles | Bent spindle, worn blade flange | Replace spindle assembly and blade flange. |
Dealer Service: For complex repairs, contact an authorized Stihl servicing dealer.
Support: 1-800-467-8445; www.stihlusa.com