Stihl 028 WB Parts Manual

The Stihl 028 WB is a professional-grade chainsaw known for its reliability and power. This parts manual provides detailed diagrams, part numbers, and ordering information for the complete assembly, including the engine, cutting attachments, fuel system, ignition, and housing components. Below are key sections for identification, engine parts, fuel system, cutting attachments, assembly instructions, and ordering.

Identification & Serial Numbers

Locate the serial number plate on the rear housing. Key components: Cylinder, Piston, Crankshaft, Carburetor, Ignition Module, Chain Sprocket, Guide Bar, Oil Pump.

Component	Location/Description
Serial Number Plate	Stamped on rear housing near handle
Engine Type	028 WB (West German Model)
Cylinder Displacement	51.5 cc
Power Output	3.5 bhp
Fuel/Oil Mix Ratio	50:1 (Gasoline to 2-Stroke Oil)
Guide Bar Length Options	16", 18", 20"
Chain Pitch	.325"
Ignition System	Electronic, breakerless
Carburetor Type	Walbro or Tillotson diaphragm
Weight (Powerhead)	12.1 lbs (5.5 kg)

Engine Assembly Parts

Complete list of internal engine components with part numbers.

1. Cylinder Assembly: Includes cylinder, decompression valve, and gaskets.
2. Piston Assembly: Piston, rings, wrist pin, and circlips.
3. Crankshaft Assembly: Crankshaft, bearings, seals, and connecting rod.
4. Crankcase: Upper and lower halves with screws and dowels.
5. Flywheel & Fan: Flywheel, fan blades, and starter cup.

WARNING! Engine components are precision parts; handle with care to avoid damage. Use proper tools for disassembly.

Fuel System & Carburetor

Parts for fuel tank, lines, filter, and carburetor.

1. Fuel Tank: Tank assembly, cap, and vent.
2. Fuel Lines: Supply and return lines with clamps.
3. Fuel Filter: In-tank filter element.
4. Carburetor Kit: Diaphragms, gaskets, needle valve, and adjustment screws.
5. Air Filter: Foam filter element and cover.

CAUTION! Ensure fuel system is clean and free of debris before assembly. Use ethanol-resistant fuel lines.

Cutting Attachment Parts

• Guide Bar: Stihl Rollomatic E in 16", 18", 20" lengths.
• Chain Sprocket: Rim sprocket system (.325" pitch).
• Chain: Stihl 63PM3-XX (XX = drive link count).
• Bar Nuts & Bolts: Mounting hardware for bar and chain.
• Chain Tensioner: Screw, adjuster, and pin.
• Clutch Assembly: Drum, springs, shoes, and bearing.
• Oil Pump: Gear-driven pump, lines, and adjuster.

Ignition System

Components for spark generation and timing.

Ignition Module: Electronic coil with spark plug wire.

Spark Plug: Bosch WSR6F or equivalent.

Stop Switch: Wire harness and switch assembly.

Flywheel Key: Woodruff key for timing alignment.

Wiring Harness: Connects ignition to switch and ground.

Housing & Covers

External parts including handles, covers, and buffers.

1. Turn off saw and disconnect spark plug before servicing.
2. Match part numbers to exploded diagrams.
3. Assemble covers with correct fasteners and buffers.

Tip: Use anti-vibration buffers and rubber grommets to reduce wear.

Assembly Instructions

Step-by-step guide for critical assemblies.

1. Crankcase Assembly: Install crankshaft with bearings and seals; torque case halves.
2. Piston/Cylinder: Install piston with ring gaps aligned; slide cylinder over piston.
3. Ignition Timing: Align flywheel key; set air gap to 0.3mm.
4. Carburetor: Mount with gaskets; connect fuel lines and throttle linkage.
5. Clutch/Sprocket: Install clutch drum and sprocket; tighten nut.
6. Guide Bar/Chain: Mount bar; install chain with cutters facing forward; adjust tension.
7. Housing: Attach covers with screws and buffers; connect control linkages.

WARNING! Always use new gaskets and seals. Torque fasteners to specification.

Torque Specifications

Critical fastener torque values (Nm).

Fastener	Torque (Nm)	Notes
Cylinder Bolts	20 Nm	Crisscross pattern
Crankcase Screws	10 Nm	Loctite recommended
Flywheel Nut	40 Nm	Use holder tool
Clutch Nut	35 Nm	Right-hand thread
Spark Plug	25 Nm	Do not over-tighten
Guide Bar Nuts	12 Nm	Snug, then adjust tension

Exploded Diagrams

Refer to diagrams for part location and relationship.

Diagram 1: Engine Assembly (Cylinder, Piston, Crankshaft).

Diagram 2: Fuel System (Tank, Carburetor, Lines).

Diagram 3: Cutting Attachment (Clutch, Sprocket, Bar, Chain).

Diagram 4: Housing & Controls (Handles, Covers, Switches).

WARNING! Use diagrams for correct part orientation. Numbers correspond to part list.

Parts Ordering Guide

How to order genuine Stihl parts.

1. Identify part number from manual or diagram.
2. Contact authorized Stihl dealer with model and serial number.
3. Verify part compatibility for 028 WB version.
4. Order gasket and seal kits for overhaul.

Note: Non-genuine parts may void warranty and affect performance.

Troubleshooting & Service

Symptom	Possible Cause	Corrective Action
Engine won't start	Fuel, spark, compression	Check fuel mix, spark plug, compression (≥120 psi).
Engine runs poorly	Carburetor, air filter	Clean carburetor; replace filter; adjust H/L screws.
Chain doesn't turn	Clutch, sprocket, brake	Inspect clutch springs; replace worn sprocket; disengage brake.
No chain oil	Pump, lines, tank	Check oil lines for leaks; clean pump inlet; verify adjuster.
Excessive vibration	Mounts, balance	Replace anti-vibration buffers; balance clutch/flywheel.
Overheating	Airflow, fuel mix	Clean cooling fins; use correct 50:1 mix; check for lean condition.

Service Interval: Replace spark plug and air filter annually. Grease sprocket bearing regularly.

Support: Contact authorized Stihl service center or visit www.stihlusa.com.