Stihl 026 Service Manual

The Stihl 026 is a professional-grade chainsaw known for its reliability, power-to-weight ratio, and durability. This service manual provides detailed instructions for maintenance, troubleshooting, and repair of the Stihl 026 chainsaw, including its engine, fuel system, ignition, chain brake, clutch, and cutting equipment. Below are key sections covering safety, specifications, maintenance procedures, disassembly/assembly, troubleshooting, and parts information.

Features at a Glance

Key components: Engine, Fuel System, Ignition, Chain Brake, Clutch, Guide Bar, and Chain.

Feature	Description
Engine Type	2-stroke, single-cylinder, air-cooled
Displacement	49.4 cc (3.01 cu in)
Power Output	Approx. 2.6 kW (3.5 hp)
Fuel System	Diaphragm carburetor (Walbro or Zama)
Ignition System	Electronic, breakerless
Chain Brake	Inertia-activated, manual release
Clutch	Centrifugal, drum-type
Guide Bar Length	Typically 16" to 20" (40-50 cm)
Chain Pitch	.325" or 3/8"
Weight (powerhead)	Approx. 5.2 kg (11.5 lbs)

Safety Information

Always follow safety precautions to prevent injury.

1. Wear protective gear: Safety glasses, gloves, hearing protection, chainsaw chaps, and sturdy boots.
2. Work in a well-ventilated area away from sparks or open flames.
3. Disconnect spark plug before performing any maintenance.
4. Use only Stihl-approved parts and fuels (gasoline-oil mix).

WARNING! Gasoline is flammable; handle with care. Ensure saw is cool before servicing.

Specifications

• Engine: 2-stroke, 49.4 cc, bore x stroke: 40 mm x 39.2 mm.
• Fuel: Gasoline-oil mix (50:1 with Stihl HP Ultra or equivalent).
• Ignition: Electronic, air gap: 0.3 mm (0.012 in).
• Carburetor: Walbro HDA or Zama C1Q series.
• Chain Oil: Stihl chain oil or equivalent SAE 30.
• Spark Plug: Bosch WSR6F or NGK BPMR7A, gap: 0.5 mm (0.020 in).
• Idle Speed: 2,800 - 3,200 rpm.
• Max Power Speed: Approx. 13,000 rpm.

Maintenance Schedule

Regular maintenance ensures optimal performance and longevity.

Daily/Before Use: Check chain tension, sharpness, and lubrication; inspect for loose fasteners; clean air filter.

Weekly/10 Hours: Clean spark arrestor screen; check fuel filter; inspect clutch and sprocket.

Monthly/50 Hours: Replace spark plug; clean carburetor; check ignition module; inspect fuel lines.

Annually/100 Hours: Replace fuel filter; check cylinder and piston; inspect chain brake components.

Fuel System Service

Includes fuel tank, lines, filter, and carburetor.

1. Drain fuel tank before disassembly.
2. Replace fuel filter: Remove tank cap, extract filter with wire hook.
3. Inspect fuel lines for cracks; replace if necessary.
4. Carburetor service: Clean jets, check diaphragm and gaskets.

Tip: Use compressed air to clean carburetor passages; avoid damaging diaphragms.

Ignition System

Electronic ignition module and spark plug.

1. Check spark: Remove plug, ground electrode to cylinder, pull starter; look for blue spark.
2. Ignition module: Test resistance (primary: 0.5-2.0 Ω; secondary: 8-15 kΩ).
3. Air gap: Set between flywheel and module legs to 0.3 mm (0.012 in).
4. Replace spark plug annually or if fouled.

WARNING! Ensure ignition is off when testing; avoid electric shock.

Chain Brake & Clutch

Chain brake stops chain if kickback occurs; clutch engages chain at high rpm.

Chain Brake Inspection: Check band for wear; ensure handle moves freely; test activation.

Clutch Service: Remove clutch drum; inspect shoes for wear; clean centrifugal weights.

Sprocket: Replace if worn (teardrop shape indicates wear).

Engine Disassembly/Assembly

Major engine components: Cylinder, piston, crankshaft, bearings.

1. Remove top cover, air filter, carburetor, and muffler.
2. Separate crankcase halves after removing all screws.
3. Inspect cylinder for scoring; measure piston clearance (0.05-0.08 mm).
4. Reassemble with new gaskets; torque crankcase screws to 10 Nm (7.4 ft-lb).

CAUTION! Mark components for reassembly; use torque wrench for fasteners.

Carburetor Adjustment

Adjust idle, low-speed (L), and high-speed (H) screws.

1. Start engine; warm up for 5 minutes.
2. Set idle speed: Adjust LA screw for 2,800-3,200 rpm; chain should not move.
3. Adjust L screw: Turn clockwise until rpm drops, then counterclockwise 1/4 turn.
4. Adjust H screw: For max power without overspeed (do not exceed 13,500 rpm).

Note: Use tachometer for precise adjustment; follow EPA regulations for limit caps.

Parts & Torque Specifications

Component	Torque	Part Number (Example)
Cylinder bolts	20 Nm (14.8 ft-lb)	1128 030 2005
Clutch nut	40 Nm (29.5 ft-lb)	1140 640 2000
Flywheel nut	50 Nm (36.9 ft-lb)	1140 080 1600
Spark plug	25 Nm (18.4 ft-lb)	Bosch WSR6F
Guide bar nuts	10 Nm (7.4 ft-lb)	1128 664 4801

Parts Source: Genuine Stihl parts from authorized dealers.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine won't start	No spark, fuel issue, flooded	Check spark plug, fuel filter, lines; dry plug if flooded.
Engine runs poorly	Dirty air filter, carb adjustment	Clean/replace air filter; adjust carburetor L/H screws.
Chain doesn't turn	Clutch worn, sprocket damaged	Inspect clutch shoes and sprocket; replace if worn.
Excessive vibration	Loose components, unbalanced chain	Tighten all fasteners; sharpen chain evenly.
Oil not dispensing	Clogged oil passages, pump failure	Clean oil ports; check pump drive and lines.

Reset: For electronic ignition, ensure proper gap and connections.

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