STIHL 064 Repair Manual

The STIHL 064 is a professional-grade chainsaw known for its power and durability. This repair manual provides comprehensive guidance for maintenance, troubleshooting, and repair procedures. It covers engine systems, fuel system, ignition, chain brake, lubrication, and electrical components. Always prioritize safety: wear protective gear, work in a well-ventilated area, and disconnect the spark plug before servicing. Below are key sections for specifications, safety, disassembly, repair procedures, and troubleshooting.

Specifications & Technical Data

Key technical specifications for the STIHL 064 chainsaw.

Specification	Value/Description
Engine Type	2-stroke, single cylinder, air-cooled
Displacement	64.1 cc (3.9 cu. in.)
Power Output	4.4 kW (6.0 HP)
Fuel/Oil Mix Ratio	50:1 (STIHL HP Ultra or equivalent)
Ignition System	Electronic, breakerless
Carburetor	STIHL HD (adjustable H, L, LA screws)
Chain Pitch	3/8" or .404" (depending on configuration)
Guide Bar Length	Typically 20" to 36"
Weight (powerhead only)	Approx. 7.3 kg (16.1 lbs)
Spark Plug	Bosch WSR6F or equivalent, gap 0.5 mm (0.020")

Safety Precautions

Always follow safety procedures to prevent injury or damage.

1. Personal Protective Equipment (PPE): Wear chainsaw chaps, gloves, eye protection, hearing protection, and steel-toed boots.
2. Work Area: Ensure clean, well-lit, and ventilated space. Keep away from open flames or sparks.
3. Before Service: Allow engine to cool. Disconnect spark plug wire and secure it away from plug.
4. Fuel Safety: Drain fuel tank before major disassembly. Wipe up spills immediately.
5. Sharp Components: Handle chain, sprocket, and cutter parts with care; wear cut-resistant gloves.

WARNING! Failure to follow safety instructions can result in serious injury or death. The chainsaw must be completely de-energized before any repair work.

Tools & Special Equipment

Recommended tools for servicing the STIHL 064.

1. Standard Tool Set: Screwdrivers, wrenches (metric), Torx bits (T27), socket set.
2. Special STIHL Tools: Flywheel puller (1110 890 4500), piston stop (1110 890 4000), clutch removal tool (1110 890 4100).
3. Measuring Tools: Feeler gauges, compression tester, multimeter.
4. Cleaning Supplies: Carburetor cleaner, parts brush, compressed air.
5. Torque Wrench: For critical fasteners (cylinder bolts, clutch, flywheel).

CAUTION! Use correct tools to avoid damaging components. Do not substitute improper tools for STIHL special tools where specified.

Engine Disassembly & Assembly

Step-by-step procedure for engine teardown and reassembly.

1. Preparation: Drain fuel and bar oil. Remove bar, chain, and side cover.
2. External Components: Remove starter assembly, air filter cover, carburetor, and muffler.
3. Crankcase Separation: Remove all screws securing crankcase halves. Gently separate halves using a plastic mallet if necessary.
4. Crankshaft & Bearings: Inspect bearings for smooth rotation. Replace if rough or noisy.
5. Reassembly: Apply sealant (STIHL Dirko or equivalent) to crankcase mating surfaces. Torque screws in a crisscross pattern to specification (typically 10 Nm).

Tip: Take photos during disassembly to aid reassembly. Keep small parts organized in labeled containers.

Cylinder & Piston Service

• Compression Check: Should be above 120 psi. Low compression indicates worn piston/cylinder.
• Cylinder Inspection: Check for scoring, aluminum transfer, or glaze. Light honing may be possible; severe damage requires replacement.
• Piston Inspection: Look for scoring on skirt, ring groove wear, or damaged ring lands. Replace piston and rings as a set.
• Piston Pin & Bearings: Check for play. Replace needle bearing and circlips during reassembly.
• Deck Clearance: Measure with feeler gauge; specification is 0.5-0.7 mm.
• Ring End Gap: Place ring in cylinder, measure gap; should be 0.3-0.5 mm.

Carburetor Adjustment & Repair

STIHL HD carburetor service procedures.

Initial Settings (screws turned gently to stop, then backed out): L screw: 1 turn out. H screw: 1 turn out. LA (idle speed): 1 turn out.

Final adjustment requires tachometer: Idle speed: 2,800-3,200 RPM. Maximum speed (no load): 13,500 RPM. WARNING! Over-revving can destroy engine.

Diaphragm & Gasket Kit: Replace if carburetor leaks, saw runs poorly, or diaphragms are stiff/cracked. Clean all jets and passages with carburetor cleaner and compressed air.

Ignition System

Testing and replacement of ignition components.

1. Spark Test: Remove spark plug, connect to wire, ground plug base to cylinder. Pull starter; look for strong blue spark.
2. Coil Air Gap: Adjust between flywheel magnets and coil legs to 0.3 mm (0.012") using a feeler gauge.
3. Resistance Check: Primary coil resistance: ~0.5-2.0 Ω. Secondary (spark plug wire to ground): ~5-15 kΩ.
4. Switch & Wiring: Check kill switch for continuity when off. Inspect all wires for breaks or chafing.

Tip: Weak or no spark often indicates a faulty ignition module. Replace with OEM STIHL part.

Chain Brake & Clutch

Servicing the chain brake and clutch assembly.

1. Chain Brake Function Test: With engine off, activate brake handle; chain should lock immediately.
2. Brake Band Inspection: Replace if worn thin or cracked. Clean around clutch drum.
3. Clutch Removal: Use STIHL clutch tool to hold drum, turn clutch nut clockwise (left-hand thread) to remove.
4. Clutch Shoes: Check for excessive wear, cracking, or glazing. Replace as a set.
5. Needle Bearing: In clutch drum should spin freely. Replace if rough.
6. Reassembly: Torque clutch nut to 40-50 Nm. Ensure brake spring is correctly positioned.

WARNING! Do not operate saw with a malfunctioning chain brake. It is a critical safety device.

Fuel & Oil Systems

Fuel tank, lines, filter, and automatic oiler service.

Fuel System: Replace fuel filter annually or if clogged. Inspect fuel lines for cracks, stiffness, or leaks. Use STIHL-approved fuel line. Ensure tank vent is clear.

Oil System: Check oil pump output by running saw at high idle over cardboard; should produce a line of oil. Adjust oiler screw if adjustable. Clean oil tank pickup filter. Ensure oil passages in bar pad are clear.

CAUTION! Use only high-quality, fresh 2-stroke oil mixed precisely to 50:1 ratio. Old or improper fuel mix is a leading cause of engine failure.

Electrical System

STIHL 064 uses a magneto ignition system. No battery or charging system is present.

Component	Function & Test
Ignition Module	Generates spark. Test as per section 8.
Kill Switch	Grounds ignition to stop engine. Should show continuity when pressed.
Spark Plug Cap	Internal resistor (~5 kΩ). Replace if cracked or resistor fails.
Wiring Harness	Inspect for damage, especially where it passes through handles and mounts.

Troubleshooting Guide

Symptom	Possible Cause	Corrective Action
Engine will not start	No spark, flooded, fuel issue, compression	Check spark, plug condition. Dry plug if flooded. Check fuel lines, filter, carburetor. Test compression.
Engine starts then dies	Fuel starvation, air leak, carb adjustment	Check fuel vent, filter, lines. Pressure test crankcase for leaks. Adjust carburetor L screw.
Lacks power under load	Clogged air filter, muffler screen, carb H setting, compression	Clean/replace air filter. Clean spark arrestor screen. Adjust H screw with tach. Check compression.
Chain does not oil	Empty oil tank, clogged passages, faulty pump	Fill tank. Clean bar oil holes and tank filter. Check oil pump drive and adjust/output.
Excessive vibration	Loose components, unbalanced clutch, bent crankshaft	Tighten all mounts, bar nuts, handles. Inspect clutch shoes. Check crankshaft runout.
Chain brake does not engage	Broken spring, worn band, dirty mechanism	Inspect brake band and spring. Clean around clutch drum. Replace faulty parts.

Reset: After major repairs, retune carburetor from initial settings using a tachometer.

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