Stihl HS 45 Parts Manual

The Stihl HS 45 is a lightweight, professional-grade hedge trimmer designed for precision trimming and shaping of hedges and shrubs. This parts manual provides detailed information on the components, assembly, maintenance, and replacement parts for the HS 45 model. Below are key sections covering safety, parts identification, assembly instructions, maintenance procedures, and ordering information.

Parts Identification

Key components: Engine housing, Cutting blade assembly, Handle with controls, Throttle trigger, Stop switch, Fuel tank, Air filter cover, Spark plug, Muffler, and Carrying strap attachment points.

Part Number	Description
1140 790 3800	Cutting Blade Assembly (Complete)
1140 790 3801	Upper Blade
1140 790 3802	Lower Blade
4134 790 0800	Throttle Trigger
4228 790 0800	Stop Switch
1140 141 0600	Air Filter Element
1140 140 0603	Spark Plug (Bosch WSR6F)
1140 140 0601	Fuel Tank Cap
1140 790 3805	Handle Grip
1140 790 3806	Carrying Strap

Safety Information

Always read the operator's manual before use. Wear appropriate personal protective equipment (PPE).

1. Clear work area of bystanders, especially children.
2. Inspect the hedge trimmer before each use for loose parts or damage.
3. Ensure the cutting blades are properly lubricated and sharp.
4. Use only STIHL-approved replacement parts and accessories.

WARNING! Never operate a damaged or improperly assembled hedge trimmer. Risk of serious injury or death. Disconnect the spark plug before performing any maintenance.

Assembly Instructions

Assemble the handle, cutting blade, and controls as follows.

1. Attach the handle: Align the handle with the mounting points on the engine housing and secure with provided bolts (M6 x 25mm).
2. Install the cutting blade: Slide the blade assembly onto the drive shaft, ensuring the teeth face away from the operator. Secure with the blade retaining bolt (M8 x 20mm) and tighten to 15 Nm.
3. Connect the throttle cable: Route the cable from the trigger to the carburetor lever and secure the retaining clip.
4. Attach the carrying strap: Hook the strap ends to the front and rear attachment points on the housing.

CAUTION! Ensure all fasteners are tightened to the specified torque. Loose components can cause vibration and failure.

Technical Specifications

• Model: HS 45
• Engine Type: STIHL 2-MIX engine, single-cylinder two-stroke
• Displacement: 27.2 cm³
• Power Output: 0.8 kW (1.1 hp)
• Fuel/Oil Mix: 50:1 (STIHL HP Ultra oil)
• Cutting Blade Length: 60 cm (24 inches)
• Tooth Spacing: 20 mm
• Weight (without cutter bar): 4.9 kg (10.8 lbs)
• Sound Pressure Level: 94 dB(A)
• Vibration Level (left/right): 4.5/5.5 m/s²

Maintenance & Lubrication

Regular maintenance ensures optimal performance and longevity.

Daily: Clean air filter, check blade sharpness and lubrication. Weekly: Inspect spark plug, clean cooling fins, check all fasteners. Monthly: Clean fuel filter, check fuel lines for cracks.

Lubrication: Apply STIHL hedge trimmer oil to the cutting blades before and during operation via the lubrication port. Grease the drive shaft splines every 25 operating hours with STIHL Polyurea grease.

Cutting Blade Assembly

The dual-sided blade cuts on both the forward and return strokes.

1. Blade Removal: Remove the blade retaining bolt and washer. Slide the blade assembly off the drive shaft.
2. Blade Sharpening: Use a round file (4.5 mm diameter) to sharpen each tooth at the original angle. Maintain equal tooth length.
3. Blade Installation: Align the blade drive hole with the shaft splines. Reinstall the washer and bolt, tightening to 15 Nm.
4. Blade Guard: Always install the blade guard for storage and transport.

WARNING! Always wear heavy-duty gloves when handling cutting blades. Blades are extremely sharp.

Engine Components

Key engine parts: Cylinder, Piston, Carburetor (Zama C1Q-S139), Ignition Module, Fuel Pump, and Muffler.

1. Air Filter Service: Remove the cover, take out the foam filter, clean in warm soapy water, dry, and re-oil with STIHL filter oil.
2. Spark Plug: Check gap (0.5 mm). Replace if electrodes are worn or fouled.
3. Fuel System: Use fresh fuel mix. Clean the fuel filter in the tank every 3 months.
4. Muffler: Remove spark arrestor screen periodically and clean carbon deposits.

Tip: For engine troubleshooting, refer to the separate engine service manual.

Handle & Controls

The ergonomic handle houses the throttle trigger, stop switch, and throttle lockout.

Component	Function	Part Number
Throttle Trigger	Controls engine speed	4134 790 0800
Stop Switch	Stops the engine	4228 790 0800
Throttle Lockout	Safety lever that must be depressed to operate throttle	4134 790 0801
Handle Grip	Provides comfort and vibration damping	1140 790 3805
Control Cable	Connects trigger to carburetor	1140 790 3807

CAUTION! Never modify or bypass the safety controls. The throttle lockout is a critical safety feature.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine will not start	Old fuel, clogged filter, faulty spark plug	Use fresh fuel mix, clean/replace air & fuel filters, check/replace spark plug.
Engine runs poorly or stalls	Dirty carburetor, air leak, fouled spark plug	Clean carburetor, check intake manifold gasket, replace spark plug.
Excessive vibration	Loose blade, worn blade bearings, unbalanced blade	Tighten blade bolt, replace blade bearings, sharpen blade evenly.
Blade does not move	Sheared drive shaft key, clutch failure	Inspect drive shaft and clutch assembly. Replace damaged parts.
Overheating	Clogged cooling fins, lean fuel mixture	Clean cooling fins, adjust carburetor to factory settings.

Reset: For electronic ignition issues, disconnect spark plug wire for 1 minute to reset module.

Parts Ordering

Always use genuine STIHL parts to maintain performance, safety, and warranty coverage.

1. Locate the 10-digit part number from the illustrations or lists in this manual.
2. Contact an authorized STIHL servicing dealer.
3. Provide the model (HS 45) and serial number (located on the engine housing).
4. For online reference, visit the STIHL USA parts catalog (parts.stihlusa.com).

Note: Some parts are sold as assemblies only. Consult your dealer for availability.

Warranty Information

STIHL Limited Warranty: The HS 45 is covered by a 1-year limited warranty for personal use from date of purchase. Commercial use may have different terms. Warranty covers defects in materials and workmanship. It does not cover damage from misuse, neglect, improper maintenance, or use of non-STIHL parts. Proof of purchase is required.

For warranty service, contact the authorized STIHL dealer where the product was purchased or visit www.stihlusa.com for dealer locator and support.

Service Hotline: 1-800-467-8445