🏷️ Basic Information Identification Make: Stihl Model: 021, 023, 025 Generation: N/A 📋 Manual Details Publication Manual Type: Workshop Service Repair Manual Language: English Format: PDF Download Scope Covered Topics: Troubleshooting, repair, assembly, disassembly, maintenance, specifications, parts diagrams ⚙️ Engine Specifications Engine Type Engine Type: 2-stroke gasoline engine Displacement Displacement 021: 31.8 cc Displacement 023: 40.2 cc Displacement 025: 45.0 cc Power Power Output 021: 1.5 kW (2.0 hp) Power Output 023: 2.0 kW (2.7 hp) Power Output 025: 2.3 kW (3.1 hp) 🔧 Transmission Drivetrain Type: Direct drive via centrifugal clutch Gears: N/A (single speed) 📐 Dimensions Physical Bar Length Options: 10" to 16" (25cm to 40cm) Weight Without Bar And Chain 021: 4.3 kg (9.5 lbs) Weight Without Bar And Chain 023: 4.4 kg (9.7 lbs) Weight Without Bar And Chain 025: 4.5 kg (9.9 lbs) 🔧 Maintenance Lubrication Oil Type Engine: Stihl HP Ultra or equivalent 2-stroke oil Fuel Oil Ratio: 50:1 (with Stihl HP Ultra) Oil Capacity Chain Lubrication: 0.15 L (5.0 fl oz) General Spark Plug Gap: 0.02" (0.5 mm) Chain Tensioning Procedure: Side chain adjuster