This workshop service manual provides comprehensive information for STIHL BG 56 / 66 / 86 and SH 56 / 86 models, powered by efficient 2-stroke petrol engines. These units are engineered for reliable performance in demanding applications. The manual covers models with engine displacements ranging from 40.2 cm³ to 63.3 cm³ and power outputs from 1.4 kW to 2.9 kW, featuring electronic ignition and diaphragm carburetors. Their robust construction and user-friendly rewind starters ensure operational readiness for various tasks. This English-language manual serves as an essential resource for maintaining and repairing your STIHL equipment. It details critical maintenance procedures, including air filter cleaning and spark plug replacement, alongside troubleshooting guidance for common issues related to starting, idling, power, ignition, and fuel systems. Technical specifications and safety guidelines are also included, empowering owners, mechanics, and technicians to ensure optimal performance and longevity of their BG and SH series units.