This manual provides comprehensive workshop repair and service information for the ST50, ST70, CT70, and CT70H models, covering production years from 1969 through 1982. These iconic small displacement motorcycles are celebrated for their robust engineering, reliability, and versatility, bridging the gap between minibikes and full-sized motorcycles. The ST and CT series are noted for their user-friendly operation, with various transmission options including semi-automatic and manual clutches, making them accessible to a wide range of riders. Their enduring appeal lies in their simplicity, durability, and the foundational role they played in the legacy of quality small motorcycles. This workshop service repair manual is meticulously designed to empower owners and mechanics with the knowledge needed for thorough maintenance and repair. It covers a wide array of critical systems, including detailed engine overhaul procedures, fuel and transmission system servicing, electrical diagnostics, and frame and suspension maintenance. The manual offers systematic troubleshooting guides, precise technical specifications such as torque values and clearances, and clear explanations of routine maintenance tasks. With specific attention to model variations and year-specific addenda, this resource ensures users can effectively restore and maintain these classic motorcycles, covering everything from basic upkeep to complex component repair.