1981 Yamaha DT50, DT80, DT50MX, DT80MX Service Manual

Yamaha DT50, DT80, DT50MX, DT80MX 1981 Service Coverage

• Covers 1981 Yamaha DT50, DT80, DT50MX, and DT80MX lightweight dual-sport motorcycles featuring the Yamaha Monocross suspension system
• Official Yamaha publication, 1st Edition dated March 1981
• Contains 100 pages of illustrated technical content including exploded-view assembly diagrams, electrical schematic figures, and diagnostic test procedures
• Stored against your account so you can retrieve it after a hard-drive loss
• OCR text layer lets you jump to a torque spec by keyword
• This 1981 first edition is the primary reference used for the initial launch build of the Yamaha DT-series MX variants

Mechanical and Chassis Documentation

The 1981 Yamaha DT50/DT80 service manual documents the complete Monocross suspension system, covering operation principles of the floating MX valve and high-pressure nitrogen gas chamber. Engine coverage includes detailed data on piston clearance, ring-end gaps, and crankcase disassembly. Service sections detail the multi-plate clutch assembly, including wear limits and tightening torque values for clutch boss components. The chassis section provides specific dimensions for brake shoe wear limits and front fork oil servicing, complete with required oil quantities and types.

Electrical and Diagnostic Specifications

Electrical data features diagnostic reference values for ignition coil resistance and lighting system voltage outputs across the specified model variants. Charging system documentation provides testing guidelines for battery specific gravity and regulator function, along with detailed wire harness routing diagrams. what an OEM service publication covers includes primary ignition coil resistance specified at 1.0 ohms ± 15% in the ignition system table. Secondary ignition coil resistance is documented at 5.9 k ohms ± 15% in the electrical troubleshooting data. The standard cylinder bore diameter for the 1981 DT50MX is referenced at 40.00–40.02 mm in the cylinder specification data. Reference only — always consult a certified technician before performing service on this equipment.