Yamaha YL1 rebuild

A 1966 Yamaha YL1 Twin Jet 100, engine L1-47603, frame Y33-47603: a 98 cc air-cooled parallel twin two-stroke with rotary valves and Autolube oil injection. Stripped down from November 2024 to January 2025. Assessment and the rebuild start in October 2026.

The YL1 as found, right side, in a garage doorway.

Instructions

Every job from the strip-down to the break-in, with its tools, parts, specs, checks and schedule.

Bike

The bike in 3D on any day of the rebuild, beside the photo taken nearest that day.

Reference