1979 Yamaha YZ100 Service and Repair Manual

Two displacements, one manual. Yamaha wrote LIT-11626-01-62 to cover both the YZ100 and the YZ125 for the 1979 season, and the YZ100 within it is model code YZ100F.

That pairing was normal for the period. The two machines were close enough in construction that the factory documented them together, calling out the figures that differ between them rather than printing two near-identical volumes. If a YZ125 of the same year is also in the workshop, this manual serves it too.

For a race bike the specification tables matter more than the prose. Port and cylinder measurements, clutch and transmission limits, torque values, ignition timing, carburettor settings and the wiring diagram are all as Yamaha published them, which is the reference point for deciding whether a worn part is still inside tolerance. Check YZ100F on the frame label before ordering.