About the Yamaha DT125
A vintage DT125 year comparison that keeps the 1977–1978 fork gap visible.
For a DT125 restoration, keep separate entries for the engine, carburetor and forks. The featured engine gasket set lists 1977–1979, while the bowl gasket lists 1978–1981. Later DT125R and DT125RE models need their own full designation and product applications. The Yamaha DT family guide provides the other model routes.
Two fork sizes with a gap between them
The 1974–1976 fork-seal example measures 30 × 40.5 × 10.5 mm. The 1979–1981 option measures 32 × 44 × 10.5 mm. Neither establishes 1977–1978 fitment. Compare the actual fork and old seal dimensions before ordering, especially where a donor front end is fitted to an earlier frame.
Model and component differencesDT125 repair checkpoints
DT125, 1977–1979
Engine gasket set
Match the installed engine and gasket shapes with the joints being opened. A year covered by the engine set does not automatically have a matching fork-seal listing.
DT125, 1978–1981
Float-bowl gasket: 304-14184-00
Compare the bowl outline, screw pattern and gasket profile. This gasket seals the bowl joint; it does not replace the float or inlet valve.
DT125, 1974–1976
30 × 40.5 × 10.5 mm fork oil seals
Match all three dimensions and the profile to the fitted forks. Do not use an early listing to bridge the 1977–1978 gap.
DT125, 1979–1981
32 × 44 × 10.5 mm fork oil seals
Both diameters differ from the 1974–1976 seal, although the height is the same. A matching height alone is insufficient for selection.
Identify your motorcycle before orderingDT125 identification checklist
- Check the frame identity, model year and complete DT125 suffix against the motorcycle’s documents.
- Record engine and carburetor markings, especially where a replacement unit has been fitted.
- Compare the fitted fork assembly and original seal dimensions rather than bridging gaps between the listed years.
Contact PartsNMore with your model, year and clear photographs of the component and its markings.