Maintenance & Service ChecklistStandard Dimension Lookup — ID × OD × Height (mm)
Quick reference chart of motorcycle front fork oil seal dimensions and workshop installation steps.
Fork oil seals are standardized by Inner Diameter × Outer Diameter × Thickness (e.g., 26×37×10.5 mm for 26mm scooter forks, 31×43×10.3 mm for 31mm forks, 33×46×11 mm for 33mm forks). Recurring leaks after seal replacement are almost always caused by rust pits on the chrome stanchion or installing the double-lip seal upside down.
| Inner Tube Ø | Standard Oil Seal Size (mm) | Common Models | Fork Oil Volume (Typical) |
|---|---|---|---|
| Ø 26 mm | 26 × 37 × 10.5 mm | Aerox 155 V1, Wave 110/125, Click 125i | 55 – 65 ml per leg (10W fork oil) |
| Ø 30 mm | 30 × 40.5 × 10.5 mm | NMAX 155, YZF-R15 V2 | 70 – 85 ml per leg |
| Ø 31 mm | 31 × 43 × 10.3 mm | PCX 150/160, ADV 150/160, CB190R | 110 – 135 ml per leg |
| Ø 33 mm | 33 × 46 × 11 mm | XMAX 300, Forza 300/350 | 160 – 185 ml per leg |
Even a microscopic stone nick will slice the new nitrile rubber lip on the first compression stroke.
Wrap thin plastic film coated with fork oil over the top of the tube before sliding the seal down.
Click any part card below to open its full fitment dossier or search cross-references.
Include the motorcycle model, year, and OE part number if known. Verified notes are linked directly to part dossiers.