Motorcycle Chain Wear Checker

Rear wheel up (paddock stand), transmission in neutral: rotate the wheel to tension the lower run, then measure pin-centre to pin-centre across 20 pins with a steel rule or caliper. Many manuals give the service-limit length directly for 20 or 21 pins (e.g. '323 mm max over 20 pins' for a 520). Repeat at 3–4 chain positions — chains wear unevenly — and judge by the worst reading, also noting tight spots as you rotate.

As a quick screen, yes: grab a link at the rearmost point of the rear sprocket and pull away — if it lifts to expose more than about half a tooth, the chain is elongated enough to ride high on the teeth and deserves a proper measurement. It's coarse (sprocket wear affects it too) but it costs five seconds at every wash and catches neglected chains before they catch you.

The factory grease sealed inside the O-rings does the real lubrication; external care exists to protect the O-rings and the roller-sprocket interface: clean with kerosene/dedicated cleaner (never a pressure washer or wire brush, both murder O-rings), then a light film of O-ring-safe lube, excess wiped — it's corrosion protection and O-ring conditioning, not penetration. Adjusted correctly and kept clean, modern sealed chains routinely exceed 25,000 km; run dry and gritty, a quarter of that.

Almost always: by the time chain hits 1%, sprocket profiles have worn to match its stretched pitch, and a new chain on those profiles takes the old chain's wear pattern within a few thousand kilometres. The exception is early chain death by neglect on near-new sprockets (inspect tooth symmetry — if profiles are crisp and undamaged, the sprockets may honestly survive). When in doubt, the kit costs less than the second chain you'll otherwise buy.