Oil leak

You find oil stains under the bike, or seepage and greasy traces on the engine. Not all oil leaks are equal: the first, decisive step is to LOCATE precisely where the oil is coming from, since this determines both the severity and the difficulty of the repair. Causes range from harmless to serious. The most common and simplest: a poorly tightened drain plug or oil filter (or a crushed/forgotten gasket), typically right after an oil change. Next come a case or cover gasket (cylinder head cover, ignition/clutch cover) that hardens and seeps over time, a leaking shaft seal — the fork seal deserves particular attention since oil on the tube reaches the disc and pads (a braking hazard), while the gearbox output seal soils the sprocket and chain — and finally, rarer and more serious, a leak at the head gasket. You tell them apart by pinpointing the source: fork tubes/front wheel? lower engine/covers? between the head and cylinder? and by noting whether the leak followed an oil change. Urgency threshold: a small leak that soils without lowering the level isn't urgent, but a significant leak (draining the sump and threatening oil pressure) or a fork leak oiling the brakes needs addressing without delay. Always keep an eye on the oil level: as long as it stays correct, you can ride carefully; if it drops, don't ride. And clean the engine to better locate an active leak: on a clean block, observed after a short ride, it's much easier to spot where fresh oil reappears, avoiding guesswork disassembly.