Bikes were reported to leak oil on the rear left side. For most bikes this is not a leak: this is chain lube. It collects in the pinion cover and runs down the engine. The chain out of the factory is coated with a very fine oil that is very liquid when warming up. As long as you don’t see the oil level decrease in the engine just forget about it and ride.

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But is seems that a small number of bikes may be affected by a leak from the oil sump gasket.