I've had this bike for about a year now, but it's always made this noise when in gear and under load (doesn't need to be much, but if the engine is pushing the bike, it makes this sound). It seems to come from the gearbox or lower part of the engine, and is more pronounced on the left side of the engine.
There's also a bit of a 'whir-whir-whir' sound which can be heard at highway speeds - might be realated. The whirring sounds like a bearing issue, but I don't know about this one. Any ideas?
