My 04 YFZ 450 won't start after sitting for a few weeks without running. The oil from the oil tank drains slowly into the engine. Oil level barely showing on the stick but after finally starting it (by towing it behind my car) the level rises to normal. My buddy's Harley won't start either when all the oil has drained into the engine. Apparently this is a common problem with old Harleys. Could the oil in there keep the engine form starting in the YFZ? Has anyone noticed the oil draining like this?? I will be changing the sparker in the next coupla days...will see if that helps.