Got a 2003 cobra 50 2t. With 9000miles. I can only get it to start after I hear a high pitch whine coming from the battery compartment. The sound is very intermittent and takes several attempts of turning the key on and waiting and/or trying to turn it over with the kick/starter. The battery is a little weak. Usually between 12.7-9v. Is the cdi making this sound? Does it need some extra charge by the battery? Anyone come across this problem?