My 05 Virago has been sitting in the garage for easily three years unattended. Amazingly the battery still had a smidgen of a charge. Once re-charged completely and the gas replaced I got it running, sort of. The reason I parked it originally was the front cylinder wasn´t firing and I didn´t have time to mess with it. Now, after sitting, the front works fine but the back cylinder is dead. Any thoughts on the culprit?