I have a 05 zx-10 and was at a gas station with only regular and running on fumes so i put 10 buck in to get me by. before the tank was out it, the bike had a deep cruiser-like sound. backfires when off the throttle at +6000rpm. major power loss, sloppy idling. got about 6 tanks burnt since. I am thinking i fouled a plug or something. anybody been here of have some suggestions?