Hi everyone, I recently acquired a 2001 zx6r J1. Initially the bike ran fine, I have put about 500 miles on it since I got it. One day, out of the blue, started the bike and the exhaust sounded really low pitched like a v twin. The bike ran but would not go over about 10,000 rpm's. All I know from the last owner is that it was used on the track at one time, has had a valve adjustment 3,000 miles ago, has been down but repaired, he hadn't done any work to the carbs, and it has an aftermarket exhaust. The day the bike started acting weird I did nothing out of the ordinary. I fueled up at my regular station, rode 60 miles on the highway, stopped for a half hour and then.. wtf? Has anybody had this issue? also any ideas? Thanks.