my 03 wr450 just started acting up. the temperature has dropped lately to about 45-55 degrees outside and it seems to have been doing it since its got colder out. also for some reason it seems to stay idling high when im going down hills. i think that might have had something to do with hot start lever being messed up though. i know the motor is getting tired so im wondering if it has something to do with that. it was been running a tad rough for a little bit now but no real signs of metal or anything in the oil so i have just been running. what else would cause the higher piched popping(doesnt seem like a full on backfire, just a louder sputtering). its never really done that until yesterday. thanks for any advise.