Hi everyone. Whenever I start up my girlfriends bike, the bike will idle high and randomly and slowly go to a normal idle rpm. If I play with the "idle screw" it has no effect on it at first then will drop to low and die. The problem seems to be not as severe when bike is warm after riding it. Went threw the carb and checked valve clearances and jetted for altitude (Iowa) this winter. Any one have this similar problem??