The bike I´m looking at seems to be in pretty good shape but the thing I´m wondering about is that the owner say´s the bike is hard to start and takes roughly 15 minutes to warm up before it runs smooth....once it is warm there is lots of power....he say´s it is hard to start and takes long to warm up because the carb´s need to be cleaned.....does this sound correct?.....does anybody have a thought on this sympton?.....thanks