When idling and when you give it throttle it quite literally sounds like a lathe cutting metal (look it up!). The noise is quiet but noticeable if you listen. It is not obscenely loud but you can tell. It' s kind of concerning, but the thing has had a fair share of ride time and it has not gotten worse. I just really don't like it but have no time to investigate. Anyone have a clue what this could be to point me in the right direction when I one day get to look at it? Also has anyone put a K and N filter on their bike? I need to jet mine because the thing has no balls when you on the throttle and runs too rich, any advice is much appreciated