I bought the bike used back in October with no warranty. It is a 2011 Kingpin and it had 1700 miles on it when I got it---what I consider new. On the test ride it was a chilly day and when the bike was cold I noticed what seemed like high spots on the clutch. If you held the bike back and let out on the clutch slowly, it felt like it was jumping. After the bike warmed up it went away. The bike now has 3000 miles and while I was riding last week, it seems like it is doing it more and more. Not just when it is cold, but now even when it is warm. Then it goes away and comes back. Bike still shifts fine. When it gets really cold it does it really bad. Is this something I need to start worrying about? How much will it cost me to just go ahead and replace the clutch and is it something a backyard mechanic can do?