Hi this is my first post here and Ive just bought a near new 08 YZ450F with a Pro Circut T1 Muffler as the only modification. The gearing is standard 13/49 and the bike goes ok in general but the chain chatters annoyingly down low until the revs rise. The chain IS adjusted correctly. This is my first 450 after coming off a 250 2stroke and to me the gearing feels way too tall compared to my old bike. Does any of this seem normal for this bike? Thanks for any help guys..