Just bought a 03 CRF450R & at low rpm's it sounds like there is something smacking twards the back left of the bike. Could this be REALLY loud chain slap when the motor is at low rpm's? If i'm gassing it the noise goes away. I checked the chain tension & it seems pretty good. Also the chain is a DID O-Ring chain & the sprockets arent worn at all so were not looking at stretched out junk here. Just wondering if anyone else has heard this? Thanks!