my LT makes a noise that is obviously nothing serious because it has done it for over 70,000 miles but it has always bothered me want it is. it's done it since the bike was new. it's a rattling sound when the bike is going slow and the engine is not pulling, like when going down an incline. i have checked the muffler and everything i can think of on the outside of the motor and there seems to be nothing loose,. Anyone now what this is?