I got a 2004 yz250f and whenever i let off the throttle and coast the bike makes crackling and popping noises out the exhaust. If i give it the slightest amount of gas it goes away. The noise is much louder than most other thumpers that i've heard. It has a pro circuit ti-4 exhaust system on it but it does the same thing with the stock exhaust system. Any help is appreciated.