When im cruising through town about 10 to 15 mph I,m getting a cracking or a poping sound from engine or exhaust. Im not sure if its the carbs or what. I drained all the gas and replaced spark plugs but it still happens. Its only ant low speeds. Once I throttle up it goes away. Its my first bike and I want to know If it is something common, or simple before I pay a dealer to look at it. Thank u hope someone can help