I just purchased a 1987 Aspencade SEI and discovered that it appears to be making an exhaust backfire noise on occastion. Sometimes the noise is more of a popping sound but most often it is a sort of wooshing sound and sounds like a metal plate is dragging for about a second. There are no other symptoms and the bike appears to have plenty of power etc... My uneducated guess would be that I should look to see if there are baffles in the exhaust system that need to be replaced. I´ve ordered a shop manual, but could use some ideas and guidance from someone who knows more than I do.