me262 is correct. Engine is probably running too lean. But there is another option. If your bike is equipped with an air injection system, to lower emissions, which a 1979 should not be..., this makes the headers run hotter and blue. Another guess, is that the pipe manufacturer did not use a double-wall design, which usually solves this problem, and you may be able to return them... the reputation of the pipe manufacturer should be strongly considered, when purchasing pipes, as if a problem as this arises, they should be willing to back-up their product with a replacement or a refund.