Secondary Air Supply System
The secondary air supply system introduces filtered air into exhaust gases in the exhaust port. The secondary air is drawn into the exhaust port whenever there is negative pressure pulse in the exhaust system. This charged secondary air promotes burning of the unburned exhaust gases and changes a considerable amount of hydrocarbons and carbon monoxide into relatively harmless carbon dioxide and water.
I presume this is what cincinnati dave, means??
google search, I've no idea whether doing this is a good idea or not, luckily mine runs smoothly with no backfires, etc.
CZ 360, DT175, xt600, fzr600, r1100gs, r1150r, drz400, f800gs, r1200gs, r1200gsLC, CRF1000L