This system (First introduced in 1979) called the Clean Air System, on the MKII KZ1000 and the 1300. Thereafter on all models, and currently is on all Kawasaki Models and Engines in almost the same configuration, as introduced 35 years ago.
What I am saying goes counter to the above posts but here you go.
The system does work and robs almost no horsepower from the Engine. If left in place it requires little to no maintenance.
The largest headache with the system is access to the valve cover. But in the end is very easy to remove and reinstall.
The vacuum switch and reed valves can cause backfiring if they get dirty or malfunction. The factory shop manual provides very detailed diagrams, and gives a good description of how it works, and how to maintain it.
In short, it injects clean (filtered air from the air box) into the exhaust stream, at the base of the exhaust valve.
When I raced my KZ1000 in the 80's this was the first system to come off the bike. If they were daily drivers, I left the system in tact, so as to keep the engine burning as clean as possible.
