1977 Kz200 High idle issue

Hi,

I've got a 1977 Kz200 that I found sitting in a garage, was torn apart to replace a head gasket in 1987 and never put back together until now. It's up and running but it's idling at about 3000-4000 in neutral and I'm not sure why. It goes down when I adjust the air screw almost all the way out, but as soon as I rev, it goes back up and sticks. Any and all
suggestions welcome.

This problem has been discussed many times on this forum. Give the search function a try.

In short, there are several possibilities. Among the more common are-
- air leaks where the carb holder bolts to the head.
- air leaks where the carb goes into the carb holder.
- air leaks through cracks in the carb holder.
- a sticking throttle cable.
- a sticking timing advancer.
-a missing or disconnected air filter box.