I have a problem with my K bike idling.  I turned up idle adjustment and didnt help.  Looked for external leaks I could check including using propane gas to ID leak but not leak found.  What are the areas where K bikes can develop air leaks which are not easily visible?  thanks

The S shaped breather pipe behind the throttle bodies is known to crack and create issues about idling.
The pipes from the throttle body to the head can also crack or leak.
Check them. 
But most of problems come from messed synchronization of the throttle bodies.
First of all, service the whole engine, new oil, valve clearance checked and adjusted, new plugs.
Synchronize the removed throttle flaps by using 2 identical rods: all the flaps must move identically.
Then you need to adjust the air screws to synchronize them with engine running at service temperature, using a depression device.

As a matter of routine I would replace the vacuum caps, the vacuum line from no 4 to the fuel pressure regulator and also the S or Z crankcase vent that goes into the airbox. You may also have a vacuum pipe from no 1 to a vacuum sensor, you can eliminate it and use another vacuum cap on the spigot.

Once you have those right check the balance as suggested but also the throttle position sensor.

That sorted my RT when I had issues.

You can get leaks at the throttle body to cylinder head but the others above are the more likely causes.

While you are at all that if your tank to fuel rail hoses are original replace them. They go hard and lots of wriggling moving the tank around can crack them.