Motorcycle Questions? Ask a Mechanic.
Hi and welcome to JustAnswer,Thank you for the question and your patience. Should you still need assistance for information purposes only...Initially and almost always, the described "...hunt...idles too high..." with a "...carbs are clean..." would point to a most likely vacuum leak; i.e. after the carb to the intake (manifold).
Other than to re-check the coupling, check the spark plug burn. It black and sooty, then the overly rich/vacuum leak is confirmed.
A leak in the crank seal would also affect the compression. Consider a compression or better yet a leakdown test.
Yes please; an update when able on the compression test.
...and the color of the sparkplug(s).
Then consider spraying with water the intake area.