Motorcycle Repair: 1979 Honda CB750K Limited Problems, 1979 honda cb750k, timing advance

Question
I volunteered to help out a friend and I'm stumped. He had others "fix " his problem!!! Well, when I unfixed everything it ran like hell except for one thing," it has CV carbs", when you rev past 5000 rpm, pull in the clutch it drops to 3000 rpm and hangs there for about 30 seconds and then drops back to idle.That might not seem like much but run on the edge and chop the thottle and your not tracking where you want to be. I'm use to pull slides and 170 speeds. He wants to keep up and not in a wheel chair. Please advise. Thanks in advance. E-mail me for more specfics if needed.

Answer
Robert, Take a look at the timing advance unit.  If you give the outer drum a quick twist does it snap smartly back to the zero advance?  If it hangs up or doesn't return at all, that would be my guess. It may need a new advance unit or I've adjusted the springs before. They relax sometimes but if you tighten them up too much you'll not have the right timing advance and the bike won't run as well as it should.  

Sorry for the late response, I've been out of town on vacation.  

Regards,
Rich