1) Well my big bang at shut down is finally gone.  The final bit of advice that took care of that was the following from verslagen1:

"I've always found the biggest bang on shut down was when the idle mixture was set at optimum.  And all it takes to get rid of it is an 1/8 to 1/4 turn richer."

I turned it out 1/8 which helped and then 1/4 over optimum and that fixed it.  Thanks Versy!

2) Woke up to a foul odor in the house this morning and traced it to a large puddle of gas on the garage floor.  I had forgotten to shut off the standard type petcock on my old Honda CB and the tank emptied through the carburetor.  I took it apart and found the brass float filled with gas, it had a small crack in it and sunk to the bottom of the bowl.  Soldered it up and resolved to never again leave the petcock in the ON position.

3) After reassembling the carb on the Honda and admiring my fine work I noticed that the rear axle nut looked funny.  It was almost completely off the axle and the cotter pin was gone.  The wheel was somewhat cockeyed and about to fall off.  If the carb had not screwed up I would have taken it out for a ride.  From now on, safety check before leaving the garage.  Can't be lucky every time.

If only that CB had a vacuum petcock...
... then you wouldn't know that float had hole,... and you wouldn't have fixed it...
... and your rear wheel would still be free as a bird...

... are you sure you want to shut off your manual petcock?...
If you had....  wouldn't you be riding tomorrow with a sunk float, and gas spewing everywhere,... and how far from home?...
...(not to mention the loose axle)...
How many tools do you carry?...
That leak saved you from two, possibly deadly, roadside catastrophes...

Do you prefer a puddle in the driveway,... or a fuel splashed bike and pantlegs at 60mph sitting on a hot engine... and then,...no OFF position on your petcock... (do you trust that rubber vacuum diaphragm more than those brass floats?)...
'Tiss truly a choice a lesser evils...

I prefer the one I can turn off... and the one that will leak it's combustibles when I'm not sitting on it ...

JMHO... ...not really... it's more than just a humble opinion...
...

... (I might give exception for parking "indoors" as in an attached garage... and say best turn the manual pet, OFF...
... of course, the vac pet doesn't have that option... you must trust that the rubber diaphragm doesn't leak that day, because if it leaks, those floats don't matter anymore)...