carbon built around the valves in the head .....I don’t believe in spraying **** down something to get a quick fix. Never had success with that. If I have the head off, I might as well get it hot tanked to get everything clean. Including the valve that are probably coated in carbon built up
does the engine ever run as it should for very long, or does it die shortly after giving it throttle?
I doubt that you will find enough carbon that it warrants removing the head to have it cleaned... when the carbon around the valves gets heavy enough to cause problems, it is usally seen as a very weak and underpowered running condition because the valves are not fully closing... (which is very different than you are describing) this is about the only time the head needs to be removed specifically to clean the carbon deposits....
when I think I have a carbon problem in the cylinders, I use a spray bottle and spray water down the throat of the carb when the engine is to running temp and about 2000rpm.... and when I plan to take a tired but running engine down for a refresh, I will always run the water mist thru it to clean it before tearing into it...
and... a quick fix is much better than a long drawn out repair, and when the carbon is gone, its GONE, and it really doesnt matter how it got "gone" as long as it is no longer causing issues.
one thing that you said, "Now the engine wont turn over at all"..... Im reading this to mean that it no longer cranks over. this will either be an electrical issue or a hydrolock..... BUT, if you actually meant that "now it wont start at all", then this could still be electrical, but on a different circuit than the "cranking" circuit....
the other thing is, you said it "happened everytime I killed the engine".... does this mean you were intentionally killing the engine, and this happens, or that this is the event that happens that cause the engine to die?.... this will make some difference in where to look for the problem as well..
my vote is that you will find a fuel delivery issue, caused by any of the reasons already listed above... Less than 5psi of fuel is not a problem, UNLESS it is because no fuel is getting thru... one can see a LOT of fuel gushing out the line at 3 psi, and the engine should still run fine if its carbureted.
the fuel only needs enough pressure to push enough volume thru the small opening in the needle seat to feed the engine at any rpm it runs at.. if the volume isnt there (regardless of the pressure), the engine will starve for fuel and cause the type of running issues that you describe.
