here is my 2-cents the engine ran fine then it takes a nose dive you had to richen it up on the needle. and now it working great again, so your riding it.
What made it change? Could it be dirt in the mainjet or dirt in the float needle? dirt in the fuel tanks screen, all can starve the engine for fuel.
so your motoring along free as a bird and that little peice of what ever comes loose now you have a overly rich engine and you may be able to ride it home or you may have to pedal it.
I would find out just what is the problem then go for the rides, so you won't have to wonder when it going to act up again.
then ride it like you stole it.
your the guy I made the intake for? you might be running low on fuel as that intake would make my carb sit at an angle so you might need to adjust the float so the float lets in more fuel or it could be the float is sticking in the closed position if it keeps acting up I'll have to redo that carbs intake manifold. I remember your picture looked like the carb was sitting at mostly level in the pictures.