5 quick operation and Maintenance Qs

I think just because you are paying attention to it, it'll live longer but...
If you ever do hear a bottom end knock, shut it down. These engines are notorious for poking the #5 rod right through the left side of the block.
Clogged PVC is very often carbon build up in the steel tube at base of carb where rubber hose is attached. Replacing hose, valve, all is good but also use a drill bit to clean out that steel tube.
Adjusting valves while running is a fun experience. Get'er warmed up then idle down low as it will go, Snatch the cover off and ride the rockers, long goose neck end wrench in one hand, feeler gauge in the other. By the time you get the hang of it you'll wish there were a dozen more in there to adjust.