Re: Standard upgrades?
Spark plug NGK B5 6 or 7 HS (B6HS) is the good medium range plug, better NGK plug boot, stock ones are junk normally dont last very long and then they fall apart at a bad time usually, a better exhaust is always top of my list and I pull head and jug and upgrade the wrist pin bearing, i've had two major failures and both were due to cheap junk bearings, after 150 or so miles I start the carb tuning process after I install the exhaust and air filter I plan to run and have settled on the brand of oil and the ratio I plan to run.
These few upgrade will make a big difference in performance and reliability in my experience, if you can I would do three things before ever mounting the engine and running it, get the better spark plug get the NGK or another good plug boot replace cheap wrist pin bearing with better one these three things will only cost you about $20 or maybe a little lessbut will help the reliability of the engine while its breaking in, then I'd go to a better flowing exhaust and tune the carb to lean the mixtire down some because these engine are known to run fairly rich out of the box and 4 stroke a lot.
Im sure you'll get other opinions here and thats fine but I know from experience the things I listed are worth doing right from the get go and many others here do at least some of the same when they get a new engine.