Your engine seems to run better on 16:1 because that's actually making it run lean!!!
(more oil = less gas in every drop of fuel)
Use 32:1 & then jet the carb.
oh trust me it ain't running lean. i've rejetted with every new mix i try and plug chop multiple times. i bought 21 piece jet set, from #80 on down. when i first got the bike, i was running leaner than a starving lot lizard. caused me heat issues( which i kept throwing oil at, and found i was wrong in tht aspect, without rejetting). an was solved by help from you and others on here. then i bought some two stroke engine books and did a lot of reading. been playing with oil ratio's and found the 16:1 not only runs the coolest, but makes the most power. just drips after shut off, to much for my taste, that and i don't really beat my bike. 20-24:1 i get a few drips after shut down, no smoke but maybe a wisp, and the temps stay nice and cool. i've tried every jet from #68 on up and played with every mix from 8:1 to 32:1. any jet under #68 and it just won't run. any jet smaller than a #70 and my temps get to hot for my taste. i love playing with this motor and will spend hour and hours on weekends tinkering with it, from spark gap to oil mix to jets. tried some different carbs too, still prefer the nt and nt clones for simplicity, and the available jet kits at a good price. an thanks to you venice, i will be getting a fred head for my next build, it's gonna be my speed racer engine, gonna port, pipe, magneto, pick up coil, fred head it , etc. i get my best power with #72-73 jet and 16:1, but i also get 3 tablespoons or so of spooge at shut off, not much smoke though. i'm currently running a #70 at about 24:1, great power, bit less then 16:1, #71 makes a lot of four stroking at 24:1 ( all the way through the throttle, i can get most of it to go away with a needle dropped to position 5 but at full throttle its four stroking.), which is why i dropped it down to a #70 and am sitting on position 3 on the needle. little four stroking till it warms up, then it's zoom zoom zoom.
edit: also i took an endoscope inside, and the crank has a slight sheen of oil on all the parts, and cylinder is clean as the day i bought it.
oh and i'm in middle america around 2300 feet above sea level.