jet or float or ???

i haven't pulled the carbs off my seca in quite a while - that just ain't right.

here's what's going on: i have a stock airbox and a (mac?) 4-into-1 exhaust and i don't know if there is anything in the muffler.

i've increased the main jet to 124 (stock is 120) and shimmed the needes up with 2 washers. that worked great except for a stumble at just off idle.
i upped the pilot jets to 41's (stock is 40) and that worked great for 5 or 6 tanks of gas, then the bike REALLY started to complain at any RPMs. surging and backfiring. i added another washer to shim the needle and it got worse. so i took all the washers out and have been running with stock needle height and the larger jets.

performance wise, i'm quite happy with the bike. accellerates and runs good in all RPM ranges. a little flat between 5k and 6k, but i can live with that.

here's the problem: it seems like it's flooding when i try to start it. i've had the best luck starting it by first cranking with no choke. the bike immediately starts and idles pretty good for a couple seconds and then dies. then i give it full choke and start it again. this works 99% of the time. if i go straight to the choke it doesn't want to start and i can't get it started. a couple mornings where it was colder, i couldn't get it started at all. i put it on a battery tender and it started fine.

before the bike is warmed up it idles kinda rough with a very slight occasional backfire. once it's warmed up it runs and starts great.

theory 1 - weak battery - it's only 2 yrs old, but . . . the tender seems to have cured it. (i checked the bike charging system and all is well)

theory 2 - floats just barely too high. i've never had gas in the air box, but maybe the bottom of the carb throats are a puddle of gas? i've checked them with the clear tube method and they looked ok to me, but i was going for "as rich as possible but still ok" with the floats.

theory 3 - i solved a partially plugged off-idle circuit (the 2 tiny pin holes behind the butterfly that are fed by the pilot jet, but not directly under the pilot screw) by increasing the pilot jet size. now those holes have opened up causing me to get too much gas at low RPMs

anyhow - just wondering what other folks thought and if there's anything i'm missing.

the plugs are always just off-white on one side and light tan on the other side (nobody's been able to explain to my why my plug insulators are 2-toned either)