OK, it seemed to have been a cumulative effect of pretty much everything being mal-adjusted by the monkey who wrenched on the bike before I bought it- each thing I did, it helped make starting the beast a bit easier. I was amazed. If it could be tinkered with without breaking the engine open, it was out of adjustment enough to be impossible to cold start... and run like sh&te when it did light up.

Order of adjustments I undertook:
1. check proper spec, clean & gap the spark plug; check for spark.
2. adjust cold start/choke knob cable - in HOT Bangkok, you never need to pull the knob fully up. turns out half-way engaged is perfect for cold starts here. fully choked is worse than no choke.
3. adjust throttle cable slack - was so loose, I believe the choke wasn't able to usably raise the throttle for cold starts.
4. adjusted oil pump - unrelated to the starting problem til I radically adjusted the throttle cable slack... which affected oil pump calibration in a big way.
5. RC valve & servo check & adjustment; the system was so far out that the cables were slack, barely hanging onto their pulleys. valve was basically stuck close to the high rpm position, destroying low rev power, and making port timing for starting non-optimal.
6. checked & cleaned all electrical connections.

Many signs of idiocy by previous owner's hired wrench. Upside is now I KNOW this bike inside & out, and have confidence in it enough to take it on the road. No regrets at all. Thanks to all for throwing me a rope with this bike!
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-bdb