All good. Slide was sitting too high in the carb, giving a closed throttle lean condition. Weird, as the bike was idling fine at a/s 1.5.
Rode this morning 14c, 100m ASL, NEDW#3, 42p/175m, a/s 1.5, Motul 710 @ 2% in 98RON.
Smooth, quiet & grunty power all the way. Case closed, nothing to see here, very, very happy this saga is over!
Keg, thanks for your help with TSP/pistons/etc, etc.