TE/TC TE300 - starting anomaly...?

2014 TE300 @5K miles.
Just rebuilt with mains, rod, piston, rings, all gaskets and so on, replaced jets (new for old, same jetting as previously) Running NECJ needle.
Here's the thing. The bike is a little rich. It never used to be anything but spot on, even if I say so myself !! This I put down to the fact that I am riding in warmer conditions than I usually do. Im a winter rider really....
When I tried the first time after the rebuild, I couldnt get her to fire with the kicker. I resorted to the electric start and bingo, first time. no problems...Idles much better than it ever has ( still does ).
Now though, ever since the rebuild and some 20+ hours on, it will not fire if I use the electric starter...! Recent new starter motor, upgraded idler and starter gear too...It turns over with convincing verve...just wont fire. Cold starts are a frantic kicking 'til she goes. All starts when warm are a painless and trouble free, kick & go ! Still wont go off the button however....She has plenty of battery juice. As far as Im aware, I kept the compression and power valve dimensions to manual specs when she was bolted together again....Powervalve spring went from green to yellow during the rebuild.....
Any of you learned gentlemen care to posit their theory as to the root cause of the engine's reluctance to fire with a starter motor...?

Grtzzz....
Tim R

Too much compression with rebuilt engine? Starter nearly rooted? Too lean?

What pilot and needle clip position? What altitude? Sounds like its lean if it fires up easily when warm but not when cold. Does it require choke to start?

look at the carb, idle circuit for dirt in jet.

if carb all clean and still wont fire up better

look a reeds, if reeds are stuffed will be oil in airfliter box behind carb a very small amount normal tho.

My KTM300 won't start off the button unless I briefly tap the kill button while it's cranking. Try that. I've checked everything and can't find the cause. But try it out.