It is a fresh build. I ran it during g break in for 20-30min at 2500rpm
I then installed the inner valve springs and proceeded with carb and timing adjustments. This was the first time the engine saw 2500+ rpm. and this issue surfaced. Still today the engine starts easy, idles 1100 and reacts instantly to short burst of throttle. But when hitting the 3000+ rpm mark, the issue reappears.
