Ybr 125 running issues

[Steve_ybr]

Hi guys new here i have introduced my self having a few annoying issues with my bike at the moment but will get to the main one first , having issues with my ybr  125 custom fuel injected brought it has a none runner got it running yesterday with a new battery ,  now a new problem as occured it will splutter to about 1-3k revs on the stand for about 3 seconds when cold  then it revs fine , soon as  the engine is hot it wont rev past 4k revs at all it will just sit there in any throttle possition miss firing and back firing , spitting till i lay off the throttle then goes back to idle , idles perfect , no smoke or noises from the engine , no fault codes on the dash , if i ride it it will barely move under load just keeps foing the above mentioned problem , i was thinking either wrong spark plug it has cr7hix (irridium ) it should have a cr6hix if i was to go irridium , or the coil is on its way out  i have stripped all the fuel injection system even swapped the bodies and cleaned it all everything is air tight and i belive the fuel pump is pretty new ( primes and pumps well )any input would be great thanks i will do a video tommorow to show whats going on thanks guys