2017 Rps hawk 250 red hot header help

[Robertk]

I need help. I dont do much with the internet an took me an hour to figure out how to post on here............

But I have a 2017 hawk 250 with 190 miles on it.

I just installed..... mikuni vm26 with (120) jet, NGK iridum, full exhaust and did the air box mod.

When i start it up it only takes 20 seconds or so and the header gets CHERRY RED HOT. So i shut it off.

What is causing this?? I tried puting a 125 main jet in it and playing with the air/fuel screw, tried using the old spark plug, checked valve lash, ect ect....

Im afraid to run it long enough to get the air/fuel mix set so it will idle at lower rpms. (Pry 1500-200rpms now)

Is it super lean or does this exhaust pipe just get that hot cas its cheap and thin?
I dont want to drop a valve or anything