Honda 400EX problems

[Chevy305]

So my family has had this Honda 400EX sitting in our shed for a few years and I decided I wanted to see if it could still run. Long story short, I drain the old gas out, rebuild the carb and replace the battery. It runs but it wont idle well at all until it has ran for over 20mins. Does it really take that long for a small engine like this warm up. So I adjust the mixture and it seems to run best with the screw out about 4.5 turns, that seems excesive. Also what has me most concerned is that riding slowly through the woods I noticed the exhaust was glowing red hot. Any insight would be appriciated

 

[sweetk30]

tons of small atv carbs i have cleaned out over the years have the super tiny jets for low speed and idel cirkit pluged with sludge that brake clean or carb clean wont get ride of. so i use a cutting tourch head cleaner vary carfully to clean the hole out up the center.

and had some honda's have the oring go bad between the head and intake /carb boot. suck a lot of extra air.