I worked on my bike yesterday to try solve the problem the previous owner had with it of fouling plugs, I thoroughly cleaned the carby including removing a bunch of carbon from the carb slide and replaced the old coil with a brand new one as well as putting in an iridium plug and a brand new battery.  She roared to life after a few cranks (with the help of a few sprays of Aerostart) and I took her out.  She had a bit of a miss in her but this was expected as she hadnt been run for 3 years and it seemed to improve as the bike warmed up.  I parked it and put my cousin on for a ride and he went for a decent squirt.  By the time he came back it was singing.  The idle was up a bit when he returned so Ill drop that, and I had the carb breathing straight from the atmosphere so I could spray the Aerostart in there so Ill connect it up to the aribox before I start riding her properly.  

My ques is, when we parked it around the side of the house in the dark and killed all the lights I noticed that that header section of the pipe was glowing red.  Not bright red, but deep red and you could only just see it with the lights off.  Is this normal or is it likely that having it breath straight from atmosphere caused it to burn lean?  My cousin was up it when he was riding it though, blowing the weeds out of it, so this also may have contributed.

Its an 86 with a 155 main, not sure of the pilot.

Yea, that seems like a good guess.

You didn't mention if you have an aftermarket exhaust on the bike, a free flowing muffler along with no air filter will cause the bike to run a lot leaner, easy in/easy out makes the thumper scream and shout

Yeah I put the pipe back on that connects the carb to the airbox and its like a different bike.  Starts first crank, rides so much smoother and is quite simply better everywhere.  

Now I have to ride it for a week straight to see if the coil I replaced fixed the plug fouling issue.

cool beans !