Question on my 81 Maxim 550, it just wants to back fire..

Well it has always had the odd problem off not starting, I was thinking it was shit in the tank, it seemed to run bad or not at all when low on fuel, but I have since cleaned out the tank, the peacock works good so there is fuel.It all start about a week ago I went out and started it with the choke on but before it could warm up it started to lose power and the more I tried to keep it running the worse it got till it will only back fire now, it takes about 3 , four second attempts before it back fires, today I took the tank off again and made sure the peacock was giving fuel, there was one thing I found , but I would think it wouldnt stop it from start completely and that is one of the spark plug boots came off, I attemped to rewire it to the boot, this is one the left side outer spark plug. also the same side inner spark plug was carbined up more than the others.There has been times that this bike has started and not sounded right and I would just take it out and it straightened out on its only. Kruizin