First off Bro, You done an awfull lot of work and put a lot of money into this, AND YOU DONT WANT TO SQUANDER THAT! it would appear that you have "adjusted everything all at once" and dont know where to turn or what to try next! THE SINGLE most important thing is to find out IMMEDIATELY if the "BANGING" or "KNOCKING" is mechanical in its origin or not.
This MUST be the FIRST thing you ascertain, or all your hard work could go down the pan!
Put the bike on its main stand, dont turn on the fuel,dont turn on the ignition.
turn the engine over SLOWLY, A LITTLE AT A TIME by hand, either on the kickstart or in fourth or fifth gear by turning the rear wheel....( if you cannot manage this, get a mate to help and be QUIET, while you LISTEN carefully for any untoward mechanical noises OR indeed, any signs of the motor being not free in ANY way....If there is any "knocks" or "Bumps" like say the noise of a valve hitting the top of a piston or the like, THEN STOP IMMEDIATELY..
IF you can find, borrow, beg or steal get a doctors stethascope, and use that to listen, if not then a screwdriver pressed blunt end into your ear and sharp end on the engine does work to let you "listen in" so to speak.................
If all is not well and there are "untoward noises " happening, coupled with any jamming of the motor ar the like, You WILL have to pull it again unfortunately...(or risk damage!)
But, if all seems well, and it is JUST detonation in the "wrong place at the wrong time" so to speak, Then the usual rules will apply of Point gap,timing, valve gap, valve timing, and carb set up and sync. Logic dictates that if you have compression, and the correct fuel air mixture, and a spark thats good enough in the right place at the right time ergo it WILL run right! BUT, DO ONE THING AT ONCE, AND DOUBLE CHECK BEFORE moving on to the next....FOR example,you dont mention checking the condensors, and that should have been one of the first things that you did, replaced them!
I do not believe in bench synching the carbs, every motor is different and sucks differently, in fact EVERY cylinder sucks differently, and the only way to truly set the carbs is with a set of vacumn gauges or the like..ON THE BIKE!.......but thats for later.........start at the begining, the point gaps and condensors and ignition timing......There should be no REASON why you cannot set the timing correctly, if you cannot, then invest in a new set of points (or two!) and check that the points cam is not worn, if you cannot set them up right, then stop right then and there, untill you have solved THAT issue BEFORE moving on to the next! Have you taken each plug out and to see if they are (a.) the correct ones, and (b.) that they ARE ALL sparking correctly? That Should have been your first check! Only when you have checked the ignition circuits do you move on to the carbs....usually. (unless you know where the problem Is!)
Anyways, check the above out, and if you still have no joy, get back to me and i will go through the rest with you..no probs, Dont worry or panic just yet! JUst make sure you do each test slowly, carefully and double check, and then its easier for us to help you successfully. keep calm!
