Good progress. Don't be disappointed that you didn't entirely fix the problem - it is extremely rare that fouled plugs, once replaced, actually solve a problem. Fouled plugs are a symptom, not a cause.
So here's what we know:
Your plugs foul. There are five main reasons why that happens, in no particular order:
1. Your rings, valve guides or valve stem seals are worn. Not likely in this case - your plugs would be black and oily, unlike gas-fouled plugs, which are gray/black and fluffy.
2. Your timing is retarded - that is to say, your plugs fire later in the stroke than they ought to. There is an optimal point in the range at which they need to fire (not TDC, but just before it); this gives the gas enough time to combust and produce the resulting shock wave that will force the piston back down. If it fires too late, not all the fuel burns. What doesn't burn gets deposited on your plugs, piston and cylinder domes and the walls of your exhaust path. This is likely.
3. Your ignition is weak or intermittent. Points often get contaminated, resulting in failure to consistently connect electrically. Then, though the bike will run, it won't burn all the fuel - same effect as above. If you run the test from my previous post, you'll be able to tell us if your plugs spark consistently and what the spark looks like (i.e. fat blue spark, tiny orange spark, etc).
4. Your carbs are fouled. More specifically, deposits in the air channel of your mixture path have caused a shortage of available air through the idle circuit. You'll likely find you're also lean at full throttle for essentially the same reason - the same crap that's clogging your air paths through the idle circuit is also clogging the fuel through the main jet at throttle.
5. Your carbs are damaged or not set up properly. Damage isn't all that common unless someone's been mucking about with them (the exception being 350's with the rubber diaphragms that are notorious for failing). Bad setup, on the other hand, is extremely common.
Let's assume you have a combination of problems 2-5.
2. You can probably get back on the road without addressing your timing, but if your fear of points outweighs your interest in having a reliable bike, you bought the wrong machine. Sell it to someone cheap on caferacer and buy a bike with electronic ignition and fuel injection. While you're at it, go ahead and paint it pink and buy yourself some tassles. Let's come back to 2 in a minute.
3. See previous post.
4. Clean your carbs. I mean, REALLY clean them. The bit you need to pay the most attention to is the channel behind the mixture screw. Your manual will tell you which one that is. Stick the carb cleaner straw down the hole and spray the hell out of it. Carb cleaner will spray out of a hole in the float bowl. Plug it with your finger and keep spraying until carb cleaner pops out of another hole on the venturi wall. Worried about cancer? See above, re: pink bike w/ tassles. Remove and clean every jet and passage. Use an entire can of carb cleaner on the pair. Oh, and resist the temptation to stick a pin through brass jets.
5. Setup: write down the jet sizes while your carb's apart - we'll tell you if you've got the right ones in there. What's your elevation? Maybe your carbs are fine but your air's too thin and you need to jet down. When you put them back together, set the mixture screw 1.5 turns out, then follow the book directions to adjust it to get it perfectly dialed in - or check back here.
SO. Do 3 first, it takes five minutes and there's a lot that that rules out. Then 4-5, as that will probably get your bike running on both sides. Then do 2 so I won't make fun of you.
A
