1981 KZ440LTD Left carb giving me fits.

Ok, I have been through the carbs, and we have spark. The left cylinder is just not running. She is just running on the right cylinder. We also have this wonderful backfire out that left carb. Any ideas?

Insufficient intake valve clearance might be causing the backfire. Or possibly some damage to the valve or valve seat. Whatever would prevent the supposedly closed intake valve from being actually perfectly sealed when in its closed position.

Some of the combustion within the cylinder -- instead of being fully contained within the cylinder -- is probably getting through the imperfectly seated intake valve and going out backward through the intake port and carb.

Good Fortune!

Well Patton, I think your on to something there. I did try to loosen the intake valve some. I did get it to run better some. But then she went back to pissing me off. I think I may have a valve problem there. Once I get some of my other summer projects finished up here, i may pull the head off it.

You have the vacuum port open. Don't you see the flames coming out of it? That would cause a excessively lean condition on that cylinder.
Steve

I took the cap off because of that little flame. It would keep blowing it off....

Do a compression test.
Looks like a burnt or bent valve
A not proper valve to valve seat surface and a too tight valve clearance are the reasons why his happens.