Engine or Carb issues - I'm at a loss

Hey guys. I'm back for some more help and suggestions. I purchased a 1982 750 Spectre a few weeks ago with around 20k miles on it (First bike and wanted one to work on for the experience :pinch: ).

So I've cleaned the carbs, installed a new starter, flushed the lines, replaced vacuum hoses, cleaned out the tank, new spark plugs, checked compression on all cylinders, verified the spark and checked the timing.

Now for the issue.

Only one cylinder is firing (#3). Sometimes #1 and #2 will fire but #4 never fires. #4 spark plug has gasoline on it so I know it is getting gas. It is sparking but it's hard to see in the garage during the day which makes me think it has a weak spark. I have traced the wires from both of the distributors and the right distributor (Right side while sitting on the bike) is going to #1 and #4 while the left one is #2 and #3. Sometimes it will idle without choke but it runs best with choke on. This makes me think some of the pilot jets could still be plugged but that's a different issue all together (I think). All cylinders have compression around 120 so at least that appears good. The oil is thin and smells like gas but I'm sure that's due to #4 not firing. Also, the bike gets finicky and it seems like it runs better when the petcock is set to Prime.

Sorry this has been long winded but I figured the more information the better

My question is 1) Do you all think the main culprit is bad distributor(s) or could it be that it is getting so flooded it is drowning the spark out?

One thing I haven't done yet and will do ASAP is put a voltmeter to the caps and check the ohms but I wanted to try to get a headstart and see what y'all thought about the issue and some suggestions.

I'm open to any and all suggestions and let me know if i left out any vital information.

Thanks for all of the help again guys. I really do appreciate it!

you need to do a clear tube test (fuel level)on carbs
and then go from there

is the timing advancer all rusted?

Hey P21. The timing advancer had some rust on it but didn't look to terrible.

I'll check the fuel level on the carbs.

If you can't tell, I dove in head first on this motorcycle with no previous motorcycle experience

hey my timing advancer had this like pinkish clay lookin stuff on it... like maybe some type of contact stuff to put on but not sure...also when i turned the unit to make contact it was real slow getting back to position..all i did was play with it a few times and it goes back nice and crisp. any idea what that could have been and if it was bad for the bike?

whats goin on with your bike koala? u clean ur advancer and stuff?

Hey guys! Got her running. Soaked the carbs in kerosine for two days and did another thorough cleaning. Also removed the rust from the gas tank using The Works toilet bowl cleaner (it did a great job!). Installed a fuel filter and adjusted the idle screw and fuel screws. I need to sync the carbs again and add new crush washers for the exhaust since ive got a bad exhaust leak which is really hurting my low end power but I've put 50 miles on her and haven't had any major issues. Thanks for all of the help guys! I'm also going to install a manual can chain tensioner.

thought it was left coil to 1 and 4 and right coil to 2 and 3?