I have a mild built banshee. Build consists of dune ported cylinders, FMF fattys, cool head 135 psi v force 4 reeds 30mm oko carbs with fuel inlet enlarged, uni filters. Ran great all spring and summer. Drove 600 miles to silver lake and ran it for and hour running normally and all of a sudden it's popping and acting stupid rich. Altitude was within a few hundred feet, temp was the same as when I jetted back home. I did plug chops until the plug looked what I thought was good in the spring. Now it won't run clean enough to do a chop. Fouls borh plugs rich in seconds. I am very hesitant to jet down, because if whatever phenomenon caused it to go rich goes away, then it will probably burn up.
I've replaced the coils and wires thinking they may have gotten weak with no change. I am going to try the stock carbs if I don't get any other suggestions.