ORIGINAL: BadClownCrawler

simple fix. no need to switch oil ratios. you said you run the needles as fat as you can. that is the problem, the needles are too fat and fouling out the plugs. lean up the low needle 1/12th a turn. bascially you getting too much fuel and its fouling out the plugs is all. lean the low up a bit, and likely the high a tad, and you shouldnt foul out as often.

the fuel moves to the carb via the diaphram in the carb itself. if the tank is not vented, then you will create a vacuum in the gas tank. that small hole that is made in the gas caps is what allows the tank to vent. Gassers are NOT nitors, and DO NOT work off Tank pressure. they have 2 lines going from the tank to the carb becuz when the diaphram is full of fuel, it has to have a place to push the excess fuel to. thus the gas flows thru the 2nd line (usually the yellow one) back into the gas tank.

and fwiw, some fouled plugs may live on, but often once its fouled out, its dead.