First off, if the oil is dripping from between the exhaust and the barrel you either need new exhaust gaskets or reseal them. This doesn't have anything to do with the oil pump.

If you do want to adjust the oil pump its adjusted at the pump end using the cable adjuster.

Oil wise, I would rather walk than use cheap 2 stoke oil. Buy the exspensive stuff.
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If I have to take the carbs off once more...