with doing timing I don't know the exact degree I am at. I can only go off of a notch in my ballancer witch I assume is TDC 0*.Typical symptom of using either an open element air cleaner or having an inoperative heated air stove/tube/flapper. Colder air is denser than warm air. Denser air with the same amount of fuel ends up lean. Lean mixtures take longer to burn so when the intake valve opens and before the exhaust valve is fully closed, combustion is still going on in the exhaust port and "pop". You could try a bit more accelerator pump "squirt" and/or advancing the timing a couple degrees.