Here is my take.
The sbn is usually ran on multi-cylinder/multi carb engines with a single carb having the pump capabilities. So if you are using a carb with the built in pump, should have capacity to supply plenty of fuel by itself. An extra pump may even be a flow restriction.
A 2 stroke will generally produce a pretty smooth one way flow, unlike a 4 stroke, which can produce reversing flow thru parts of the power curve, caused by the pipe and the valve overlap. Some carbs still meter fuel, regardless of airflow direction, so may change amount of fuel per air volume based on how much reversion you are getting.
A 2 stroke also draws air/fuel on every revolution at , usually about twice the revolutions per minute. So, times 4 may be a better comparison.
I would start, as stated above by dropping popoff to the 15-20 range. then use a tuning guide to get as good as possible.
Does your dyno have a/f testing capabilities?