I tried to calculate by multiplying engine capacity (swept volume) by rpm, divided by 2 assuming it is a 4-stroke and arrive at cfs air.
However, there is no way the cylinder is filled with atmospheric pressure air at each stroke. No time for the air all to flow in.
The value, 1.7 cfs for a 60 HP engine gives crazy values for air velocity at the intake.

I also calculated on the basis of air needed for combustion of the known amount of fuel. That gives a value only 4% of the values based on swept volume.

Comments please