15 rpm`s equal one reciprocation of the plunger, the travel is 1/4", now you need to calculate the volume of the cut away on the pump, I can`t remember exactly , but it was all covered in MPH back in the 80`s/90`s. I seem to remember about 35 mins to circulate the oil tank at 30 MPH. Remember a Comet will deliver more than a twin for the same MPH, because of the faster RPM. I`ll
see if I can find my original figures.