This is just my theory but I think the 4-strokes deliver only half the amount of exhaust pressure pulses than that of 2-strokes but each one is much stronger than the 2-stroke. So because of the check valve, the average pressure in the tank will be higher on a 4-stroke (if they both use exhaust pressure).
ORIGINAL: BillS
hmmmm.... I always heard people surmise that 4 strokes developed LESS muffler pressure....
I have heard the same and will post the muffler pressure of a 91 Saito on Thursday. Must pick up a header that was broken.
Generally I am finding 45 size two strokes to develop from 12 t o17 column inches of water (about 1/2 to 3/4 psi) depending upon the muffler.
Bill