Friend of mine had a jawa back in the 80s Brand New. We was teenagers then. I had a Vespa Grand did 25-28 mph. He took pipe off jawa it was loud as hell but we didn't Care time's were different obviously. We knew nothing about upgrades. But that jawa would leave the Vespa easily I think it did 40 + never stressed about gas then but it was 70 cent's a gallon.