Thats not really what they are designed to do. They are there to catch the fuel/air backwash when the piston goes down and to give an immediate supply before the carb can provide the fuel/air. They hook-up between the crank and carb, so they are independant of the carb's throttle position. In any case, I would imagine that they would be standard on all of the high-end engines if they made much difference, but I generally only see them on the thunder tiger low-end models.