Ok, not a motorcycle, but a 1990 1.25 evinrude 2 stroke outboard, I wanted this where engine knowledgeable people would see. I've rebuilt the carb a couple of times on this thing bought it new. I rebuilt it last spring, but I didn't replace the float or the pin, did replace the needle and spring, well the thing just pulses, the rpms go way down then come back up, does it at a pretty quick frequency, sometimes it will just start running right for a little while, I just ran it that way last summer, I use it on a canoe in the river, usually just for spots I want to skip going downstream.