I have a set of pd50s that are on my cb650, I had them off the fix a leaky accelerator pump. In that process they were invertered, on their back, on their face etc. I put them back on turned on the gas, fired up the bike, it ran, I shut it off, walked away, came back a minute later and gas was coming out the overflow. I tapped all the bowls with a screwdriver and actually heard the float drop. I guess they get bound in all the tumbling about. Give it a shot before you yell at your uncle.