Ok, so I’ve been riding my new Sun 24" Uni for about 4 months now, and I’ve noticed on the petal that I mostly put my weight on for idling and things has a strange roughness when I rotate it. And also, when I idle, that petal sometimes makes a popping noise. Is it just a problem with the bearing, or is it just the pedal that’s causing the problem?
pedals do that after a while 
you can try to tighten to pedal to get rid of the noise but if its a plastic pedal its mostly like that a bearing go put out of place.
Can you find a picture of the style of pedal you have? Your pedals might have ball bearings or they might have bushings.
If bearings, it’s likely the bearing has worn a bit so they could use some adjustment - A fixable problem. If bushings, they might be wearing so the surfaces no longer slide as they should - Problem should be ignored until failure or replaced.
Ok, Thanks for the info! I’ll try to get around to uploading some pics of my pedals and bearings.
If your pedals have gone bad, these are better than stock sun pedals, very popular and a real cheap upgrade.
http://www.unicycle.com/sale-items/odyssey-chameleon-twisted-pc-1.html