Cylinder 3 and 4 arent getting hot

After much reading and trying to figure things out, I have established with a squirt bottle full of water that #3 and #4 are not getting anywhere near the same exhaust temp. after running the bike for a few minutes, i can spray 1 and 2 with water and it is gone almost instantly. when i spray 3 and 4 the water sits for a while. i have also noticed that the plugs in 1 and 2 are staying good while 3 and 4 are fouling (black and carbon on them) rather quickly. the carbs were rebuilt not long ago, and bench synced. i know they should be done with a manometer, but i was told syncing would only better up a good running bike. if anyone has any idea why 3 and 4 are not working right i would appreciate your help.

your not getting enough fire is what it sounds like
1st i would change plugs they could be fouled and wires could be a reason for loss of fire
2nd check pick-ups for corrosion or build up
good luck

just read the service manual. im really new to working on bikes and i cant figure out where the pickups or the electronic control is