the side with the lower temp likely has a plugged pilot circuit.
A test when warm and running ....progressively seating a given pilot adjust screw, bit by bit, should at some point cause that cylinder to misfire...backing out it should then recover. This should be the case on each side....if not, you've found an obvious symptom. Next > dig in to find the underlying cause. Throttle plates badly out of sych? Pilot circuit clogging to some degree? Tight, out of spec valves or a even spark issue?
If bike has sat inop for an extended period, likely pilot circuit. ...you are the Doctor...go git 'em.
Snow....brrrr. Around 50/sunny here today...batteries returned to 2 of my 4. I'm poised and can't wait to practice my own version of "social isolation"