Temperature difference left to right cylinder

Hey everyone. Getting my 71 commando up to snuff (new tires, fluids, etc) and fired her up today for the first time. Started 3rd kick and idles strong. As it was sitting there idling I checked how the cylinders were warming up. Just after a few mins there was a noticeable difference in temperature left to right side. Left was getting up to the 180 range where the right side was still just over 100. Gave it some revs and let it idle again and checked. Same thing about a 50 degree difference left to right. Checked spark and it was good. Both plugs seem to have fuel on them. Compression test is next but it's running and idles like a rock. Could.it really be compression? Bike hasn't run in a very long time (years) that's why I'm doing the whole refresh. Could it be the carbs? Fuel was drained before storage so it should be ok. Idk..... When the temperature difference didn't change after about 10 mins I shut it off, never took it for a ride. Any advice would be awesome. Thanks again everyone!

If the plugs have fuel on them you are running too rich. Likely the cool side is not firing correctly or the carb balance is way out. Do a full tune up.

I presume are we talking Centigrade here? Where are you checking the temperatures?

Plugs are brand new. Has electronic ignition in it currently. I'm taking the temperature right at the header I front of the cylinder. Tried moving around, checking a few different places but all seems to say the same thing. Left cylinder is way hotter then the right. From my experience with other brand motorcycles the left cylinder seems to be fine it's the right side staying so cool that worries me

Take it for a run before doing anything, put a load on the motor and see how it goes, if its running good without any misfire, as well both carbs can be set/adjusted differently to each side even needle positioning can be set different to each other, have you pulled the carbs apart as be a wise thing to do if left sitting for a long time, as well there is a lot more weight hanging off the left side of the crank, as well not good letting them idle for too long, does more harm than riding them slowly to get up to working temp.

I agree in a perfect world I would pull the carbs off and go through but the previous owned installed different carbs that I still have yet to identify so be able to buy a rebuild kit. They are amal carbs but they are much larger then the factory ones. The owner before said it was a "kit" ( it does have different manifolds) he bought. Said something about later triumph carbs but again I'm not sure. I will eventually pull them off and go through them but I would love to ride this thing for the first time.