Is there fuel to be burned? Reserve maybe?
The basics are fuel, spark, and compression.
So turning petcock off and looking in each float bowl one at a time would let us see if all 4 have an equal volume of fuel. Early in my own process of waking my bike up I did that and found one bowl empty. Gelled fuel had stuck the float needle into the seat so no fuel flowed. Also look in the bottoms of the float bowls for any loose "stuff", dirt, rust, etc.
Recently my bike started running like crap while going down the road. This same visual inspection revealed that a Pilot jet I had not properly tightened vibrated loose and fell out to the bottom of the float bowl.
Any trash in the system can block the petcock strainer, and if no strainer is present trash can block jets, especially the pilot jets.
I struggled with issues layered upon issues with my bike, as each was untangled it ran better. One issue that really drove me nuts was one spark plug gap was too tight, like almost totally closed. My fault, I think I must have dropped that plug and did not inspect it well enough to see the issue.
Bill