You can see, pulse width for front and rear cylinder differs for up to 10% in length. 10% difference sounds less, but this means a pleanty of additional discharged fuel when injector time is prolonged in that manner, it is more than just a little. Furthermore it is curious, that the same cylinder is the lean one at low engine speed, to be the rich one at the end of the range and vice versa.
This sophisticated fuel map for partial load is the answer of the KTM engineering to the "herky jerky-problem" of the SD. This happens under "open loop". Said 2,2V or 30-35% throttle opening corresponded to a common "handful of gas" as used for "normal" acceleration. This range is not emission controlled so the O2 sensors are out of order..
This diagram shows further that cylinder selective fueling is no invention by the aftermarket but common praxis of the manufactures. And it is also evident that there must be a good reason for the KTM engineering to favourite such a fuelung for partial load.
And unfortunally it is also a matter of fact. that this fueling is no real solution for the problem.
In place of trying to improve this cylinder selective fueling by sophisticated cylinder selective exhaust gas analysis (BTW: I guess you are running into trouble when installing WB-probes into the stock plugs at the primary headers), I prefer a different approach: This extremely asymmetric fueling by KTM for front and rear cylinders reflects a proportional uneven cylinder filling of front and rear cylinder. This is the reason, why the engineers have chosen this fueling.
But the KTM-engine for itself is (almost) perfectly symmetrical for both cylinders regarding cam timing and combustion chamber lay out etc. . Also the length of intake runner at the engine inlet and the primary exhaust tubes at the outlet match nicely. Therefore the obviously uneven charging of front and rear cylinder, the stock KTM partial load fueling is reflecting, is caused by something:
The stock KTM-V2 airbox is the reason for this trouble. This airbox - as most air boxes do - acts as a two stage - resonator, wherein the box volume couples the resonances of two different sources to a new and "summary" wave action. One source is the intake snorkel feeding the air into the box:
................................
Why should the rear cylinder run hotter than the front one? This engine is liquid cooled with a prettty advanced cooling system using a powerful pump circulating the water real fast running a small delta-T for radiator inlet and outlet. So temperatures inside of the engine are well balanced.
I have spent hours into cylinder selective exhaust gas analysis. Adjusting the fuel supply perfectly helps, but uncovering the real causes for discrepancies is more effective.