Hello Tenere Tom
You describing my Xt Tenere 34L exactly .
After 4500 rpm there is just not much happening. I went through the carbs endlessly,finally fabricated a small fuel tank,took the boots off and ran her like that to physically see with a torch what the sec carb is doing. Everything works fine there in both carb throats. Sec carb opening nicely with a healthy petrol mist sucked up by the venturi action.
Finally I have measured the ohm values of the magneto and pick up coils. they were way off their values. I can see sombody has done some shitty rewiring job in there with one of the lobes with no windings on it. This was all a couple of months ago so I have forgotten the values that they should be and what they was. I havent been able to find somebody in South africa that can rewire them for me.
I am sure there must be somebody just haven't found them yet as I am living in a small town in the bundu. I feel confident that this has got something to do with my lack of power (timing not being electronically advanced as there is no high rpm power or corect voltage. Hope my CDi is not damaged by all this.
Have you found the problem with your bike yet?
My bike starts and run okay,uses very little oil and very reliable but slow like a tractor lots of torque but no go :-) I am riding my other bike as finances are too low to spend on the XT now.

subie (south africa.)