New exhaust, now bike smokes. Why?

If I get this right
The problem came after the exhaust change.
15 minutes perhaps is not enough ..of course depending on how severe it is
I would try to reinstall the old exhaust back see if it stops.
If it is something like that
https://www.ebay.com/itm/Mac-Reverse-Cone-Exhaust-System-MAC-TT-Y650B-/193620446392

Those are shorter and have larger diameter on headers .
I have read about pressure waves in exhaust systems a system that now is altered
length and diameter .. With a rich mixture that might work before
Can be more off now
Pressure waves bouncing back interfering with combustion.
I would consider some carburetor cleaning additive in the gas since there was a known problem.
I would do the test without air filters ..getting a leaner mixture see if it helps. Short test only .
Did it shoot in the exhaust before ( Rich with a Leak )
Does it shoot now ?
Has it been sitting a while over the winter ?

5twins said:

Your jetting seems good for that carb set and the mods you have. I have similar mods and set up a carb set like that exactly the same. Question - what did you oil the pods with? If you used the special foam filter oil, that can be too thick and clog them. It's recommended to use just a 50-50 mix of gas and motor oil.

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Special pod oil indeed. I think I remember seeing a carb thread with your specs in it. Its good to hear mine match yours.