if i remeber corectly the choke just adds more fuel not take air away thus making the mixture richer and if it done the same thing with the stock jet in it than it may have been to lean from the way i read your post it looked like u made a pretty big jump in piolet jet size go back and start over with the next size up from stock and if it has the same problem try the choke thing again and see if it makes it worse or better if u pull the choke and it runs better its lean if its worse or no change its already too rich check your air screw also it should be 1 1/2 to 2 turns out the best thing to do is start with what your exhaust manufacurer recomends and start there check for air leaks everywere with carb cleaner and u may want to check the reeds also they may be jacked up some way im not sure but it definetly sounds like a fuel problem u may have to do the plug chop like someone already sugested also
