ok iv got a 1984 honda 200s it had a oxidised carb the idel air screw hole was huge.. ok now i had a carb from a 1982 honda 185s that was good i swapped the low speed jet beacuse the 200 had a smaller jet35 i think or similar instance then the 185 had like 38..the manual said the same. the main jet on both was 100 .i installed it run really ruff i cked the valve lash it was like .008 ex and .012 in. so i fixed that with re ajustment of .002 then adjusted the cdi pick up to .014 .so i did all this still run like it was loaded all the time really rich black exahust so i droped the main jet needle to the top notch to lean it out its decent no black exahust but just not perfect enough for me yet......well the only thing i did not do was switch the main needle jet seat on top the imultion tube... other then this what could be wrong? is the carb body diffrent? lmk thanks guys

 

I had the same issue with my 185s Carb
Still have not figured out why but I put another carb from later 200s jetted problem gone
I have tried several times going back to stock 185s carb runs rich black smoke
Good luck
Ray