iv been looking for a carb rebuild kit for my 87 250x and i see tons of 91-92 carb kits on ebay but hardly none for the 87-88.... all i really need are the o rings and i already now where im getting them but i was just woundering whats the difference in the carbs?

 

The biggest differences in the two series is that the 91-92 models had a different pump diaphram and a slightly different float bowl shape near the pump. So the o-rings and gaskets you need on the lower side of the carb will likely not fit the 87-88 model carbs but I have never attempted the swap myself, so I have no idea.