I had an 87 500 that I restored and had some issues with that carb. The carb is a Mikuni VM38. The info you got from the dealer is correct as far as the main and pilot jet. The problem I ran into was nobody knows anything about this carb, it appears to be a one off type carb made for Kawasaki. I contacted Mikuni and they were unable to help with this carb as far as jetting is concerned. Mikuni still makes a VM38 but the jet #'s don't match what's in the 87 model carb and Mikuni was unable to cross reference the jet #'. I was able to buy pilots and mains but the biggest issue was the needle jets are no longer available. The needle jet would let you tune the 1/4 throttle through 1/2 throttle settings. I was able to get the carb some what jetted o.k by playing with the main and pilot and pilot screw adjustment along with proper float height adjustments. Your best bet might be to find a ebay carb from the 89 or newer 500's, but you might need to get the throttle control and the throttle cable will be different.