Out of curiosity what are you using for a fuel pump? The factory pump puts out too much pressure for the Weber and will over power the float creating a rich mixture that could result in dieseling when you shut the ignition off. If you're using the factory stock mechanical pump that the Mikuni used you need a fuel pressure regulator that will reduce your fuel pressure down to 3 psi. The pump runs at 8 psi I believe. That being said,you also need to connect the fuel return from the pump to the fuel return line to the fuel tank or the pump will not last long. I have the same Weber on my '88 and have no dieseling issues.