Dieseling Type IV

She likes to run. As a matter of fact, she likes to run so much that she tries to run, on occasion after the ignition is off. What could be the cause of dieseling in a TIV?

Retard the timing a little or run higher octane fuel. (Or both) Do something about it quick "spark knock" or dieseling will hurt your motor.

Im guessing its all from that carb you have on there..Single carbs dont really work well with the type IV - switch it back to fuel injection or get some dual carbs...
You might try adjusting your idle speed first - idling high can cause dieseling.

also check your plugs-if they are oily you may have some carbon buildup which is burning after you cut off the engine.