You have an air leak somewhere in the Dio block the motor or carb... Could be crank seals also... Your throttle could be binding not closing all the way of your 100% it's sealed up everywhere... Try running it with the choke or choke it with something to get it to rev down... Are my thoughts on hi revving engine... Some of those have boost ports and that can do it also if it's not plugged or usedI'm sure it's not a air leak but I can't even check because I don't want my engine to blow when I pull the clutch at a stop any ideas how to get this to stop or a way to find what's wrong I have a zeda 80 with dio reed valve and a oko21pwk carb
Everything helpsNot sure if this helps but I had exact same problem and I eventually figured out that one of the screws that hold my float bowl chamber to the bottom of the carb was loose