Should be noted, that I do NOT have a cylinder kit. The head, piston and rings are all stock. The new carb does NOT have air/fuel mixture adjustment. Only thing that can be changed is up jet/down jet. I did NOT advance or retard the timing. It seemed to be "four stroking" without the silencer on the exhaust. It seemed to stop "four stroking" once the silencer was put back on. I'll start tearing into her once I'm not mad anymore....lol.