I have a Zenoah G45cc engine I haven't used for a few years. I had problems starting it so I put a new carburetor kit in it, and tried to hand start it to no avail. With the new kit installed, fuel began leaking from the two tiny holes(fuel pump)on the back of the cab. I was not successful stopping the leak, and the engine wouldn't start, so I purchased a new carburetor. After installing the new cab, I still was unable to hand start it so I used a drill with enough RPM's to turn the propeller and the engine started(after several tries)I let it run for awhile and noticed black oil coming from the exhaust. I shut it down and was unable to start it again. Could this mean that the bearings are bad?