Have a 5hp yard machine tiller put oil in where there was a white fill cap started tiler and it ran for a minute before putting out a big black smoke and quit running it ran fine before putting oil in thought it was low drained engine oil engine still hard to turn over what did I break ? Did not have a manual with the tiller bought it used thanks for any thoughts

Do you have a model number ?

You probably got oil in the head. Take out the plug. Spray carb cleaner into the head. Put a rag over the hole and pull starter. Do it until it's clear. Clean the plug with carb cleaner, but you might be better off replacing it.

Replace plug and go.

Hi,
Good chance someone could find you a manual if you provide numbers from the model tag; on that machine it could be on the frame around the engine or "hidden" inside and under the handle assemby.
Peace,
Clarke

Sure that was not the gas cap you put oil in