It is a working engine, i think it has had a max of a gallon and a half into it, however it was in a truck a friend gave to me and they didnt put the piston at botom dead center or the aro. i have one that was cared for jsut like it and it really rips i took it apart to clean it because of the way they cared for it and i took it all apart and cleaned it. I was trying to get some pics of the piston and sleeve while i had it all apart so those of you who are interested could decide if u wanted it or not, i think its a fine engine. If you want i can try and get some better pics when its brighter so you can see how it looks, hope this helps. thanks for lookin