I gotta figure a way to post pics, my 25cc is even ground down the same!, cut the rear shaft as well, don't have a prop adapter or ign. kit, it does have a single ring. looks like an identical twin to yours, paid $10 for it as a weedie, ran great but its too small for my current project as well. I do believe mine has the M8-1.25 pitch. Also now that I'm holding it in my hand there is no lugs on the front fins, also my shaft is shorter. It must be almost the same but there is some differences, have you flown that engine or got specs on it?