If a broken ring.... this flathead motor (after inspection of both engine & diagrams on this site
) looks to be similar to a 2stroke engine top end rebuild... I used to be able to rebuild my cr250's in about 2-4 hrs (depending on beer) & have read that milling the head about 20-30 under while doing so is also cheap & easy to do...
Am I even close or is the job more involved than it looks...?