Chainsaw Repair

Might be able to help you out. Most likely your 281's thin rings are the same as the 181's, so that being the case, try contacting Otto engine works at 410/398-7340.  Back a few years ago, one of my buddys needed rings for his 181.  They make custom chainsaw rings at very reasonable prices, hopefully they still do.   If they do it would be cheaper than buying a new aftermarket piston/ring.  That OEM cyl. would be more desirable to use than any aftermarket.   I have a 1983 181(never been rebuilt), of my dads that is totally stock with the thin rings, and its a prue torquey beast & still has 185 lbs. compression!  Has cut a lot of wood.  Good luck, and let us know of your results.   Happy cutting.