How risk-friendly are you? The interference-fit appears to be insufficient - my guess is due to operator error or cheating. Your barrel appears to be a cast iron one. Recommended interference is 0.0025" according to L.A. Sleeve. Your engine runs under high thermal loads, and increasing the interference fit to 0.0035" may be advisable. Some air-cooled engines will require an interference of up to 0.0080", presumably when using alloy barrels.
Have the liner carefully removed without increasing the barrel bore. Do a calibration of the barrel bore using a bore thrust plate. Prepare a new slightly oversized lipped liner of good quality.
Install heavily shrunk liner by way of cryogenic cooling and by heating the barrel to 220 'C. Install liner under compression.
-Knut
Nice idea, but not in rural France, they don't do that stuff to tractors, they use government subsidies and get a new one!
In truth, it is a rule of diminishing returns. A new set of iron barrels is £600, plus shipping and import to France. And it looks like we will soon have several choices for alloy barrels.
This set of barrels cost me £50 and the liners around £60, plus maybe £150 for fitting and honing to suit pistons. The work was done through Norman White, using I understood RGM liners, by the machine shop he uses and trusts, it wasn't their first attempt at liners. (Norman has responded to me privately, but he has been playing at Donington this weekend. The inevitable request is can I get them to him, well today 'Covid Rules', no.)
I have no sentimental attachment, it was simply an attempt at having a spare set economically. The money was spent years ago.
If I can get them to Norman some time I will let him see what can be done.
I am planning to install a Maney set I bought from Yves ex Big Spender, and if that doesn't work I go back to the set I used in the first place and are sitting on the shelf awaiting next move.