Stripped thread on cylinder exhaust stub

[Nodohc?]

Hi all , taking apart a gt250 I just bought , taking off the silencers , one was held on with exhaust putty no thread on the stub for the castellated nut to grip , is the cylinder scrap or is there a way to fix this?
Grateful for any advice

[badgereng]

Back in the early eighties, I ported and polished the barrels on my mates GT250…. If the grey matter library is still working, the barrels have a single threaded stub for the exhaust collars to screw onto. They are not like the twin threaded studs used on the GT380 / 550 which are easy to replace if stripped or sheared.

If the threads are completely gone, this will not be an easy or inexpensive fix.

I’d look for a used barrel as it may be cheaper than any possible fix on your threadless one.