Once again, Doc is right with what to do. However, that is not what I would do since I am cheap and I like to make things work.
To me, there are 3 potential problems;
1. the bore is glazed over and the rings are fine but not sealing well. Deglazing the cylinder and making sure the rings move freely in the groves might bring back the compression.
2. The rings are worn and fit too loose on the piston, don't have enough tension left to make a good seal and/or the ring gap is way to big. Honing the cylinder and replacing the rings might bring back the compression.
3. The cylinder is worn beyond the point that even new rings will seal so the cylinder needs to be bored and a new oversize piston and rings fitted. There are some that believe it is OK to only bore 1 cylinder of a twin but that has never sat well with me.
If it were me, I would go with option 2 but use the next oversize rings so I can set the ring gap to the tight side of specs to kinds cover any wear in the cylinder. It may or may not work and might be a temporary repair, but given how easy it is to pull one cylinder on an Airhead, that is what I'd do.
To me, there are 3 potential problems;
1. the bore is glazed over and the rings are fine but not sealing well. Deglazing the cylinder and making sure the rings move freely in the groves might bring back the compression.
2. The rings are worn and fit too loose on the piston, don't have enough tension left to make a good seal and/or the ring gap is way to big. Honing the cylinder and replacing the rings might bring back the compression.
3. The cylinder is worn beyond the point that even new rings will seal so the cylinder needs to be bored and a new oversize piston and rings fitted. There are some that believe it is OK to only bore 1 cylinder of a twin but that has never sat well with me.
If it were me, I would go with option 2 but use the next oversize rings so I can set the ring gap to the tight side of specs to kinds cover any wear in the cylinder. It may or may not work and might be a temporary repair, but given how easy it is to pull one cylinder on an Airhead, that is what I'd do.