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BSA was out of business in 1972 before oil specifications required the use of anti-friction additives. It is these modern oils that make piston ring break-in an issue.

Modern engines use rings that are machined so they do not require the same break-in period as the old grey cast-iron rings need. They are perfectly round out of the box. Not so for iron rings, especially if they are coated. Also the cylinder they are fit to is prepared to a standard not achievable using the ORIGINAL CASTING DESIGN and finished to a tolerance nearly impossible to achieve with typical honing techiques (because of the material used and the design).

The tolerances expected for modern engines (held to a couple of tenths of a thousanth to accomadate coated steel rings) is rarely attainable with a 50 year old casting design. Take almost any British motorcycle cylinder made in the day with a heavy base, that is very thin just about the base, and with varying fin area from the bottom to the top that is used with air cooling. Modern cylinders are design to be perfectly round when in place and to be perfeclty round when they reach operating temperature. A lot of them are machined at the expected operating temperature.

Then you should measure the bore after it is offered to the crankcase and head torqued in place. Heat it up to 200 plus degrees and take you measurements again.

Even if you were able to take the cylinder from the hone, and you were able to get the bore straight and round to .0002" overall, you are not done. Just let the casting sit on the bench for a couple of days and measure it again. I am never surprised when I do this and don't have the same tolerance I had when I put it aside to rest. Any stress in the casting is reflected in how much the dimensions change. Sure we are measuring a few tenths, but modern rings can tolerate only a couple. That is one reason grey cast iron rings, and 150 grit finish was used in the first place, so the in the break-in period the two surfaces would "mate" to each other. Modern casting design software allows engineers to predict how the casting will react to machining and the heat expected when in use. Some cylinder preparation is done at temperatures expected

Break-in oils have no modern anti-friction additives (be aware that some don't have any anti-oxidents either). Some ring manufacturers offer an abrasive powder to coat the rings. You could do what Volvo recommended was to use a DRIER assemby technique (cylinder bore coated with oil using a lint free cloth, a light coating of oil on the thrust surfaces of the piston (and wrist pin bushing) and the rings left dry. When done the this way the cylinder bore will have just a little less oil on it as you would find as when you took the top end of to begin with. The key is: Drier than when we soaked everything with oil that had no energy saving additives. Or those who had a DA hair cut could take their oil soaked hands and smooth back their hair.

I've always used some really cheap, non-detergent oil to wipe on the inside of the cylinders after washing. Put some on the piston skirts, but none on the rings.

Mr Healy; yes the clip is from 1958.
By your comment about new engines, seems that will be more problematic than these old iron, in the near future for the owners when needed to take the cylinders etc to a machinist. I mean; impossible to obtain such precision...almost all these bikes, that cannot afford to send the motors to an specified machining shop would be in worst condition to ride with no problems than these old Triumph..

Also; in F&G page; and He built good Triumph engines; mention these about the new Hepolite rings etc
"We believe a 220 grit finish will work for this ring set,"
"We prefer to lightly lubricate the rings and ring lands with non detergent 30w oil and lightly coat the cylinder bore so it won’t rust. "
"Oil on the rings will not harm ring seating, as internet folklore suggests."

I am not saying that drier assembly is not good but I still never saw some one doing it and no any of these bikes smokes...

I thought I said that. The point is that new oils are too good, won't allow the rings to seat properly.

Some running in oil liberally applied to the pistons skirt should be sufficient. For the amount that you would be putting on and the fact the oil should be changed after first couple of hundred miles on a fresh bore, then it should be fine.

If anyone is interested, I have a large jar of arp lub that I will never use up. I could divide it into smaller bottles for the cost of shipping.