New piston rings

20774 said:

Likely your cylinders are stock and thus are iron lined, that is an iron liner that is shrunk to fit inside the aluminum housing. If I were replacing the rings, I would have the internal dimensions of the cylinder measured. You should have measurements taken near to the top of ring travel, mid travel, and near the bottom of the travel. You should also have those measurements taken 90 degrees to each other...so three measurements fore-aft and three measurements up-down. The purpose is to see how much the liner has worn and if it has worn in an oval fashion. There are specs for all this.

Maybe at 56K miles, you would still have in-spec liners. If not then, you would need to consider have the cylinders bored to the next size over. If you have them bored, you should provide the people doing the job the pistons and rings so they can ensure that the bore will be matched and correct.

Even if you decide to bore or not, I think you still need to hone the liners. Honing helps break the glaze and puts cross-hatching into the surface. This helps with ring break-in. You will need to establish your plan for break-in to ensure the rings wear in to get the best seal.

Snowbum discusses piston rings and cross hatching about 1/3 down this page:

https://bmwmotorcycletech.info/pistons.htm

Click to expand...