During tear down of an S&S 113" EVO the cylinders were found to have a strange wear pattern.
Both cylinders show the same pattern and they are worn in vertical stripes all along the stroke. It is more of a pattern than actual wear, everything is smooth when running a finger across the stripes.
What is the reason for this strange appearance?
Engine is opened because of oil leakage between the case halves but otherwise has been running very well. It was modified with the "SSW+"-type breathing but was modified back to conventional breathing + S&S reed breather as oil consumption increased with the "SSW+"-venting.