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Engine Mechanical TopicsDiscussion for motor builds, cams, head work, stripped bolts and other engine related issues. The good and the bad. If it goes round and around or up and down, post it here.
Yeah, that's normal looking. The four spots you are referring to line up with the cylinder stud holes in the cylinder and the expansion and contraction rate is slightly different in those areas. That's a large bore size for an air cooled engine and it's a modern marvel of engineering and manufacturing that the cylinder bore stays as stable as it does during heat cycles.