So you mean, check the light when I put the ring in there to see if I can see daylight coming through the edge of the ringOne that fits the bore........we always ran o&h rings cast or gold and were available in 52.6, 52.7 etc. we used the one that fit, check with light and set .008-.010 end gap.
Like Sundog says: gap really doesn't matter much as long as there is "enough". Fit and tension matter though.
I have literally... at the track... lifted the cylinder off, pulled the ring off and ground the ring to open the gap to about .050". Zero difference in performance. Testing was done on a Yamaha, at Willow Springs in an enduro kart... kinda like driving a dyno because the track is pretty much flat out all the way around.
Id like to hear more about that.I tried something someone said on here before with a sudam and ended up with a quarter size hole in the piston.lol