ORIGINAL: jedijody
SPS, ''shiny piston syndrome'' as coined by the venerable Ralph Cunningham, refers to piston skirt wear in new engines from clearances that are a tad too tight at the bottom of the cylinder. Other than added friction from taking a while to make it's own clearance it doesn't seem to hurt anything that I have seen yet. This is the reason some of them have benefited from a longer run it before expecting them to ''be all they can be''
Hey Jody and RTK......nice photos Jody , I have a quick question does this SPS only occur at the Jug Tabs or is that just coincidence in the photo........ The piston skirt shows a lot of pinch at the vary bottom of the piston(you can see in your first photo) the impression at the bottom of the piston skirt is the same width and height of the jug tab. The SPS above that area looks like (particle drag) as the piston drags metal fragments up the liner it could form this unsual SPS cone shape, that is much higher on the piston than an actual squeeze point.
It does makes since to me low idle could become a problem depending on how much friction squeeze a particular engine has. The reason I ask is if its just the tabs making the contact on the piston, it would be a much easier to fix than an out of round cylinder bore. A bore thats to tight will extend the breakin for sure.
Normally I don't like to ask question on an engine I don't own...........I only have the DLE55 from Valley View, but I am looking at the DLE30 for a 25% Edge 540 that I now have a OS 160 on.
Just a thought