Use your thumbs like everyone else. LOL
Sorry for being so long-winded on this 70cc piston and ring subject. It seems to have come up periodically over the years with a little more clarity each time, but still lacking an explanation for the elusive thick ring 85239 references in the publications, along with being a little confusing when it came to the ring types and their applications in general. Mark and Steve (yes, my little buddy from Opie) had it pretty well covered back a few years with others contributing along the way, but McCulloch didn't make things any easier to nail down by the info published (or omitted) in their reference material and nothing has ever really been consolidated for easy reference to date.
Anyway, after reading just about everything ever posted on the subject and mulling over every chart and associated IPL I have, not to mention contributions and input from others, I'm relatively confident about posting the following as a convenient and accurate all-in-one reference for anyone who may find it useful. And credit where credit is due -- Steve provided the rough list back when I was in the process of rebuilding Kevin's 7-10 and beginning to research all this. Mark has provided info along the way as folks have inquired about the various pistons and rings. I've simply added and consolidated additional supporting info that I believe is correct up to this point in the conversation. The only thing I'm unsure of is the material of the thick 87166 and thin 89732 rings. I may have read Mark refer to them as steel somewhere along the line? Perhaps he'll chime in to clarify. One other dangling item is the two part numbers associated with the short connecting rod. The 83060 appears to only be associated with the 69030 piston even though all the other associated components are the same. Can't have that just hanging out there, now can we? Ha!
So here's what I've come up with. Any/all corrections or additional input to the following certainly welcomed and encouraged. It's a .jpg for easy download.
