Originally Posted by
mjraines1
I prep the cyl with 1000 grit paper, oiled everything, run two tankers of fuel very rich, leaned out some on no 3, run to peak on 4.
Paper is too fine. I'd guess the cylinder didn't get roughed up enough so the ring isn't wearing in. I would use a rougher grit and scuff the liner again, then re-run it. 4-stroke rich for a minute or so, then take it to the 2/4 break where it runs mostly in rich 2-stroke mode with occasional miss and do this for 4 tanks. On that 4th tank I run mine so it's -just- lean enough to run a full two-stroke. Run two ranks that way. Then peak it out and run 800-1,000rpm rich of peak for awhile. Maybe a dozen flights. ST rings are fairly hard and take a long time to seat. Expecting stellar compression and perfect ring seal after 4 tanks (unless they were 16oz tanks) is very optimistic IMO.