I hope this is a tale of woe, but a tick could mean you have been running on the lean side of optimum and detonating.
Detonation causes heat and can damage pistons and rings.
Compression test, leak test.
Pull the pipe off and look up the exhaust port for piston damage, I hope you prove me wrong and nothing is amiss.
After reading through the entire thread, I think Blaaster is right. This is a tale of woe. Sounds like you need to have the head measured and purchase the piston for the next size up in bore. Just knowing that the wall is scored would be enough for me to correct the issue.
I don't have calipersbut it's 30mm i.d. On the motor side. Doesn't that help at all?
Thanks!!!
DMC = #260 main jet.
Aftermarket air cleaner + 1 or 2 sizes larger.
Air box lid off +2
32:1 pre mix +1
DMC recommends that the needle be set at its richest setting (bottom clip)
Elevation and temperature also affect what jets you should use.
Plug chop to confirm.