2005 Ski-Doo RT Series Shop Manual, Page 75Get this manual
Section 02 ENGINE Subsection 07 (TOP END)
Scrape off carbon formation from cylinder block exhaust port, cylinder head and piston domeNOTE: The letters "A or B" (beside an arrow on the piston dome) must be visible after cleaningClean the piston ring groove with groove cleaner tool or with piece of broken ring
INSPECTION
NOTE: For dimension measurement procedures, refer to ENGINE MEASUREMENT