2002 Ski-Doo Shop Manual Volume One, Page 122Get this manual
Section 04 ENGINE Subsection 03 (443 AND 503 ENGINE TYPES)
Install proper ring compressor on piston assemblyENGINE TYPE 443 503 RING COMPRESSOR PN 420 876 090 420 876 970
NOTE: The ring compressor will not fit on over size pistonsCheck flatness of intake sockets no6Refer to ENGINE DIMENSION MEASUREMENT and look for Checking Surface FlatnessAt cylinder no4 andor cylinder head no3 installation, use aligning tool or exhaust manifold itself to ensure sealing of intake manifold and exhaust before tightening cylinder head nutsENGINE TYPE 443 and 503 ALIGNING TOOL PN 420 876 171