0207547 EVINRUDE OWNER'S MANUAL

Illustration 1 g00295713
Typical exampleNote: An arrow or "Front" which is marked on the piston crown must be toward the front of the engine. (1) Top piston ring Width of groove in piston for top ring ... 2.57 to 2.59 mm (0.101 to 0.102 inch) Thickness of top ring ... 2.48 to 2.49 mm (0.097 to 0.098 inch) Clearance between groove and top ring ... 0.08 to 0.11 mm (0.003 to 0.004 inch) Gap of top ring (early engines) ... 0.40 to 0.85 mm (0.016 to 0.033 inch) Gap of top ring (later engines) ... 0.28 to 0.63 mm (0.011 to 0.025 inch)Note: Install the word "Top" toward the top of the piston. New top rings have a red or a blue identification mark which must be on the left of the ring gap when the top ring is installed on an upright piston. (2) Intermediate ring Width of groove in piston for intermediate ring ... 2.55 to 2.57 mm (0.100 to 0.101 inch) Thickness of intermediate ring ... 2.48 to 2.49 mm (0.097 to 0.098 inch) Clearance between groove and intermediate ring ... 0.06 to 0.09 mm (0.002 to 0.003 inch) Gap of intermediate ring (early engines) ... 0.30 to 0.76 mm (0.012 to 0.030 inch) Gap of intermediate ring (later engines) ... 0.40 to 0.85 mm (0.016 to 0.033 inch)Note: Install the word "Top" toward the top of the piston. New intermediate rings have a green identification mark which must be on the left of the ring gap when the intermediate ring is installed on an upright piston. (3) Oil control ring Width of groove in piston for oil control ring ... 4.03 to 4.06 mm (0.1587 to 0.1598 inch) Thickness of oil control ring ... 3.98 to 3.99 mm (0.1566 to 0.1571 inch) Clearance between groove and oil control ring ... 0.04 to 0.08 mm (0.002 to 0.003 inch) Gap of oil control ring ... 0.38 to 0.84 mm (0.015 to 0.033 inch)Note: A latch pin is used in order to hold both ends of the spring of the oil control ring in position. The ends of the spring of the oil control ring must be 180 degrees opposite the end gap of the oil control ring.Diameter of new piston pin ... 34.920 to 34.925 mm (1.3748 to 1.3750 inch)Diameter of bore for piston pin ... 34.928 to 34.934 mm (1.3751 to 1.3754 inch)Turbocharged Engines
Illustration 2 g00295713
Typical exampleNote: An arrow or "Front" which is marked on the piston crown must be toward the front of the engine. (1) Top piston ring Shape of groove in piston for top ring ... Tapered Shape of top ring ... Wedge Gap of top ring ... 0.35 to 0.80 mm (0.014 to 0.031 inch) Gap of top ring with internal step ... 0.35 to 0.70 mm (0.014 to 0.028 inch)Note: Install the word "Top" toward the top of the piston. New top rings have a red or a blue identification mark which must be on the left of the ring gap when the top ring is installed on an upright piston. (2) Intermediate ring Width of groove in piston for intermediate ring ... 2.56 to 2.58 mm (0.1008 to 0.1016 inch) Thickness of intermediate ring ... 2.48 to 2.49 mm (0.097 to 0.098 inch) Clearance between groove and intermediate ring ... 0.07 to 0.11 mm (0.003 to 0.004 inch) Gap of intermediate ring ... 0.30 to 0.76 mm (0.012 to 0.030 inch) Gap of intermediate ring with outside step ... 0.40 to 0.85 mm (0.016 to 0.033 inch)Note: Install the word "Top" toward the top of the piston. New intermediate rings have a green identification mark which must be on the left of the ring gap when the intermediate ring is installed on an upright piston. (3) Oil control ring Width of groove in piston for oil control ring ... 4.04 to 4.06 mm (0.1591 to 0.1598 inch) Thickness of oil control ring ... 3.98 to 3.99 mm (0.156 to 0.157 inch) Clearance between groove and oil control ring ... 0.05 to 0.08 mm (0.002 to 0.003 inch) Gap of oil control ring ... 0.38 to 0.84 mm (0.015 to 0.033 inch)Note: A latch pin is used in order to hold both ends of the spring of the oil control ring in position. The ends of the spring of the oil control ring must be 180 degrees opposite the end gap of the oil control ring.Diameter of new piston pin ... 38.095 to 38.100 mm (1.4998 to 1.5000 inch)Diameter of bore for piston pin ... 38.103 to 38.109 mm (1.5000 to 1.5004 inch)Piston Height
The piston height above the top face of the cylinder block is controlled by different grades of height of the piston. Identification of the height grade is by the letter that is stamped on the top of each piston. The height grade can be checked by measuring from the center of the piston pin to the top of the piston. The difference between each grade of height is 0.045 mm (0.0018 inch). Table 1 provides the specifications for the grade of height.
Table 1
Height Grades for the Piston    
Letter on top of Piston     Height Dimension     Latest Equivalent Grade    
A (1)    
70.334 mm (2.7690 inch)     G    
B (1)    
70.289 mm (2.7673 inch)     H    
C (1)    
70.244 mm (2.7655 inch)     J    
D (1)    
70.199 mm (2.7637 inch)     K    
E (1)    
70.154 mm (2.7620 inch)     L    
F    
70.391 mm (2.7713 inch)     -    
G    
70.345 mm (2.7695 inch)     -    
H    
70.299 mm (2.7677 inch)     -    
J    
70.253 mm (2.7659 inch)     -    
K    
70.207 mm (2.7640 inch)     -    
L    
70.161 mm (2.7622 inch)     -    
( 1 ) Earlier engines
Illustration 3 g00891532
Piston height above top face of cylinder block Quadram pistons ... 0.14 to 0.36 mm (0.005 to 0.014 inch)
Illustration 4 g00891548
Piston height above top face of cylinder block