Technical data and maintenance Piston
Piston
Unit: mm
Diameter of piston "a" (1) Class A - Blue 86.950 ÷ 86.960 Class B - Pink 86.960 ÷ 86.970 Class C - Green 86.970 ÷ 86.980 Class D - Yellow 86.980 ÷ 86.990 Class E - White 86.990 ÷ 87.000 Oversize 0.2 87.144 ÷ 87.160 Oversize 0.4 87.344 ÷ 87.360 Oversize 0.6 87.544 ÷ 87.560 Height of first seal ring seats "b" 1.535 ÷ 1.555 Height of second seal ring seats "c" 1.775 ÷ 1.795 Height of oil scraper ring seat "d" 3.015 ÷ 3.035 Diameter of gudgeon pin holes in pistons "e" 21.004 ÷ 21.008 Clearance between cylinders and pistons (not oversized) 004 ÷ 006 (1) To be measured perpendicular to the gudgeon pin hole at a distance of 13.9 mm from the gudgeon pin axis.
Piston rings
Unit: mm
Thickness of rings "a" First ring 1.478 ÷ 1.490 Second ring 1.728 ÷ 1.740 Oil scraper ring 2.978 ÷ 2.990 Ring gap "b" (1) First ring 0.30 ÷ 0.50 Second ring 0.30 ÷ 0.50 Oil scraper ring 0.25 ÷ 0.50 Axial play between piston rings and housings First ring 0.045 ÷ 0.077 Second ring 0.035 ÷ 0.067 Oil scraper ring 0.025 ÷ 0.057 (1) To be measured in the checking ring nut or in the cylinder.
Gudgeon pins
Unit: mm
Outside diameter of gudgeon pins"a" 20.996 ÷ 21.000 Clearance between gudgeon pin and seats on piston 0.004 ÷ 0.012
02 Maintenance
