105672-0020 ZEXEL 9 420 615 507 BOSCH AUTOM. ADVANCE MECHANISM 9420615507 1056720020 16810z5561

Piston Group.(1) Crater. The piston is a symmetrical piston with an "on center" crater.Thoroughly lubricate piston group 360° in zone (A) with clean engine oil prior to inserting into the block group.(2) Top piston ring.Install ring with side marked "UP-1" toward top of piston (yellow color stripe to right of ring end gap). Clearance between ends of piston ring when installed in a cylinder liner with a bore size of 125.00 mm (4.9213 in) ... 0.625 0.125 mm (.0250 .0050 in)Increase in clearance between ends of piston ring for each 0.03 mm (.001 in) increase in cylinder liner bore size ... 0.09 mm (004 in)(3) Intermediate piston ring.Install ring with side marked "UP-2" toward top of piston (green color stripe to right of ring end gap).Width of groove in piston for intermediate ring (new) ... 3.061 0.013 mm (.1032 .0005 in)Depth of groove in piston for intermediate ring (new) ... 3.727 mm (.1467 in)Thickness of intermediate ring (new) ... 2.990 0.010 mm (.1177 .0004 in)Clearance between groove and intermediate ring (new) ... 0.048 to 0.094 mm (.0002 to .0037 in)Clearance between ends of piston ring when installed in a cylinder liner with a bore size of 125.000 mm (4.9213 in) ... 0.625 0.125 mm (.0250 .0050 in)Increase in clearance between ends of piston ring for each 0.03 mm (.001 in) increase in cylinder liner bore size ... 0.09 mm (.004 in)(4) Oil regulating piston ring.Oil ring spring ends to be assembled 180° from ring end gap (white colored portion of spring must be visible at ring end gap).Width of groove in piston for oil ring (new) ... 4.033 0.013 mm (.1588 .0005 in)Depth of groove in piston for oil ring (new) ... 3.727 mm (.1467 in)Thickness of oil ring (new) ... 3.987 0.013 mm (.1570 .0005 in)Clearance between groove and oil ring (new) ... 0.020 to 0.072 mm (.0008 to .0028 in)Clearance between ends of piston ring when installed in a cylinder liner with a bore size of 125.000 mm (4.9213 in) ... 0.55 0.15 mm (.022 .006 in)Increase in clearance between ends of piston ring for each 0.03 mm (.001 in) increase in cylinder liner bore size ... 0.09 mm (.004 in)After piston rings have been installed, rotate rings so the end gaps are 120° apart.(5) Crown assembly.(6) Piston pin bore diameter in piston skirt ... 51.15 0.15 mm (2.014 .006 in)Thoroughly lubricate piston pin with clean engine oil prior to inserting into piston group and rod assembly.(7) Piston skirt.