Yamaha F100B F100C Outboards Factory Service Manual, Page 133Get this manual
Cylinder body NOTE: Do not remove the ignition timing pointer from the crankcase3Remove the connecting rod bolts and the connecting rod capsNOTE: Be sure to keep the bearings in the order as they were removed, and to note the bearing color of the bearing After removing the connecting rods, mark each cylinder for identification4Remove the crankshaft, oil seals, and the piston assemblies
Checking the cylinder bore
1Measure the cylinder bore (D1D6) at measuring points a, b, and c, and in direction (D1, D3, D5), which is parallel to the crankshaft, and direction (D2, D4, D6), which is at right angle to the crankshaft
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Checking the piston diameter
1Measure the piston outside diameter at the specified measuring pointReplace if out of specification