1984-1986 Mercury Force 4HP Outboards Service Manual, Page 45Get this manual
4Check crankshaft bearings and seals AInspect bearing for rust, fractures or wearReplace if necessary
BInspect bearing seal for nicks, tears or wearReplace if necessaryCInspect lower main bearing for signs of rust, fractures or wearReplace if necessary
EMERY CLOTH
5Check cylinder head: AUse spark plug tap to clean carbon from spark plug threads in cylinder head
Figure 21 Resurfacing Cylinder HeadCheck flatness of cylinder head by laying gasket surface on piece of plate glassMeasure at various points between cover and plate with feeler gaugeFigure 20
6Check cylinder block and crankcase:
Using an inside micrometer or dial indicator, measure the inside diameter of the cylinder at three pointsMeasure 14 inch down from the top, 14 inch up from the exhaust port and about 316 inch down from the lower edge the inlake portThe maximum difference allowed between the largest and smallest of the measurements (taper) is 0.002"" (0.05 mm) Figure 22Also.take measurements 90" from first set