1976 Evinrude 40HP outboards Service Manual, Page 50Get this manual
Check cylinder for size and wall straightness by using an inside mi crometer or dial bore indicatorRefer to Section for specified dimensionsReplace cylinder block, or rebore block for oversize pistons if wear is in excess of .003 "Pistons and ring sets are available oversize I_ NOTE
If your shop is not equipped to rebOre cylinder blocks, write our Service Department about our reboring service
Carbon accumulation in the exhaust ports restricts the flow of exhaust gases and has considerable effect on performance of the motorCarefully scrape carbon from cylinder heads and exhaust ports with scraper or other blWlt instrumentExhaust ports and all exhaust passages must be free from carbon deposits to insure maximum performance
Figure 5-15"LOOSE" Mark on Piston
DO NOT scratch cylinder head gasket surface of cylinderUse surface plate to surface this areaSee "GASKET SURFACES" belowWith continued operation of the motor, the cylinder walls will take on glaze which reduces the effectiveness of the seal between the piston rings and the cylinder wallsThe result will be reduced compression and decrease in performance of the engineBefore reinstalling the pistons, break the glaze by using fine cylinder hone to refinish cylinder wallsA few up and down motions of the tool should be sufficient to remove cylinder wall glazeSee Figure 5-17Blowout all oil passages and drains