POWERHEAD
Page 4-24
90-826883R2 JUNE 1998
4. Check each cylinder bore for an out-of -round “egged shaped”cylinder. A maximum
of 0.003 in. (0.076mm) is allowable. If out-of-round is more than 0.003 in. (0.076 mm),
cylinder block and crankcase cover must be replaced.
MERCOSIL BORE --
ALL MODELS S/N OG202750 AND ABOVE
1. Inspect cylinder bores for scoring, scuffing or a transfer of aluminum from piston to
cylinder wall. Scoring or scuffing, if NOT TOO SEVERE, can normally be removed by
honing. If a transfer of aluminum has occurred, a diluted muriatic acid such as “TIDY
BOWL CLEANER”should be applied to the areas of the cylinder bore where transfer
of aluminum has occurred. After the acidic solution has removed the transferred alu-
minum, thoroughly wash the cylinder bore(s) with hot water and detergent to remove
any remaining acid. Cylinder walls may now be honed to remove any glaze and to aid
in the seating of new piston rings.
2. The cylinder block is Mercosil and if necessary can be rebored to 0.030 in. (0.762 mm)
oversized.
3. Check each cylinder bore for an out-of -round “egged shaped”cylinder. A maximum
of 0.003 in. (0.076 mm) is allowable. If out-of-round is more than 0.003 in. (0.076 mm),
cylinder block and crankcase cover must be replaced.
MEASURING CYLINDER BORE
1. Measure ring traveled area of cylinder bore at 3 depths, (6 places) by positioning mea-
suring instrument in-line with and at right angle (90
°
) to piston pin centerline.
2. If cylinder bore is tapered, egg shaped or out-of-round by more than 0.003 in. (0.076
mm), replace cylinder block.
TOP
CENTER
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