TOHATSU NB-1000 Service Manual page 109

Cleaning
1. Remove all carbon accumulation from exhaust port areas and
cylinder head combustion chambers.
2. Use gasket remover and Scotch-Brite Abrasive Pads to
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remove all traces of gasket and sealer from the cylinder
block, crankcase, cylinder head, intake manifold, exhaust covers,
and air silencer.
DO NOT use a metal scraper on gasket surfaces
or the mating surfaces of the crankcase.
3. Remove aIl carbon deposits from the tops and ring
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grooves of the pistons.
A ring groove cleaning tool can be made by breaking
an old ring and grinding an ang/e on its end. Do not
damage the grooves when cleaning.
4. Wipe off all traces of oil and thoroughly wash the cylinder
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block and crankcase with warm, soapy water. Air dry the
cylinder block and crankcase. Dry all holes and passages with low
pressure compressed air.
5. Coat the cylinder walls with genuine engine oil or certified TC-W3
oil to protect them from corrosion.
Inspection
Before inspection of the powerhead, aIl components
must be perfectly clean and free of contaminants.
After the inspection, when it is found that the
cylinder(s) requires re-finishing or boring, all the
works have to be done in the approved
machining plant. Light scuffing or burn does not
require boring for removal. Use water-resistant
sand paper of around #320 to remove the
damages, and then use #400 and #600 to finish.
1. Visually inspect all internal components. lnspect for unusual
wear patterns, heat-related discoloration of bearings, broken parts,
and scuffing or damage to aluminum parts.
2. Inspect the intake manifold and reed valves. See lntake Manifold
in Section 3.
1-/ 2-Cylinder
CAUTION
NOTE
NOTE
CAUTION
POWERHEAD
T1687
T1224
T1690
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