Cylinder Head/Cylinder/Piston - Service Information/Troubleshooting - Honda Nighthawk CB 750 1991 Service Manual

7. Cylinder Head/Cvlinder/Piston
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Service Information
7-1 Cylinder Head Removal/lnstallation 7-8
Troubleshooting 7-1 Cylinder Head Disassembly/Assembly 7-10
Camshaft Removal/lnstallation 7-2 Cylinder, Piston Removal/lnstalltion 7-12
Service Information
Camshaft service can be done with the engine in the frame.
The engine uses hydraulic tappets that eliminate manual valve adjustments. The hydraulic tappets have de-foaming
chambers. Fill the chambers with clean engine oil before assembling.
When adjusting the valve timing, do not turn the camshaft before installing camshaft holders and filling the de-foaming
chambers with engine oil.
Bleed air from the tappets thoroughly whenever the camshaft is removed (page 7-7).
Camshaft lubricating oil is fed through oil passages in the cylinder head. Clean the oil passages before assembling the
cylinder head.
Clean all disassembled parts with cleananon-flammable or high flash-point solvent and dry them with compressed air
before inspection.
Lubricate the camshaft journals and cam lobes with a 50-50 solution of disulfide grease and engine oil before reassembly.
When disassembling, mark and store the disassembled parts to ensure that they are reinstalled in their original locations.
Troubleshooting
Engine top-end problems usually affect engine performance. These can be diagnosed by a compression or leak down
test, or by tracing noises in the top-end with a sounding rod or stethoscope.
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If performance is poor at low speeds, check for white smoke in crankcase breather tube. If the tube is smoky, check for
a seized piston ring.
Compression Too Low, Hard Starting Or Pool
Performance At Low Speed
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Valves
-Faulty hydraulic tappet
-Burned or bent valves
-Incorrect valve timing
-Broken valve spring
-Uneven valve seating
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Cylinder head
-Leaking or damaged head gasket
-Warped or cracked cylinder head
Cylinder, piston
-Leaking cylinder head gasket
-Loose spark plug
-Worn, stuck or broken piston ring
-Worn or damaged cylinder and piston
Excessive Noise
Hydraulic valve tappet system
-Low engine oil level
-Contaminated oil
-Low oil pressure
-Damaged hydraulic tappet
Cylinder head
-Sticking valve or broken valve spring
-Damaged or worn camshaft
-Loose or worn cam chain
-Worn or damaged cam chain
-Worn or damaged cam chain tensioner
-Worn cam sprocket teeth
-Worn rocker arm and/or shaft
Cylinder, piston
-Worn cylinder and piston
-Worn piston pin and piston pin hole
Compression Too High, Overheating Or Knocking
Excessive Smoke
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Excessive carbon build-up in cylinder head or on top of
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Cylinder head
piston
-Worn valve stem or valve guide
-Damaged stem seal
Rough Idle
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Cylinder, piston
Low cylinder compression -Worn cylinder, piston, or piston rings
-Improper installation of piston rings
-Scored or scratched piston or cylinder wall