Manual

Engine Maintenance And Servicing Manual

——Measure valve spring free length and spring force:

——Grinding the valve and the valve seat with the valve

conical angle (Intake valve and exhaust valve):

44°30′— 45°30′

Valve seat sealing width:

1.75 — 2.32mm

Installation:

——Before installation, make sure that cylinder head has been

cleaned without any grinding material on cylinder head, valve or

valve guide.

——Lubricate the valve stem and guide with clean engine oil.

——Install the valve. Notice that the intake and exhaust valve for

478 and 480 are not interchangeable. Refer to the previous valve

mark for valve assembly.

——Press the valve spring assembly with oil seal onto the top of

valve guide. Apply engine oil on the intake and exhaust valve guide

edge where the valve seals are installed for preventing valve lock

piece groove from damaging oil seal lip. You may protect the valve

lock groove with tape and remove the tape after installing the valve.

——Install the valve spring and spring seat. Compress the spring seat

to expose the lock piece groove with a special compression tool. Then

put the lock pieces into it and release the compression tool slowly and

remove the tool.

——Put the cylinder head on a wood lump after all lock pieces are

assembled. And tap the small head of the valve stem with a plastic or

copper hammer to fit for the valve mechanism.

Compression (mm) Spring load (N) Spring free length

=37.084 422

=27.7 892.7

=27.0 945

=47.2

Fig.42

Fig.43

Fig.44

Fig.45

Fig.42

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