ZHEJIANG KAYO MOTOR CO., LTD.
www.kayomoto.com
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Engine inspection and maintenance
Cylinder head part
Precautions
1. The camshaft journal is lubricated by the oil passage on the cylinder head. No foreign matter
can enter the oil passage. The camshaft bearing rotates flexibly without jamming. The pressure
reducing valve sling rotates flexibly and can return normally, otherwise it will easily cause
engine damage.;
2. When assembling, the camshaft hole of the cylinder head must be smeared with proper
amount of lubricating oil;
Main parameters and maintenance standards of cylinder head parts
No.
item
standard
value
Repair limit value
Remar
k
1
Free length of valve spring
40.5
39.5
2
Valve
clearance
Intake valve
0.04~0.06
<0.04 or
＞
0.06
Exhaust
valve
0.04~0.06
<0.04 or
＞
0.06
3
Camshaft base circle runout
0.01
0.03
4
Valve guide aperture
φ5.475~φ5.4
87
φ5.5
5
Valve stem
diameter
Intake valve
φ5.45~φ5.46
5
φ5.45
Exhaust
valve
φ5.43~φ5.44
5
φ5.43
Troubleshooting
No. Performance
Possible Causes
1
Low air pressure in
the cylinder
Valve
Incorrect valve clearance adjustment
The valve is not tightly sealed
Wrong gas timing
Broken valve spring
Cylinder
head
The spark plug is not connected tightly to the
cylinder head
Damaged cylinder head gasket
Cracks or blisters in the cylinder head
Cylinder,
Piston ring clearance is too large or broken
