Benelli ZAFFERAN 250, Service Manual

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11. Cylinder Head/Valve
Preparation documents -------------- 11.1
Failure diagnosis-----------------------11.2
Cylinder head---------------------------11.3
11.1
Preparation documents
Function of the cylinder head
:
The cylinder head is used to seal the cylinder and forms a
combustion chamber with piston to bear the high temperature and high pressure combustible gas,
and to intake and exhaust gas through the valve actuating mechanism.
Notes:
In order to assure a seal between the cylinder head and cylinder body, the cylinder head bears a
strong bolt pretightening force. Pretightening force: 28 Nm.
All parts shall be cleaned and blown by high pressure air before inspection.
Preparation standard
Unit: mm
Item Standard value Usage limit
Cylinder pressure
1.2Mpa
－
Flatness of cylinder cover
0.03 0.05
Valve
guide
Valve clearance
Inlet
0.08-0.1 0.09
Exhaust
0.1-0.15 0.10
ID of valve guide pipe Inlet/Exhaust
4.5-4.512 4.532
Clearance between
valve lever and valve
guide pipe
Inlet
0.015-0.037 0.07
Exhaust 0.03-0.052 0.08
Width of valve seat Inlet/Exhaust
0.8 1.4
Valve
spring
Free length
Inner
31.92 29.92
Outer
36.6 34.4
Rocker
Diameter of rocker hole Inlet/Exhaust
12.01-12.028 12.07
Diameter of rocker shaft Inlet/Exhaust
11.983-11.994 11.94
Clearance between
rocker hole and
rocker shaft
Inlet/Exhaust
0.016-0.045 0.10
Camshaft Cam height
Inlet 33.27 33.14
Exhaust
33.1 33