MV Agusta 2008 F4 312RR 1078 Workshop Manual page 26

Measuring compression in the cylinder
The following tools are necessary in order to carry out
this procedure:
Spark plug key: n° 800089013
B
Compression measurer
Adapter for the compression measurer.
A)Heat the motor to the usual functioning temperature
(of regime);
B)Turn the motor off, remove covering structure, tank,
air box and remove the spark plugs;
C)Measure cylinder compression.
Drag the motor into rotation by means of the starting
motor with the butterfly valve completely open until the
compression measurer indicator (compessionmeter)
no longer rises; the compression measurement
obtained is the maximum.
Be sure the battery is completely charged.
NOTE
Cylinder compression control (280 rpm-min.)
Engine Type Min. Press.(bars) Max Press. (bars)
F4 1078
- Repeat the procedure for the other cylinders.
N.B.: If the compression in the cylinder is lower than
the minimum value of the reported range, check the
following points:
A) carbon deposits on the walls of the combustion
chamber and on the piston ceiling;
B) lthe head gasket is not of the correct measure-
ments;
N.B.: If the compression in the cylinder is lower than
the minimum value of the reported range, check the
following points:
A) The seat of one or more valves is damaged and
the valves do not maintain the compression pres-
sure;
B) One or more valves have null functioning play;
C) The piston, cylinder play is excessive;
D) The cylinder head is twisted and/or the head gas-
ket is damaged;
E) Excessive play between ring and cable.
7,5 14
Maintenance
Before carrying out the compression trial,
NOTE
accurately check the battery tension since
the compression value which appears is
quite influenced by the rotation velocity of
the motor, and consequently by the bat-
tery tension.
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