Technical information

TROUBLE SHOOTING
34 May 2010 / M-SC3.5 / EN
5.4 SPECIAL PROCEDURES ENGINE
5.4.1 Setting the RPM
RPM is set by the manufacturer and should not need
readjustment! However a very slight offset after running in
could occur. RPM can be measured by a frequency meter.
Before readjustment check any other explanation for the
wrong speed. Engine speed is set at the factory at nominal
3000 (50 Hz) RPM. A RPM drop of 5% at full load is
acceptable. Therefore a no load setting should be at ±
3150 RPM = 52.5 Hz. Under no circumstances should the
RPM be under full load below 2940 RPM = 49 Hz. When
no cause can be found for a wrong speed, the setting can
be adjusted: It is very important to identify the correct
setting assembly (refer to fig. 16).The screw is to be
locked in position with the lock-nut.
5.4.2 Tightening torques
Valve clearance, refer to Maintenance, §4.2.3.
Cylinder head screws M10x1,5:
51,9 to 56,8 Nm; 5,3 to 5,8 kgf-m.
Rocker arm bracket mounting: M8 x 1,25:
23.5 to 27,4 Nm; 2,4 to 2,8 kgf-m.
5.4.3 Measuring exhaust backpressure
The exhaust system must be of adequate size -1 5/8”/ 40
mm no more-no less -and maximal length (refer to
installation manual). This is true for all generators, but
specially for the M-SC3.5, because this small engine has a
small gas flow that easily can be blocked by a water trap in
the exhaust system. When any doubt; backpressure has to
be measured. An easy way to measure for back-pressure
is to use a water column. A water column can be made
visible in a plastic tube along a yardstick and fitting the end
to a hose connection to fit in the adaptor on the injection
bent after removing the exhaust temperature switch. The
bent A hanging down should not be to short helping to
damp the pulsating effect of the gas discharge that is
characteristic for a one cylinder engine. The water column
should be no more than 24 inches (60 cm.) of water (0,87
PSI - 0,06 bar).
Figure 17: Measuring exhaust backpressure.
MAXIMUM
69cm
27INCHES
Figure 16: Setting assembly