Technical information

TROUBLE SHOOTING

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.

Figure 16: Setting assembly

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 Whisper 3.5, 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