Special Procedures Engine; Setting The Rpm; Adjusting Valve Clearance And Retightening The Cylinder Head Bolts - Whisper Power W-SQ20 User Manual

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
1500 (50 Hz) RPM. A RPM drop of 5% at full load is
acceptable. Therefore a no load setting should be at ±
1575 RPM = 52.5 Hz. Under no circumstances should the
RPM be under full load below 1470 RPM = 49 Hz. When
no cause can be found for a wrong speed, the setting can
be adjusted:
01 Engine speed adjusting screw
Fig. 30 Location engine speed adjustment screw.
It is very important to identify the correct setting assembly
(see fig. 30). The screw is to be locked in position with the
lock-nut.
EN / W-SQ20 for mobile applications / April 2010
01
5.4.2 Adjusting valve clearance and
retightening the cylinder head bolts.
Both procedures have to be executed with a cold engine.
When both procedures are executed be sure to retighten
the cylinder head bolts before adjusting the valve
clearance. When retightening the cylinder head bolts,
drain the coolant by removing the coolant drain plug (ref.
to fig. 4).
Loosen the bolts slightly, remove the rocker assembly (the
rocker arms, shaft, and stays) and then retighten the bolts
to the specified torque in the numerical order illustrated
(ref. to fig. 31).
Tightening torque cylinder head bolt:
Rocker stay tightening torque:
Fig. 31. Cilinderhead bolt tension sequence.
The clearance of both (intake and exhaust) valves should
be 0.25 mm in cold condition. Set the piston of the first
cylinder to be adjusted to top dead centre (T.D.C.) of
compression stroke.
The T.D.C. of compression stroke can be found by
aligning the T.D.C. mark "O" on the crankshaft pulley with
the mark on the gear case
First align the T.D.C. mark for the No. 1 cylinder. Confirm
that the valves do not move up or down when the
crankshaft is turned about 20 degrees in normal and
reverse direction of rotation.
Fig. 32. Checking valve clearance (turning)
If the rocker arms move piston no.1 is on the T.D.C. of the
intake or exhaust stroke. In such case turn the crankshaft
TROUBLE SHOOTING
118 ± 5 Nm
10-20 Nm
35