Sachs SA 280A - Page 43

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TEST-RUNNING AND RUNNING-IN THE ENGINE
Test-running
Start the engine and let it warm up ( open the choke os soon as the engine starts up ).
Final adjustment
Adjust the desired idling speed of the e ngine by m ea ns of the idling adjustment s cr ew.
Then
slowly vary the set ting of the adjusting screw of the idling j et so that the engine
speed increases smoothly when the throttle is opened . The main jet is correctly ad -
justed
when the engine gives satisfactory two-stro ke operation under load and only
slight fumes are discharged from the exhaust (HL 242 A with fixed main jet). If there
is excessive exhaust smoke under load, turn main jet adjusting screw clockwise
(closing) until smoking stops and engine runs satisfactorily.
If the idling speed fluctuat es too much or is too high , turn the idling jet adjusting screw
anti-clockwise (to open th e jet) until th e engine runs smoothly at l ower speed w ithout
beginning to discharge more smoke f ro m the exhaust.
Running-in period
Even the finely machined surfaces of pistons and cylinders are not so smooth as the
surfaces of parts wh ich have been slid in g against one another for some time. For
this
reason every piston requires to be run in during the initial period of operation.
This does not call for any special precautions, ho wever, but si mply mea ns that the
engine should not be required to give its maximum output d uring the first 20 ... 30
running hours.
No speci al gasoline / oil m ixt ur e is required during the runnin g-in per iod, and conse-
quently there is no need to add any special oils.
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