Leakage Testing; Preparatory Steps - Stihl TS 400 Manual

STIHL TS 400
- Remove gasket.
Note: When fitting muffler, position
new gasket so that the bead (1)
points towards the muffler.
• Compress and remove the clip.
• Draw out the spark arresting
screen.
- Clean the spark arresting
screen; fit new screen if
necessary.
5.2

Leakage testing

Defective rotary shaft seals and
gaskets or cracks in the castings
cause leaks through which
supplementary air can enter and
change the composition of the
fuel/air mixture taken in.
Above all, this makes it very much
more difficult, if not impossible, to
set the correct idle speed.
In addition, it also prevents a
faultless transition from idle to full
or part-load operation.
The crankcase can be tested to
ensure it is absolutely tight with the
aid of the carburetor / crankcase
tester and the vacuum pump.
5.2.1

Preparatory steps

- Remove shroud, see chapter 5.5.
• Unscrew the muffler screws
half-way.
• Slide a sealing plate (1) between
muffler and cylinder exhaust port
and tighten both the upper screws.
Note: The sealing plate must fill the
full width between the screws.
- Remove carburetor,
see chapter 10.3.
- Set piston to upper dead center
(UDC) (can be seen through the
inlet port).
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