O.S. Engines FS-91S II (P) - Manual (Page 9)

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NEEDLE-VALVE EXTENSION
The needle-valve supplied with this engine is designed to
accept an extension so that, when the engine is enclosed in a
cowling, the needle-valve may be adjusted from the outside.
An L-shaped rod, of appropriate length, may be inserted in the
needle-valve knob centre hole and secured by tightening the
set-screw with a 1.5mm Allen key.
THROTTLE LINKAGE
Before connecting the throttle to its servo, make sure that the
throttle arm and linkage safely clear any adjacent part of the
airframe structure, etc., as the throttle is opened and closed.
Connect the linkage so that the throttle is fully closed when
the transmitter throttle stick and its trim lever are at their
lowest settings and fully open when the throttle stick is in its
fully-open position..
Carefully align the appropriate holes in the throttle arm and
servo horn so that they move symmetrically and smoothly
through their full travel.
Fit these in the following sequence.
Screw the header pipe into the cylinder head until it " bottoms
", then unscrew sufficiently to achieve the desired exhaust
angle and tighten the locknut securely with a 14mm wrench.
Screw the silencer onto the outer end of the header pipe and
tighten the other locknut.
The application of a heatproof silicone sealant to the threads of
the exhaust system is recommended to reduce the risk of joints
loosening and the leakage of exhaust gases and oil residue.
EXHAUST HEADER PIPE & SILENCER
Reminder:
Model engines generate considerable heat and contact with
the header pipe or silencer may result in a serious burn.
If you need to tighten the silencer joints, which may loosen
when they are hot, use a thick folded cloth for protection.
FUEL LINES
For fuel line, use, heavy-duty silicone-rubber tubing of
approximately 2.5mm inside and 5.0mm outside diameter.
Note: Be sure to use a muffler-pressurized fuel feed
system.
It is advisable to fasten connections with tube clips or secure
binding.
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