XCell Spectra-G Model – Additional Operators Guide
Page 6 of 16
Copyright
12/5/2004
Miniature Aircraft USA
3. Setup Guidelines
The following tips will ensure that the engine and model have been configured for best results.
These are of course not the only way to do things however these have been repeatedly proven to
work.
3.1. Fuel System
Follow the assembly manual for installing the fuel system. This will result in three fuel lines to
the tank
•
A vent line
•
A primer bypass from the top of the carburetor
•
A fuel feed from the carburetor
This configuration will apply regardless of tank location. Use only fuel line compatible with
gasoline products. The kit includes Tygon fuel line, which can be obtained from MA USA or
your local hobby store.
As per the instructions, it is preferable that the line used as the fuel feed remains as one
piece. The addition of any filters or “T” fittings into this line can trap air bubbles that will later
enter the fuel inlet and may cause the engine to hesitate during flight. Keeping the fuel feed
line as one continuous piece will eliminate this possibility. The included filter must be
installed in the fuel tank. To remove any unused fuel from the tank, we suggest you simply
remove the fuel line from the carburetor fuel inlet and pump it out through that tube (you will
need to remove the plug on the vent line to do this)
As delivered from the gas station pump, gasoline is not particularly clean. It is often
contaminated with particles of one sort or another. The kit is delivered with a very fine fuel
filter to minimize the chance that these fuel contaminates can enter the carburetor. Several
different filters were tested and this particular one offered excellent fuel pickup. You may of
course use other types of filters although most of the standard glow-fuel filters do not
adequately filter gasoline because the filter elements are too coarse.
The fuel vent line is capped with a one way air valve. It is important that this valve remain in
place. The Zenoah carburetor contains a fuel pump that will pull fuel from the tank. If the tank
is not vented, it will collapse from the vacuum that forms and eventually cause the engine to
stop running. However an open vent line can allow raw gasoline to run out of the vent line if
your flying style includes inverted flight. The one-way valve allow the tank to vent, but will
prevent fuel from escaping. It also requires that the capped “T” fitting be including in this vent
to allow the tank to be filled normally, since otherwise trapped air could not escape during
fueling.
3.2. Exhaust System
Miniature Aircraft has tested several different exhaust systems for use with this gas model.
a) The Zenoah muffler that comes as standard equipment with the motor, while not
having an appealing sound, will work fine and result in a cooler running engine.
b) In conjunction with MA, Hatori has developed a muffler for use with the Zenoah
G23/G231/G26 engines. Miniature Aircraft recommends this muffler, which was
specifically designed for use with this helicopter. It is significantly quieter and allows a
broad power curve.
