MVVS 50 IRS - Manual (Page 4)

Caution!!! The engine must be stopped while you adjust the carburetor in order to
prevent injury by the propeller.
Caution!!! Never close the choke valve completely when the engine is operating!
The choke valve is set to allow minimum air flow only when fully closed, which could
cause damage to the intake reed valve.
If the throttle pull rod is not equipped with flexible element it is recommended NOT to
put off the throttle valve spring. Otherwise the vibrations of the engine can cause
excessive wear of the throttle valve shafting and with this deteriorate the carburetor
function.
Adjusting Carburetor’s Position
You can turn the rear cover by 90 ° which makes it possible to adjust the carburetor’s
position (especially its adjusting needles) when fixing it in the model.
How to dismantle the rear cover:
Unscrew the two M4 screws that hold the carburetor in place, remove the pressure hose
from the carburetor (mind the gasket under the carburetor), remove the carburetor and
loosen four M5 screws along the crankcase (Caution! Do not loosen the M4 screws that
fix the reed-valve to the rear cover).
Remove the rear cover by pulling it out of the crankcase – never use a hammer or any
other similar tool. The rear cover is sealed in the crankcase with two sealing rings –
therefore more strength is needed, however, it must always be pulled only!
Make sure you disassemble the engine in a clean environment!
Position the rear cover as desired, carefully insert it in the crankcase and tighten the
screws. Do not forget to insert the gasket when reassembling the carburetor.
Starting and running in a new engine
Before you first start the engine, screw the plug in and tighten it up. Follow the
instructions on the box of the spark plug. Make sure that the plug socket is fitted in place
and fastened down properly; pull the wire ring over the hexagon.
Fix the ignition sensor in proper position above the magnet with screws enclosed.
Unless the spark plug is inserted in plug socket, never turn the engine with ignition
turned on. This could lead to ignition damage!
1) Make sure that the ignition is switched off, the choke valve is closed and the throttle
valve is about half opened. Then give the engine 3-4 turns, provided that the carburetor is
not flooding. If it is flooding, only give the engine 1-2 turns.
2) Switch the ignition on, open the choke valve, set the throttle at slightly higher idle
speed and give the engine a few counter-clockwise flips. If even after the fourth flip,
there is no indication of the engine starting, or firing, give the engine 2 turns following
the instructions in paragraph 1 above. Then proceed according to instructions given in
paragraph 2.
3) If the engine does not start even after another set of flips open the throttle to maximum
and give the engine approx. 4 turns. Switch the ignition off and on again and restart the
engine with throttle turned slightly down and the choke valve set open.
4) If the engine still would not start, unscrew the plug and check its contacts. Clean any
possible petrol moisture (i.e. an indication of engine flooding) and screw it in again.
Further starting should only be done with the throttle turned down. If the plug is dry then
probably not enough fuel has been drawn into the carburetor. If that is the case, check the
fuel feed and then return to the instructions given in paragraph 1.
If the engine starts to run backwards do not open the throttle - stop the engine
immediately! Otherwise the engine can be damaged!
Having started the engine, leave it running for about 5 minutes at a higher idle speed.
Then run it in for approx. 20 minutes while changing revolutions from idle to ½ - ¾ of
the range and shortly holding each position - gradually prolong the holding periods. After
10 minutes of operation open the throttle to maximum for a period of about a minute. At
this point stop the engine and let it cool down. Then restart it and check the adjustment. If
everything is all right, you can make your first flight. During the first few flights do not
overload the engine and do not let it run at high revolutions for long periods of time (very
important during hot weather). Use up all fuel that was mixed with the oil that is included
with your engine. From now on, fuel and oil should be mixed in the proportion 40:1.
· DO NOT PROCESS THE RUNNING-IN AT IDLE SPEED!
· A COLD ENGINE SHOUL BE WARMED UP BY SHORT
ACCELERATIONS (1-2 SECONDS)