ENGINE AND CARBURETOR ADJUSTMENT
• Now we propose you a basic adjustment system as a starting point, and after that another system to adjust it in a
more detailed and suitable way for competition.
• With the engine turned off, close to the maximum the low screw (L) and from that point open it a whole round more
about thirty minutes, approximately 1 turn plus 1/2 turn.
• Do exactly the same thing with the high screw (H) and open it a whole round more about thirty-ve minutes.
• Start the engine and then give it some soft gas blows when it has been stabilized, adjust the idle screw.
• This adjustment will allow you to start to wheel with a very good performance. Then and with the engine still warm
you will must nish to rene it doing some movements in the carburettor’s screw ( L, H and idle) in steps of ve
minutes and controlling carburetion looking at the colours of the spurk plug’s inside.
• In a big scale Zenoah engine, the colour taken by the spark plug’s central ellectrode’s ceramic indicates us the
adjustment at high r.p.m. whereas the colour of the metallic ring which covers it and where the spurk plug is screwed
in shows us adjustment at low r.p.m. In this way when your observe the spark plug after wheeling some turns we’ll
know exactly how the engine is carburetting all is range of revolutions.
• Central ceramic is able to show a range of colours form bright black or wet one with coal dust grains which means
very greasy, to a dry and matt greyish white, which means dangerously short. The desirable colours are:
-A matt and plain black (without coal dust) lightly cleared up which shows a tight but greasy adjustment, ideal
for training and little important qualifying rounds.
-A white coffee-like brown which shows an ideal high carburetion. The engine won’t miss us and will yield end
to end as many minutes as we wish. Ideal for a nal or sub nal with hot weather.
-A dark white or beige colour. The engine is giving all its potential very near its limit. If the atmosphere rises up
in temperature it might stay short. Ideal for important classicatory heats lasting ten minutes or nals with cold
weather.
• If instead of a beige colour the ceramic becomes greyish or dirty white, take immediately a screwdriver and open
the hi adjust an eight of a round or a bit more (between ve and ten minutes if it were a clock) since the engine is
warning you it’s going to heat up excessively any minute now.
• The metallic ring, which indicates low r.p.m. adjustment, can show itself.
-Wet black with much coal dust, which indicates us a adjustment too greasy in low r.p.m..
-Bright black without coal dust or with just a little in some area of the ring; it shows us an ideal low adjustment.
It will keep the engine greased allowing us to adjust high adjust to the maximum.
-Matt black without coal dust and clearing up, it indicates us the engine goes a bit short low adjust; if we rene
it very much hi adjust we are going to have problems in a few rounds.
-Dry dark brown or the ring’s metallic colour. Engine excessively dry, temperature problems and strange reac-
tions or too lively at low r.p.m.
• For these readings of the spark plug to be totally truthful avoid the car to be too much time to idle before turning it
off since the spark plug colours might vary.
• Use competition high quality oil for the mixture, like Contrast oil which has been specially developed for the condi-
tions and high performance features of the tuned engines.
• The high revolutions per minute Zenoah engine reaches require the use of oil which resists more than 20000 rpm
without faint. The use of non-adequate oils, although being from renamed branches, may increases in a considera-
ble way the wear and tear of the piston, the cylinder, of the seals and of the crankshaft bearings.
• Work with amount of oil will between 2,5% and 3,5%. This diminish the engine’s temperature and will improve the
sealed between the piston and cylinder.
• Use petrol mixed with oil recently. A mixture stored for some weeks may loose its lubricant properties or vary the
% of mixture.
• Zenoah engine requires some running when it’s used for the rst time, at least during the rst half an hour of wor-
king. This means a soft and careful driving with a little greasy carburetion.
• Watch over the state of the exhaust’s inside. A dirty exhaust with an excess of dust coal can make the engine’s
answer worse.
• Watch over the state of the air lter. A dirty lter with an excess of dust coal can be very dangerous for the engine
life.
• For the maintenance and revision of the engine, consult the Zenoah instructions handbook indications included in
the kit.
