Evolution Engines 120NX - Manual (Page 6)

11 10
can touch the cylinder comfortably.
6. Repeat Step 5 one more time and then the rest of
the break-in can be accomplished in the air. Set your
engine’s needle valves per the instruction manual. If
anything, continue to err slightly on the rich side and
your engine’s performance will continue to improve
over the next gallon of fuel or so.
Why would fuel go “bad”?
The largest portion of the fuel is methanol (alcohol).
Methanol is hygroscopic; it attracts moisture. This can
cause your fuel to be contaminated with water, which will
cause poor engine performance. Additionally, the UV rays
in sunlight will eventually break down the nitromethane if
the fuel jug is stored in sunlight for long periods of time.
How can you tell when your fuel has gone “bad”?
The first indication will generally be the inability to start
the engine at previously run needle-valve settings.
Another clue might be that the engine has very poor idle,
runs but bogs down tremendously during run up and/or
will not attain the same rpms that you are used to.
How do I keep my fuel fresh?
If you have the opportunity, look for someone at a flying
field on a sunny day who has a jug of fuel that is only
1/4 full. What you may notice is that there are droplets
attached to the top and sides of the container. This is
the moisture in the air that is condensing inside the jug
because of the greenhouse effect of the semi-translucent
plastic jug. This will also occur within a metal fuel can as
the sun warms the contents.
You can combat the effects of the moisture in the air by
squeezing all the extra air from your fuel container at
the end of the day or transferring your fuel into smaller
containers as the level of the fuel is reduced in your
gallon jug. Many pilots will invest in 1/2 gallon or quart-
size containers and only bring that amount of fuel to the
field on any given day. This allows their main supply of
fuel to stay at home in a controlled storage environment,
virtually ensuring problem-free fuel.
How to Tell If Your Glow Plug Is Bad
The glow plugs on the market today are designed
to provide good service to the user and may last a long
time or a short time, all dependent upon the way you
choose to operate your engine.
Physical indications that you might need to
change the glow plug are:
1. Twisted or mangled glow plug elements (usually
caused by too high a compression ratio).
2. Small “bumps” are attached to the glow plug
element. This will generally be most noticeable
during the break-in process. These are actually
tiny pieces of aluminum that have attached to the
element and will severely hinder the operation of
the glow plug.
3. The glow plug element is no longer shiny but is dull,
almost a white powder color. (This just comes with
age and is a by-product of the catalytic reaction).
The shinier the wire, the better the catalytic reaction
can be.
Operating indications that you need to change
your glow plug are:
1. The glow element will not light with a charged glow
igniter. This indicates that there is a physical short
or breakage in the element wire itself.
2. Glow plug lights but the engine will not continue
running once the battery is disconnected. (This is
usually an indication of the microscopic particles
discussed earlier.)
3. Glow plug lights, engine runs but there is a
perceptible loss of rpm at full throttle when the
battery is disconnected. This is a typical indication
that the white powder residue is building to the
point that the catalytic reaction of the glow plug is
no longer anywhere close to being optimum.
Troubleshooting Guide
Engine Won’t Fire
• Glow starter not charged
- Charge glow starter
• Glow plug burnt out
- Replace glow plug
• No fuel is getting to the carburetor
- Check tank, fuel lines reversed
• The starter is reversed
- Reverse the polarity on the starter cables
Engine Quits Repeatedly
• Needles need adjusting
- See adjustment procedure
• Bad or old fuel
- Replace with fresh fuel
• Worn out glow plug
- Replace with new EVOGP1 glow plug
Engine Runs Inconsistently
• Hole in fuel line
- Replace fuel line
• Bad or old fuel
- Replace with fresh fuel
Maintenance
After each flying session:
1. Fully drain the fuel from the tank.
2. Start the engine and run it until the fuel is
completely run out of the engine.
3. Try starting the engine three more times or until
it will no longer fire. This gets all the fuel out of
the engine.
Now add several drops (about 10) of after-run oil
(EVOX10000 Evolution Engine's Blue Block Rust
Inhibitor) should be applied into the carburetor and the
engine should be turned over for a few seconds with the
starter. This will prevent rust and corrosion.
If you need additional help or have any questions, please call
Horizon’s Support Team. Horizon has trained technicians who
are qualified to answer your engine questions.
Evolution/Horizon Service Center
4105 Fieldstone Road
Champaign, IL 61822
877-504-0233
Disp Bore Stroke Weight Crank K
Items (c.i.) (mm) (mm) (oz) (ISO) Cylinder Propeller
EVOE1200 1.20NX" 30.3 27.4 23.502 5/16 x 24 Die Cast Steel 16 x 8 @ 8500 RPM
1.20NX Evolution Engines Specifications
Dimensions (mm) A B C D E* F G H
EVOE1200 45 58 25 60 92 111 5/16 x 24 42
F
H
G A
D C
E = height*
F = length
G = crankshaft thread size
H = muffler bolt spacing
B
* Height is from engine C/L to top of cylinder head