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Tuesday, September 11, 2007
Starting a New RC Model Nitro Engine
When you first purchase your new nitro RC car, probably
the first thing you’re going to have a time with is breaking in that new engine.
Sometimes, just starting it and getting it to stay that way will be your biggest
challenge. The engine is new and not worn into itself causes it to be stiff, low on
compression and causes even the best engines to be a complete bear when it comes to
getting going. Here are some tips to help you on your journey to an enjoyable RC
experience before you feel like throwing that new car against a hard brick wall.
The first thing you must do is ensure you have the correct fuel, usually a nice 20%
nitro content will do the job and give the engine maximum lubrication for breaking
in and also for a lifetime of enjoyment. Go ahead and fill the tank all the way.
Make sure all the batteries in the radio, car and if you have a glow igniter, are
full and in tip top condition. Take the glow plug out and while holding the sides,
connect the glow igniter to make sure the plug glows bright and hot, even while you
blow on it. Don’t touch the coil, it will burn you! If it glows nicely, put it back
in the head with the gasket and tighten it up with a snug turn, there is never a
need to wrench down on it hard. If it does not glow, check the battery in the
igniter and connections. If all that is good, try another plug.
Remove the fuel line from the muffler and give a good blow through it to ensure the
fuel reaches the carburetor; you should see the fuel go through the fuel line into
the carb. Reconnect the fuel line onto the muffler. At this point, it may not hurt
to put one or two drops of fuel directly into the air intake of the carburetor. This
acts as a choke and gives the engine a little boost to start. At this point, it
would be a good idea to make sure all radio gear is in working order and all the
servos are working as needed. Turn on the radio then the car’s radio gear, turn the
throttle trim up so you see about a 1/32” to 1/16” gap in the throttle body from
seat.
Most fuel mixtures are factory set, so go ahead and start the engine either by
pulling or electric start. Most engines will start, rev and then shut down. If you
have to pull more than ten times, stop, ensure there is fuel in the carburetor,
prime as needed, and try to start again. Don’t forget in anticipation to reconnect
the glow igniter. If you have success and the engine continues to run and idle, run
your model through at least three tank fulls of fuel not exceeding half throttle.
After the third tank, you’re ready to put your new model through all the fun it has
to offer.
Now here comes the tricky part, for those of you who may not be so lucky as to have
a smooth starting motor. As I’ve mentioned before, most nitro engine fuel mixtures
are factory set, but that doesn’t mean they will work all the time. I’ve found out
through rule of thumb, that most engines will work on these guidelines if your
engine continues to be a bear. The fuel mixture screw which is usually the top screw
on the carburetor and the one that is closest to the incoming fuel line, should be
set at 2 ½ turns from the seat. With a small screw driver, gently, and I do mean
“Gently”, screw this screw in while counting the turns clockwise; which means
turning it in while counting the complete turns. Do not force any carburetor screw
no time, no way. When it stops, it stops and be happy with that! Keep those number
of turns that you counted in your head; you may need that guidance later. Now turn
the fuel mixture screw out 2 ½ turns. Now comes the fuel/air mixture screw located
in the throttle body or horizontally in the throttle slide. Turn this screw inward
and count the complete turns until it seats. Keep this in mind for possible future
use. Turn the fuel/air mixture screw out 2 ½ turns.
Now you are ready to start the engine again, going through all the steps as you had
previously. Ensure there is fuel to the carburetor by blowing on the line from the
exhaust, open the throttle trim and connect the glow igniter. Try to start your
engine again, but don’t pull more than ten times. If it starts, you can adjust the
fuel mixture either in our out, depending on how the engine runs. If it’s spitting
and sluggish, screw it in. If the engine is revving too high upon starting, screw it
out. If the engine still won’t start, try to move the air/fuel mixture in or out,
more than likely out, by ¼ turn increments. Keep in mind, the air/fuel mixture screw
is very, very sensitive, but will only respond to how much the fuel mixture screw is
set. Your engine will start and run, but it will depend on these adjustments as to
how fast it will start and run.
Once the engine is running, ensure there is always a plume of exhaust coming out;
and your hand, when held at the exhaust, will be slightly wet from fuel. If this
does not happen, you have the fuel mixture too lean. This is where you would turn
the fuel mixture screw out just bit until the engine responds with zeal and idles
appropriately. You can now adjust the throttle trim on your radio to have your
engine idle as to not engage the transmission. If you idle is too high, the wheels
will continue to turn, which means the clutch is turning fast enough to engage. You
want your idle to be fast enough for your engine to run, but does not engage the
clutch. You will find an Idle adjustment screw just opposite the slide barrel; or on
the housing on a rotary carburetor, just parallel to the input shaft. Turn the Idle
screw in our out so the engine idles nicely while your radio throttle trim is in
center position.
Some hobby shops have an engine break in program like Wondertrail, where they will
break in the engine for you and adjust the initial settings on the carburetor, for a
small fee. This is one of the advantages of buying from your local hobby shop where
they can assist you if you have continued problems.
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