4. Do not overheat the engine. This goes along with
keeping it clean and not over-leaning the engine.
5. Do not use a fuel with a low oil content. Make sure
you use a fuel from a reputable manufacturer,
such as DuraTrax Red Alert.
6. Avoid using old fuels in the engine. Always run all of
the fuel out of the engine. After running for the day,
use an after-run oil and work it into the engine by
turning the flywheel or pulling the engine recoil slowly.
7. Do not use a fuel with a nitromethane (often called
nitro) content over 20%.
8. Do not scratch the piston or cylinder sleeve. Avoid
jamming something into the exhaust port when
removing or re-installing the clutch or flywheel.
Use a special tool called a crankshaft locking tool,
which is installed in the glow plug hole.
9. Do not use silicone sealer on the engine joints.
Silicone sealer contains acetic acid, which is
corrosive if it gets inside your engine.
10. Do not allow any water inside the engine. This
sounds easy, but temperature changes can cause
condensation inside the engine. This is a good
reason to use an after-run oil. Store your engine
inside the house, not in a garage or shed where
there will be temperature extremes.
If you are having problems with your engine consult
the engine troubleshooting flow chart on page 19.
The following are some potential problems.
Glow Plug
The glow plug is an item that will wear out and need
replacement from time to time. It is a good idea to
remove the glow plug before your first run, heat it and
see how well it glows. You should see a bright orange
glow from the filament. If a coil or two will not glow or
the plug will not glow at all, replace the plug. If the
engine quits when you remove the glow starter, the
plug might need to be changed, although this may be
because you are running too rich and need to screw in
your high-speed needle some. Look at the glow plug
when you are running the engine. If you see some
bubbles coming from around the plug, replace the
glow plug (copper) gasket, or both the plug and
gasket. The only real way to test a glow plug is to
replace it. Make sure you have a spare plug or two on
hand every time that you run the Street Force GP.
Fuel
Fuel can go bad. The main ingredient in model fuel is
methanol, which is basically an alcohol. Alcohols can
absorb water out of the air, so keep your fuel jug
capped at all times. Store your fuel out of the sunlight
and in a cool place. Bad fuel is one of the most difficult
problems to diagnose in engines. If you have tried
everything you can think of to remedy an engine that
is not running correctly, try using some fresh fuel.
Fuel line is susceptible to pinhole leaks. You cannot see
the hole in the fuel line, but if you see air bubbles in the
line going to the carburetor, replace the fuel line. Another
symptom of a leak in the fuel line is a surging engine. The
properly tuned engine will surge when the air bubbles hit
the carb. It is basically leaning out the mixture.
To keep dirt out of the engine, use an inline fuel filter
on the fuel line running from the fuel tank to the
carburetor. Dirt can get caught in the needle seat and
cause an inconsistent running engine. If you suspect
that some dirt has lodged itself in the carb, remove the
needles and clean the carb with denatured alcohol or
fuel. It can help to use compressed air to blow out the
fuel passages as well. Dirt can get into your carburetor
and engine through the air filter. Ensure that your air
cleaner has a good seal to the top of the carb.
Periodically wash the air cleaner foam element and re-
oil the filter. Any air cleaner that has a torn element or
a bad seal should be replaced immediately.
Overheating
One of the worst things you can do to your engine is
overheat it. The oils that lubricate the engine are
carried in the fuel. If your engine is set too lean, there
will not be enough oil in the engine to lubricate the
internal parts. This will cause premature wear in the
engine and cause damage.
Toe-In/Toe-Out:
This refers to the angle of the front tires
when viewed from above when the suspension arms
are level. If the fronts of the tires angle in, it is called
“toe-in” and if the fronts of the tires angle out, it is called
“toe-out.” This is adjusted by lengthening or shortening
the steering rods - the rods that run between the front
hub and the servo saver. Normally a small amount of
toe-in is used to make the touring car track straight at
high speed. Too much toe-in will make the touring car
difficult to turn as well as reduce the overall top speed
because of tire scrub. Sometimes a small amount of
toe-out will be used to help the steering. As a general
rule use a small amount of toe-in.
PERFORMANCE TUNING
13
