Got pinch?
Before we start troubleshooting, let's first make sure
the piston and sleeve aren't toast. Remove the
engine's glow plug, and rotate the flywheel with your
finger. As the piston reaches top dead center, you
should at least feel resistance as the piston is
“pinched” by the sleeve. This tight fit seals the
combustion chamber and is critical to engine
performance. If you don't feel any pinch, you probably
need to replace your piston and sleeve.
Check out the glow system
Even rank novices know to check out the glow plug when
starting problems occur, but few remember to check the
other half of the glow system—glow starter! Make sure
that your glow starter is fully charged (or has a
fresh battery), and its contacts are clean. Press the
glow plug into the glow starter and watch the coil; it
should almost instantly glow bright orange, and the
entire coil should glow. If the coil glows dull red,
or it doesn't glow at all (and you're certain the glow
starter is charged and making good contact), you need
a new plug.
If you have an electric starting system, the testing
procedure is the same, but you must remember to touch
the glow plug to the heat-sink head as you crank the
engine; if you don't, the glow plug won't light
because the circuit is incomplete.
Do the tighten-up
Make sure that the engine's heat-sink head and
backplate screws are fully tightened. Cinch them down
in the pattern shown to ensure even tightness; if you
torque the screws down completely one at a time,
you'll warp the parts and prevent them from sealing
properly against the engine. Pull-start engines
require the starter housing to be removed for
backplate access; be careful not to uncoil the starter
spring in the process! Slip a screwdriver between the
backplate and housing to prevent the spring from
popping out, then tape or rubber-band the assembly
after removal so it doesn't go “boing!” on your bench.
Speaking of sealing...
While you’re wrenching, take a look at the gaskets or
O-rings that seal the carburetor base and backplate.
If they’re damaged, replace them. A coat of Permatex
Ultra Copper sealant (or similar sensor-safe
automotive sealant) is also good insurance against air
leaks.
Know your limits
If your engine seems to start easily enough but shuts
down as soon as you let off the gas, check your
idle-limit screw—the little guy just in front of the
carburetor opening. Turn the screw so the carb still
has a 1mm (or so) opening when full brake is applied.
If the screw turns very easily, put a drop of
thread-lock on it to prevent engine vibration from
causing the setting to drift.
Needle needs
If you went nuts with your carb’s needle settings
before your starting troubles began, you should reset
them to factory specs. Lost your manual? For most
engines, a good starting setup is “flush” for the
low-end needle (adjust the needle so its screw head is
level with the opening in the carb body the screw head
sits in), and “two turns out” for the high-end needle
(gently turn the needle clockwise until it bottoms
out, then give it two full counterclockwise turns).
How’s that fuel tubing?
Even tiny pinhole leaks in your vehicle’s fuel and
pressure lines can cause erratic engine operation and
starting difficulties. When in doubt, replace the fuel
tubing; it’s inexpensive, and with all the color
options available, it’s a cheap and easy way to give
the chassis a new look.
Tanks for the memories
Your fuel tank isn't clogged, is it? Look for any crud
in the tank where the fuel pickup line is, and get it
out of there. Likewise, you should check your
vehicle's in-line fuel filter (if so equipped)
frequently; it can become clogged with debris and
impede fuel flow if not cleaned regularly. Finally,
consider removing the tank's plunger-type primer, if
so equipped; such primers are prone to air leaks.
After you've removed the primer, fill the hole with a
machine-thread screw and some silicone sealant.
Freshen up your fuel
If your jug of fuel spent the winter on the garage
floor, it has probably gone bad. Very bad. Dispose of
it responsibly, and get yourself a new gallon. Store
it in a cool, dry place away from sunlight and off the
floor. If you like to race outside or go on
extended-play missions outdoors, try to keep your fuel
out of the sun and heat. Trinity's Nitro Kooler bags
are the best way to prevent solar heating and protect
fuel in clear containers from light exposure.
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Now that you've ironed out any potential
problems, you're ready for a first-pull startup. Here's how to make it happen: |
1. Prime the carburetor. Remove the
pressure line from the exhaust pipe, and blow into
it; you'll see a solid jet of fuel fill the fuel
line up to the carburetor. When the fuel hits the
carb, stop blowing. Reinstall the pressure line.
2. Install the glow igniter. If it's a
cam-lock type, make sure it's secure. Is there a
gauge on top? Make sure the needle is in the
green.
3. Crack the throttle. Instead of
triggering the radio, just turn the throttle-trim
knob to open the carb another 1/2 millimeter or
so.
4. Pull the starter cord! Give a sharp tug,
and your engine should now be running. At the very
least, it should pop on the first pull and start
on the second or third (the extra tugs are usually
only required if the carb wasn't fully primed).
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by Peter Vieira
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