General Hints on Starting Engines
All moped engines operate on the same principles.
Every engine needs
Compression, good fuel, and good spark to run. If your machine has been
sitting for a long time, there are a few things you should check out
trying to start the engine.
| 1. Check to see
that the engine turns over, and has compression. To do this, remove the
spark plug and try to turn the engine over with the starter. If it
make sure the kill switch is "off" so you do not get a shock from the
wire, and put your finger over the spark plug hole firmly enough to get
a good seal. Crank the engine over, and it should have enough
to "pop" your finger off the hole.
2. With the plug
attached to the coil wire, lay the plug against the block so that it is
grounded. Turn the engine over with the kill switch on, and you should
see a bright blue spark between the electrodes on the spark plug.
3. Look in the
fuel tank. Check for sediment, or water pooled at the bottom of the
Water is heavier the gasoline, so any that is in the fuel will gather
the lowest part of the tank. A flashlight works well to see the bottom.
If the fuel in the tank is more than a month or two old, it should be
In order for the
engine to start, the good fuel must get into the carburetor. If your
has a drain screw, open the screw and drain out the old fuel until you
see the fresh fuel coming out.
4. Turn the engine over
while holding your hand about 2-3" from the exhaust tip. You should be
able to feel air pressure coming out of the muffler every time the
turns over, proving that the exhaust pipe is not plugged.
5. Set the choke and
turn the engine over. After several cranks, the engine should start, or
at least start to "pop". If it acts like it wants to start, but will
keep going, turn the throttle to wide open and continue cranking. If it
still does not go, reset the choke and try again.
6. If the engine still
does not start after several tries, remove the spark plug again to see
if it is wet with oil, or fuel. If it is dry, make sure that fuel is
into the carburetor from the fuel tank. You can do this by removing the
fuel line from the fuel tank and turning on the gas valve. Fuel should
flow out in a steady stream. If your machine has a vacuum operated fuel
valve, locate the vacuum line on the fuel valve and remove it where it
hooks to the intake manifold, then apply vacuum to it, either by using
a vacuum pump, or by just sucking on it carefully. (make sure you are
sucking on the fuel line!) This will operate the valve, and fuel will
out in a steady stream, as long as the vacuum is applied.
7. If you have
removed the spark plug and it is wet, the spark plug may be fouled, or
the fuel is not good enough to burn. If your spark plug is glossy black
on the tip, it is fouled for sure, and cleaning will not help. The plug
must be replaced.
8. If your engine turns
over well a few times, then locks up, remove the spark plug and
to turn it over again. It is common for an engine that has been sitting
for a long time to fill with oil in the crankcase causing a hydraulic
This will be obvious as the spark plug will have a drop of oil on the
when you remove it, and oil will spurt out the plug hole when the
is turned over quickly with the spark plug out. All this oil must be
out before the engine will run, as the plug will be fouled with oil
time you turn it over. This is best accomplished by turning the moped
down and cranking the engine repeatedly to expel all the oil. Do not
the engine to turn, as damage to the crankshaft may result.
9. If everything
seems ok, but still no start, make sure that your throttle is working
On many mopeds the choke will not operate properly if the throttle is
If the idle adjustment screw is in too far, it will act the same as
the throttle, so the engine will not get enough fuel to start cold.
the throttle open, and let it snap shut. You should hear the throttle
"click" down in the carburetor as it closes. This tells you that it is
closing all the way, and is not being held open by a sticky throttle
or by being adjusted too tight.
10. If you still are
not getting fuel on the spark plug after choke is used, and you are
the fuel is making it into the carburetor, remove the air cleaner boot
from the back of the carburetor and place your hand over the end of the
carburetor. When the engine is cranked over, you should feel your hand
being sucked into the carb. It should also get wet with fuel. This will
force choke the engine, and after doing this for a few cranks, the
will draw fuel into itself. Then hold the throttle wide open, and crank
again, to see if you get a "pop". If this method gives you a result,
are pretty good that the carburetor needs to be cleaned out, as it will
not flow fuel without a large amount of vacuum.
Scooter Therapy Inc
12 North Few
Street | Madison,
1-608-255-1587 | E-mail
12 N. Few
9-6 Saturday, 10-3 CST
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