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Troubleshooting
One-Cylinder Engines
Living on a farm, homestead,
or just a small country estate, we often find much of the repair
work falls on us. Home repairs, appliances, and oh Lord, that
ever-present one-cylinder engine.
One-cylinder engines are most
common in sizes from 2 to 12 horsepower, carrying with it the
same basic characteristics of any gasoline engine. Trouble-shooting
the one-cylinder, however, is somewhat different from the 4,
6, or 8-cylinder.
When larger engines (those in
autos with 4 or more cylinders) are having problems, they will
usually run. Not always smooth, but they run. The one-cylinder,
when something is wrong, may not even start, let alone run. For
that reason the one-cylinder engine is a harder one to trouble-shoot.
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Trouble-shooting the small engine,
if you know how, can save you quite a bit of your hard earned
cash. Usually when one doesn't start we buy a tune-up kit when
it needs nothing more than a new plug. Worse yet, the plug may
just need cleaning. If we decide something is wrong with the
carburetor we usually buy a new one. Needless to say, much of
the work and expense that goes into the repair of a small engine
is unnecessary. We work by trial-and-error until we've spent
the price of a new engine and then take it to a mechanic who
works on it for 20 minutes and charges us for a full hour at
$24 per hour or more - just for labor! |
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Another important thing to remember
about a small engine if you live close to a small town is it's
sometimes a hard one to get repaired. Even though there are more
mechanics today specializing in small engines, there are still
towns that don't have a single small engines mechanic. Auto mechanics
usually don't work on lawn mowers or power chain saws.
There are only two things that
a small one-cylinder engine must have to run. It must have an
adequate supply of fuel, and the fuel must be getting into the
engine. Then there must be an adequate supply of ignition spark.
These two points are known to mechanics as "gas and fire".
First, let's take a closer look
at the gas. Before you go a single step farther, find the air
adjustment valve on the carburetor. Turn the screw to the right
as fall as it will go. Now turn it back to the left 2-1/2 turns.
If the carburetor works function at all, it'll work right there.
To test to see if the carburetor
is getting gas, remove the air breather. Set your throddle of
choke (or start) and pull the rope starter. Look into the top
of the carburetor. If gas is visible it is unlikely that the
problem is with the carburetor. If you think the problem might
still be gas, try this one. Using the palm of your hand, cover
the opening on top of the carburetor.
Pull the rope starter again.
Pay close attention (by feel) which way the air is going through
the carburetor. Is it sucking your palm into the carburetor or
is it trying to blow it out? If it blows, you have problems with
your valves. Chances are one of them is burned and will need
replacing - a charge of $100 or more if you take it to the shop
but less than $20 if you do it yourself.
The next point to check if the
engine still isn't running is the fire. The fire consists of
the coil (or magneto), the breaker points and the plug. A coil
will usually outlive the engine twice-over. The points and plug,
however, are a different story. They usually need replacing at
least one a year - call it an annual tune-up.
To check the points in the engine,
remove the plug wire. Hold it with insulated pliers about 1/4
inch from the end of the plug. Pull the rope starter. If the
points are breaking properly, you will be able to see the spark
as it jumps from the wire to the plug. If no fire is seen, replace
your points.
When you check the wire, there
might be a spark coming to the plug. If it is getting to the
plug, it is possible that it isn't getting through it. Remove
the plug from the engine. Put it back on the plug wire and pull
the rope starter. Be sure the plug is grounded against the engine.
If no fire is visible coming from the end of the plug, replace
the plug with a new one.
The small engine is popular all
over the world and will be with us for many years to come. You
would do well to learn to fix it. |
