TROUBLESHOOTING ONE-CYLINDER

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.

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 withe 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!

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 troddle 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.