How many of us can honestly say that we give much thought to the sparkplug quietly sitting within our ATV?  It was common practice to think about bringing spare plugs back in the 2-stroke days but thanks to the increased reliability of the four-stroke, it’s pretty easy to forget all about them.

Here’s the kicker, the spark plug’s role in the internal combustion process makes it every bit as important as say the piston, cylinder or gasoline.  And like most internal engine components, it does wear out.

The fastidious mechanic would recommend pulling out your plug and giving it a good look over every six hours of operation but we (guilty admit) have gone as long as ten hours before remembering to do so.

The first area to be concerned with is just above the head’s threads (where the plug’s metal washers nestle up when being installed) as this divot has a tendency to collect and hold water.  If you hear a crunching sound when you first begin to loosen the plug, it’s a good bet you’ve got corrosion taking place in this area.  Grab a damp rag and gently wrap it around the plug’s threads as you are unscrewing it so as not to knock any loose debris or water into the engine.

Now that you have the plug removed, check the electrode.  If it is black with carbon residue or wet with oily gasoline deposits, your best bet is to simply toss it and replace with a fresh plug.  However for many of us the decision to inspect your plug happens to take place in the middle of the night when you don’t have a spare on hand.  In those instances it is possible to attempt to give the electrode a good cleaning then to reinstall the plug until you can pick up a new one.

In that case gently remove carbon deposits with steel wool or a very fine grit sand paper.  The idea is to make visible the shiny metal of the center electrode (where it emerges from the porcelain body) and the ground electrode (the external hooked metal at the very bottom).

If on the other hand your plug is wet or oily, the plan is to dry it up as thoroughly as possible.  We recommend using a quick drying solvent like automotive brake cleaner or electrical contact cleaner.  Afterward (or if it is your only option), use a clean shop rag or towel to remove any additional moisture on the center and ground electrode.

If done correctly, this should sneak a little extra life from a tired spark plug however if the plug has fouled to the point where the machine simply wouldn’t start or run before you took it out, odds are good that the only option is to pitch it and buy a new one.

Tip: Even if the plug is fouled beyond resuscitation, write down the code then screw the plug back into the engine while you shop for its replacement.  Taking the plug out leaves the head open to all sorts of contamination.

Another sign for immediate replacement is a corroded or pitted electrode.  The flow of electricity is greatly hampered by metal in such condition.

So now you’ve got a new plug (and hopefully remembered to pick up a spare or two in the process), don’t go crank it in and blast off.  Take a few moments to refer to two key areas in your owner’s manual (which are probably available online or by calling your dealer if you don’t have the manual for your machine:  

1)      Set the gap.  A 99-cent gapping tool available at nearly any auto parts store in the country should be adequate. Proper gap insures optimal heat generation to ignite the air-fuel mixture.

2)      Check the proper torque.  Over tightening the spark plug can be very damaging to the threads within the head.  Likewise under tightening can cause the plug to work its way free or to lose contact with the combustion chamber.  

A few minutes worth of work can make all the difference in the world and besides, even a still-functioning plug that isn’t providing your machine with the hottest, cleanest spark possible means that you are sacrificing engine performance.