Tuning up the engine on your 4-wheeler is easier if you know what those spark plugs are telling you. You can tell a lot about your the health of your engine just be looking a the spark plugs. There are five basic colors to know and conditions associated with them.
Grey mean that your engine is running good on all points. Nothing is building up and your plugs are burning properly.
Black(but looks dry) Your carburetor may be set to high and your plugs are not burning as they should. Your flame arrestor may be set incorrectly or merely need cleaning. Weak sparks may be leaving the blackening on your plugs so check the ignition system of your 4-wheeler too.
Black(but looks wet) Your oil and gas are not mixing properly and both should be checked. You could have a condensation problem or merely have "bad" oil or gasoline in your machine. This is probably true if you are noticing a lumpy type of build up starting to happen around the plugs as described below.
Chalky,(lumpy build up) may indicate bad fuel or an oil problem. Always be sure you are using the right grade of oil according to the owners manual. If you can rule this problem out, you might want to look for an oil leak in the combustion chamber.
White, with bubbles or blistering, your plugs are overheating. This could be caused by a gapping or torque problem, as well as an air and fuel mix set too lean. If you can rule these problems out, check your timing, as too fast will cause your spark plugs to burn too hot.
By knowing how to read your spark plug colors, you can catch problems developing early before they do more serious damage to your engine on your 4-wheeler.
