Fouled Spark Plugs

How do you deal with a fouled spark plug in a dirt bike? The favorite answer is “buy a 4-stroke!” But that's not always an option – either because you love your 2-stroke and wouldn't trade it for anything, or you hate it and can't afford to replace it with anything.

The best way to deal with dirt bike spark plugs that are fouling is to keep them from getting fouled in the first place. So, before you do anything else, make sure your jetting is correct. The better the jetting, the less likely, or at least less often, you'll foul your spark plug.

Another preventative measure is to replace the spark plug in your dirt bike with a new one on a regular basis. How often? That depends on your riding schedule and habits. Use your past fouling history as a guide. If you typically end up with a fouled plug every couple of months, change the spark plug every month or six weeks.

What if you're out on the trail, or miles away from any handy spark plug provider, when your dirt bike stalls and won't start again? The easiest thing is to pull out the plug wrench and put in that spare spark plug you brought with you. You DID bring a wrench and spare plug, right?

Don't panic. If the only spark plug you have is the fouled one you just pulled out of your dirt bike, you still have options.

If you have a little kit you take with you riding, make sure it includes some fine emery cloth or a fine-grit sandpaper. If you don't have a kit, shove a piece in your pocket before you leave, or duct tape it to part of your bike. Use the sandpaper or emery cloth to clean the deposits off the business end of the spark plug. If possible, rinse the plug with a little bit of gasoline when you're done.

I've heard (one of those friend of a friend of a friend stories) that you can also grind a handful of sand in and around the plug to clean it. Sounds good in theory, but I haven't had the courage to give it a try. If you do attempt it, you'll definitely need to rinse it off with gas when done.

There's a good chance that you'll inadvertently adjust the gap when you clean your spark plug. Now, if you didn't pack a spare plug, you probably didn't bring along a gauge to set the gap with either. In that case, a credit card will usually work as a gauge – well enough to get you home, anyway.