How to Change Motorcycle Spark Plugs

How to Change Motorcycle Spark Plugs
Hello! This is Jerry Fishel from Vicious Cycles in Santa Clara, Utah for Expert Village. We are going to talk about at this point and time is spark plugs. How to change spark plugs, how to know when if your bike is running too rich or running too lean. So let’s take our spark plugs. Harley Davidson’s have two spark plugs: one in the front and one in the rear, one for each cylinder. What I have here is just a regular ratchet wrench and a plug socket. This socket has a rubber grommet inside of it to hold on to the plug and pull it out for you. What you want to notice on your spark plug is the coloring of your plug. This plug is running just about perfect: slightly tan brown around the ceramic diode. If your plug is black or a furry black around this, your bike is running too rich. If it is a white powdery color, then your bike is running too lean. Change your spark plugs every 5 to 10,000 miles, depending if your bike starts to miss, misfire or run kind of sluggish, check your plugs first. Correct plug gap should be between 38,000 of an inch and 42,000 of an inch. I use a wire gaper to gap the plug. There are other types of gapers. There is a slide gaper, slide type gaper. I prefer the wire gaper because I feel it is more accurate. This plug is fine. This front plug you can tell is running a little bit rich on the front cylinder because it is a light black color, and actually it is slightly wet. We are running a little bit rich in our front cylinder. You will get variances between cylinders. As long as it is not missing and running fine, you should be just fine. This plug is still a good plug and looks like it will run just fine. Once you re-install your plug snuggly into this cylinder, take your spark plug boot, stick it over the plug and listen for the click. You should be able to hear it click when you are pushing on. One thing to remember about Harley Davidson’s it is best to use the stock type plug made by Harley Davidson and the stock type wires, because with the Harley Davidson in fuel injection system, there is a carrier wave that runs across the spark plug, through the spark plug and through the coil wire that does ion sensing that senses the amount of burn inside of the cylinder. If you don’t use the correct plug with the correct ohms resistance, because it reads the resistance in the wire, the bike will have misreadings and sometimes can misfire or run sluggishly. So I suggest always using the stock spark plugs and spark plug wires.