One of the easiest tune up parts you can easily replace at home is to replace your old worn out spark plugs. You will need a 10mm socket to remove the four black (or possible rusted) nuts holding on that L shaped black cover. Once the cover is removed move on to removing the next four 10mm bolts holding down the coil on plugs. Then slide an extension with a socket socket down the holes and remove the old spark plugs. This is a good time to see if the spark plugs are telling you about the condition of your motor. You should only buy NGK spark plugs, don’t skimp out on the cheap ones.