Unlike contemporary dirt bikes, many older dirt bikes did not have an ignition key. The bike was ready to go at all times and kicking it over activated the electrical circuit from the battery. Installing an ignition key can upgrade a dirt bike and provide some protection against theft or a child starting the bike. Motorcycle ignition switches are available through a number of sources and can be adapted to most dirt bikes. Metal tubing and insulated wire complete a short parts list.
Measure the outside diameter of the motorcycle ignition switch. Select a piece of metal tubing with an inside diameter that will sleeve the switch securely. Use a hacksaw and cut the tubing to a length that will house the ignition and cover the wire connection terminals. Smooth the cut end of the tubing sleeve with a flat file.
Position the sleeve on the motorcycle frame at the desired location. Prep the section of the frame with the flat file to remove any paint. Use a soldering tool and steel solder to attach the sleeve to the frame. Allow the solder to cool completely.
Disconnect the positive and negative wire leads from the battery. Use the wire strippers to remove a 1-inch section of the insulation about 2 inches from the end of each lead. Cut two strands of number 14 insulated wire that reach from the ignition sleeve to the battery and bare the ends of each strand with the wire strippers.
Slide a crimp connector on the end of one of the strands of wire and crimp the connector with the wire strippers. Bend one of the battery leads at the exposed section of bare wire to form a point.
Insert the point of bare wire into the open end of the crimp connector and secure the attachment with the wire strippers. Repeat this with the other battery lead and remaining strand of wire. Do not reattach the battery leads to the battery at this point.
String the wire leads from the battery leads to the ignition sleeve and insert them from behind. Connect the leads to the motorcycle ignition switch. Put a rubber O-ring around the top rim of the motorcycle ignition switch.
Push the ignition switch into the metal sleeve. If necessary, wet the o-ring with water so it pushes into the sleeve. Do not use lubricant or the switch will not remain secure. Cut a length of split wire shield and encase the wire leads from the switch to the battery leads.
Wrap the crimp connectors on the battery leads with electrical tape. Attach the positive and negative leads to the battery. Insert the key into the ignition switch, turn it to the on position and start the dirt bike.
Use additional o-rings or wrap the switch with electrical tape or a secure installation. Use silicone to waterproof the back end of the switch.