Signal Mirrors Size Guide
Signal mirror sizes differ; some are 2"x3", 3"x5", 2”x 4” and other sizes. 
Some signal mirrors can also be custom fitted to a specific vehicle. If you are going to get one for your motorcycle, the following information may prove useful.
Preparatory Steps
The first step is to ensure you have the manual for your bike. You will need to get familiar with the basic layout of the bike. Make sure you are familiar with the front turn signals wiring areas. Make sure you understand the removal process before proceeding.
Installing the Signal Mirror on Motorcycles
These instructions will work regardless of the signal mirror size. However, you may want to check the manual if there are specific ways of installing it.
Unscrew the acorn nut on the clutch lever pouches and the brake’s underside. Twist the mirror in a counterclockwise manner. If the motorcycle employs the stud and ball type clamp, loosen the ball clamp. Do this by spinning it in a counterclockwise manner. Take out the mirror.
Adding the Mirrors
Get the new mirrors and install them on the brake lever perches and clutch. Put the power wire leads into the perch. Now you have to twist the mirror in a clockwise manner.
Keep doing this until it sits against the perch. Next, connect the ground terminal in an upward manner. Fasten the mirror by implementing the washers and the lock nut or acorn.
Wiring the Turn Signals
Find the motorcycle wiring harness. You will need to refer to the motorcycle manual for this information. This will vary per model. For example, some motorcycles have their harness concealed in the headlight casing.
There are also large bikes which fasten the wiring harness in the front fairing. After you have located the harness, mark out the wiring from the turn signals to the harness. This will help you find all the signal connectors.
Unhook the original signals and connect the signal mirror wiring Y harness. Trace the harness to the bike handlebars. Hook the initial connector on the Y harness. If you want, the original turn signal may still be used. You just have to connect them onto the other connector. This is at the wiring Y harness.
No matter what the signal mirror size is, installation should be a straightforward process. As long as you have your bike manual, there should be little problems. You just need to be patient during the whole process.
