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Acewell 3901/3903/3913/3915

Acewell 3100 series

Here is a great add on project for anyone without a working speedometer.

This Acewell brand speedometer (available from ILLOWA CYCLE starting at $119.99 + shipping) is a great value, and is an easily installed option. It offers a digital speedo, tach, odometer, a maximum speed record, 2 trip odometers, a timer, a clock, and it cures male pattern baldness! Just kidding about that last one, but seriously this is one powerful instrument. Installation consist of dealing with just 6 wires. The unit must be grounded and then hooked to battery constant 12 volts, switched ignition 12 volts. There is one wire to connect to the ignition system for the tach signal and another pigtail with a magnetic sensor on the end of it. The speed signal is generated by a magnetic bolt that is hooked to the wheel or brake rotor that then passes the small magnetic sensor, which is then used to calculate the speed and odometer mileage.

Here’a photo of the speedometer mounted on Moby Dick. This photo shows the display is already connected and working, but the installation is not complete at this point.

I decided to mount the speed sensor to the rear wheel because it looked to be the sturdiest option. Above you can see the fresh hole that I drilled for the magnet to mount to the wheel. Below is the magnetic bolt already installed in the hole.

To calibrate the unit to the individual machine you must measure the tire circumference. My favorite method of doing this is to wrap a piece of masking tape around the wheel and mark it where the ends overlap.

Once this is done remove the tape and lay it out on the floor and then measure between the marks you made on the tape. In this case the reading was 2085 millimeters.

Harry get your feet out of my photo!

I still need to hook the tachometer wire up and mount the sensor on the driveshaft housing near the magnet and program the unit and the installation will be complete. Here is a photo that shows the cool blue backlight.

Send any comments to Brad.