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This instructable describes how to install the Speedway Instruments microTach+TM tachometer onto any 2004 or later Harley-Davidson motorcycle. For these model bikes the digital version of the microTach+TM tachometer is used. It operates exclusively on the J1850 VPW digital data bus signal used by Harley-Davidson.

See it in action:


Installation of the Speedway Instruments microTach+ TM Tachometer requires some basic
mechanical skills, including removing decorative covers, cutting protective tubing around wires, and
using suitcase splice connectors to splice existing wiring harness. These actions may void your warranty, and if done incorrectly may cause damage to your motorcycle. Only you know your capabilities, if you do not feel capable of making modification please have a qualified motorcycle technician install it.

Variations in location, color and procedure may be required for different year and make. Please refer to the Service manual to confirm the proper color and location of wires. Please make sure you have the proper service manual and tools before starting the installation.

In these instructions we will be splicing the tachometer into the wire harness behind the speedometer. There is an alternative installation available that uses the diagnostic connector which can be downloaded from the Speedway Instruments website or another instructable is coming soon.

Step 1 : Determine a mounting position. Each motorcycle is unique and the microTach+TM tachometer is small enough to be placed in many different locations to provide an attractive appearance and vital engine status. The pictures below illustrate a number of different stups which customers have done.

Once you have determined a good mounting place, go ahead and mount it. You may consider temporary mounting using Blue painters tape. But it is probably safe to go ahead and mount it permanantly.

Step 1: Find the Wires

Step 2: Remove trim around the speedometer inorder to access or determine the wire bundle which plugs into the back of the speedometer. The pictures illustrate a couple of different bikes.
1. Fatbob,
2. Sportster XLC
3. Nightster

Your bike is unique so take your time and take care to not scratch any paint.

Once you have identified the wire bundle, cut the protective tubing that surrounds the bundle to expose the individually colored wires. Make sure to expose enough wires to accomodate the 3 splice connectors in a staggered formation. Usually about 2.5" would be enough.

Step 2: Route Wires and Splice

Step 3: Determine a path for wires and route them. Hopefully you considered this as well when determining the mounting location. Take care that your routing is hidden as much as possible and if it is on the bars make sure you keep a bit of slack or service loop near the neck so that you can turn the bars in both directions without the wires being pulled tight.

Tip: Work from the tachometer toward the connection point securing the wires temporarily with painters tape along the way. This way you you can still move them if necessary or if your waiting til the later to slip the black sleeving over the wires.

Once wires are routed, cut them to length leaving a bit of working slack. Then cut the decorative braided sleeving to proper lenght and slip over the wires. Once the sleeving is on the wires you can proceed to secure the wires permanently using zip ties or whatever means you choose. It is best to start at the tachometer and work your way back to splice connection point.

Now splice the 3 tachometer wires onto the proper signal wires one at a time in a staggered pattern to make it easier to hide. Please note the difference in the ground wire color for different model years.

Step 3: Test and Clean-up

Step 4: Now is the time to test to make sure everything is working. Turn the key switch to accessory. The tachometer should display a "0" if you connected to the accessory power. If it doesn't light up, check the splice connections using a voltage detector or Digital Volt Meter(DVM). You can open the cover and probe for voltage on the metal part of the splice connector. Make sure there is approximately 12V between the Red and Black wires going to the tachometer. If not double check everything, including wire colors, proper seating of wires in splice connector, everything.

If you have the "0" lit, then go ahead and start the bike. The tachometer should read between 800 or "8" and 1200 or "12" RPM's It is likely going to bounce between 2 or 3 numbers when idling. Rev the engine a bit to make sure everything is working. If there is a problem with the reading check the white wire to make sure it is spliced through well.

Shut the bike off, and button up. If the splice connectors are going to be visible such as behind the headlight or near the neck, then it is best to wrap them up in electrical tape. The self-sealing kind is good. Wrap it nice and tight to keep as much moisture out as possible.

Put everything back together, if necessary use blue threadlock to make sure things stay back together.

Step 4: Ride It!

Now is the best part. Go for a nice long ride. But be careful not to stare at your new jewelry! Keep your eyes on the rode and just glance at it occasionally.

Use the tach to help you know when your in top gear and find the sweet spots for shifting.

Enjoy,

Justin Gaither
'''Speedway Instruments, LLC'''

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