How to Wire a Motorcycle Tachometer

Installing a tachometer on your motorcycle can be a great way to monitor your engine’s revolutions per minute (RPMs), ensuring you don’t over-rev the engine. A tachometer allows you to shift at optimal times for performance and engine life.

Wiring a tachometer is not overly complex, but does require attention to detail. In this comprehensive guide, we’ll walk through the complete process of installing and wiring an aftermarket tachometer on your motorcycle.

Benefits of Adding a Tachometer

Here are some of the key benefits of installing a tachometer on your motorcycle:

  • Prevent Over-Revving: The tachometer displays your engine RPMs, allowing you to avoid exceeding the redline and potentially damaging internal engine components.
  • Optimize Shifting: Keeping an eye on the tachometer allows you to shift at ideal RPMs for maximum performance and engine life.
  • Monitor Engine Load: Watching the tachometer can give you a sense of how hard you’re working the engine in different riding scenarios.
  • Troubleshoot Problems: Unusual tachometer readings can indicate potential issues like ignition or valve train problems.
  • Improve Safety: Keeping RPMs in check can prevent loss of control from abrupt power changes.

Tachometer Styles

There are a few main types of tachometers to consider:

  • Analog: The classic style with a physical needle that sweeps an arc to indicate RPMs. Easy to view at a glance.
  • Digital: Displays a numeric RPM reading, often with shift light indicators. Easier to get precise readout.
  • Combo Units: Combine analog and digital displays in one gauge for best of both worlds.
  • Dedicated Units: Display only the tachometer function. Good for minimalism.
  • Multi-Function: Integrate tachometer into unit with speedometer, odometer, etc. More info in one place.

Choose the style that best fits your motorcycle setup and visual preferences.

Wiring Overview

We’ll be covering complete step-by-step wiring instructions, but here is an overview of the process:

  • Mount the tachometer securely on the motorcycle.
  • Run power wires from the battery to the gauge.
  • Connect a signal wire from the tach to the ignition coil.
  • Ground the tachometer wires to chassis.
  • Connect illumination wires if needed.
  • Start motorcycle and calibrate the tachometer.
  • Test operation and make any adjustments.

Proper connections and wire routing are critical, so we’ll go through each step in detail.

Step 1: Mount the Tachometer

The first step is finding a suitable mounting location for the tachometer on your motorcycle. Some options to consider:

  • Handlebar mounts: Great visibility while riding. Ensure wires don’t interfere with controls.
  • Fork stem mounts: Also very visible. Make sure wires don’t bind when turning.
  • Frame mounts: Useful for minimalist looks. May need to glance down more.
  • Combination gauge mounts: If adding tachometer to existing cluster.
  • Custom fabricated brackets: For unique mounting solutions.

You’ll need to measure carefully and select the proper diameter clamp for the bars or location you select. The tachometer should be oriented so it’s easy to read when riding.

Once you’ve determined the ideal mounting spot, secure the tachometer tightly using the manufacturer supplied hardware. Don’t fully tighten yet in case you need to adjust the angle.

Step 2: Run Power Supply Wires

The tachometer will require a 12 volt power source to operate. This is typically run directly from the motorcycle’s battery.

Here is the process for running power wires:

  • Cut a length of 16 or 18 AWG wire long enough to reach from the tachometer to the battery area. Red is positive, black is negative.
  • Run the wire along the frame, securing it neatly with zip ties. Avoid any hot or moving parts.
  • Install an automotive grade fuse holder with a 1 amp fuse inline on the positive wire for safety.
  • Connect the positive (red) wire to the positive battery terminal, or any 12V+ connection that is live when ignition is on.
  • Connect the negative (black) wire to the negative battery terminal or a grounding point on the motorcycle frame.
  • Connect the power wires to the corresponding terminals on the tachometer. Consult the manufacturer diagram.
  • Seal any wire connections with heat shrink tubing or electrical tape.

With the 12V+ and ground connections made, the tachometer will have power. But it still needs the engine signal to operate.

Step 3: Connect Signal Wire to Ignition Coil

The tachometer determines engine RPMs based on electrical pulses from the ignition system. This signal wire connects to the negative side of the coil.

Follow this procedure to connect the signal wire properly:

  • Locate the negative coil terminal. Consult a service manual for your motorcycle if needed.
  • Cut a length of 18 or 20 AWG wire to reach from there to the tachometer.
  • Use a spade terminal to connect to the negative post on the coil.
  • Route the wire neatly along the frame with zip ties and avoid any hot or moving parts.
  • Connect the other end to the signal input on the tachometer. Consult the wiring diagram.
  • Make sure the connection is clean and tight. Seal with electrical tape.

The tachometer can now read the engine RPM signal from the coil and display it on the gauge.

Step 4: Ground the Tachometer

For proper operation, the tachometer itself must be electrically grounded to the motorcycle frame.

  • Cut an appropriate length of 16 or 18 AWG black wire.
  • Connect one end to the ground terminal on the tachometer. Consult the wiring diagram.
  • Connect the other end to a suitable grounding point on the metal frame of the motorcycle.
  • Make sure this completes the ground circuit with a good chassis connection.
  • Seal and secure all ground wire connections to prevent issues.

Step 5: Connect Illumination Wiring (If Equipped)

If your tachometer has built-in lighting for night visibility, wiring the illumination is the final electrical step.

  • Run a wire from the lighting power source to the gauge illumination input. Can tap into headlight or marker light power.
  • Connect the other wire end to the illumination feed on the tach. Verify polarity.
  • Ground the other illumination wire as shown in the diagram.
  • Testing the headlight or marker lights should make the gauge light up.

That completes the basic electrical wiring of the tachometer. Now it’s time for calibration and testing.

Step 6: Calibrate the Tachometer Reading

With everything wired up, the tachometer should be powered on and reading engine RPMs. But the reading may not be accurate yet without calibration.

Here is how to calibrate:

  • With engine off, turn ignition on so tachometer powers up.
  • Start engine and compare actual RPMs to tachometer reading. Verify with service manual specs.
  • If reading is off, consult tachometer instructions for calibration procedure. Often there is a potentiometer that can tweak the signal.
  • Rev engine and adjust until tachometer readout matches actual RPMs.
  • Confirm accurate readings across low, mid, and high RPM ranges.
  • Re-check calibration and make adjustments as needed if the tachometer is off.

Step 7: Test Tachometer Operation

Once installation is complete, thoroughly test operation of the tachometer before considering the job done.

  • Turn ignition on and off to verify proper power up and down behavior.
  • Start engine and rev through entire RPM range while observing tachometer.
  • Readings should be smooth and consistent with no jumps or drops.
  • Allow engine to warm up and re-check calibration. Adjust if needed.
  • Visually inspect all wiring connections for security.
  • Take a test ride while frequently checking the tachometer function.
  • Make final mounting angle adjustments if visibility needs improvement.
  • Confirm no wires are binding or chafing during full lock steering.

If everything checks out, the tachometer is fully installed and ready to monitor RPMs on the road!

Troubleshooting Tachometer Issues

If your newly installed tachometer is not working properly, here are some troubleshooting tips:

  • No power – Check fuse, connections to battery, ground wire.
  • No reading – Verify coil signal wire connection.
  • Reading stuck at 0 – Check for loose ground or signal connections.
  • Reading inaccurate – Re-calibrate, check signal wire routing.
  • Reading erratic – Could be loose wire, defective gauge, or bad coil signal.
  • Dim or no illumination – Check wiring from lights, ground connection.

Carefully inspect all wiring and connections to identify the cause of any issues. Also consult the tachometer manufacturer troubleshooting guidance.

Tachometer Installation Tips

Here are some additional tips to ensure your tachometer installation goes smoothly:

  • Use quality wire, terminals, connectors to avoid issues.
  • Follow wiring diagram precisely, double checking connections.
  • Route and secure wires neatly to prevent hazards.
  • Seal connections properly to avoid corrosion.
  • Confirm suitable tachometer signal from coil before wiring.
  • Use extreme caution working around battery, fuel sources.
  • Double check orientation for ideal visibility.
  • Verify clearance for any steering and suspension movement.

Taking it slow and methodically following each wiring step is key to a successful installation.

Conclusion

Adding a tachometer to your motorcycle is a great upgrade that provides valuable performance and engine monitoring capabilities. With some mechanical aptitude and basic electrical knowledge, wiring a tachometer is a very achievable DIY project. Just take it step-by-step.

This guide has walked through the complete installation process, from selecting the right tachometer to troubleshooting any issues. Follow the wiring diagrams precisely, make good connections, route wires neatly, and double check your work. Before you know it, you’ll be able to keep an eye on engine RPMs right on your handlebars. Ride safe!

Key Takeaways:

  • A tachometer allows you to monitor RPMs to prevent over-revving and optimize shifting.
  • Mount the tachometer securely in an optimal visible location on the motorcycle.
  • Run 12V power wires directly from the battery to the tachometer.
  • Connect the tach signal wire to the negative terminal of the ignition coil.
  • Make sure to ground the tach wires properly to the chassis.
  • Calibrate the tachometer reading with a known RPM source.
  • Carefully test all functions before riding with the newly installed tachometer.

Citations: [1] https://asset.lemansnet.com/gen/partssource/prod/90000/94800/94807_V1.pdf [2] https://www.atsunday.com/2014/06/wiring-diagram-for-aftermarket.html?m=1 [3] https://www.ehow.co.uk/how_5963031_wire-motorcycle-tachometer.html [4] https://youtube.com/watch?v=Ii4_8eN3wBg [5] https://www.jegs.com/tech-articles/step-by-step-instructions-for-how-to-install-a-tachometer/ [6] https://www.tw200forum.com/threads/analog-tachometer-install.69501/

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