How to Bypass CDI on ATV 750 

How to Bypass CDI on ATV 750 

The Capacitor Discharge Ignition box (CDI) is the heart of a bike. It produces the spark that ignites the engine. Without the CDI, the bike cannot run. 

If your ATV’s CDI has malfunctioned, there could be several reasons. First, you can bypass the CDI box to figure out the issue, but only temporarily. 

However, before you decide to bypass the black box, firstly, eliminate any other problems that could be possible.

Symptoms of a Malfunctioning ATV System 

Some tell-tale signs of a malfunctioning CDI are stalling engine, difficulty in ignition, bike running roughly, and misfiring. However, these can also be symptoms of a defective spark plug or fuel pump. So before you start checking your CDI, check these components:

  • First, test the bike’s main fuse. Also, remember always to keep a spare fuse in your kit. However, if it blows out constantly, there might be another issue.
  • Next, get a multimeter to test if the regulator effectively converts AC into DC. 
  • Next, get a voltmeter and check if your battery receives enough voltage. There might be other problems with your battery, like corrosion, loose bolts, and gaps in the connections.
  • Next, check if the stator is effectively powering the battery. Make sure to unplug it before checking the resistance and voltage. 
  • Finally, verify that all the wires are securely connected and working correctly.

Diagnose a Faulty CDI

CDI can be complicated to test. Therefore, all inputs connected to the CDI are checked for any faults or defects.

Bypass the Kill Switch

More often than not, bypassing the kill switch solves the problem, and the bike starts running again. 

To bypass a kill switch, you will have to remove the center pin or cut the wire from the connector. After disconnecting both, plug them back in and see if the engine starts. 

Test the Wiring

If the previous tip did not work, test the wiring. Use a test light to verify that the CDI receives enough ground voltage. 

Confirm the Timing Signal

If the CDI is functioning well, the magneto must be sending a timing signal. First, check to see if the signals are being received.

An ATV 750 will see a timing signal fluctuating between 0.2 and 0.4 VAC.

Test the Power Feed

The next step is to check if the CDI receives enough voltage and power feed. If it is functioning, then a CDI on an ATV 750 will receive a minimum of 50 VAC. Be careful while testing as the high voltage power feed can electrocute you.

If all the inputs are functioning correctly, the only solution is to replace your ATV CDI box.

Bypass the CDI

Now that you know that it is the defective CDI, you can bypass it to figure out the problem with the box. 

Here are the steps you should follow to bypass the ATV CDI box.

Empty The Tank

Make sure the motorcycle tank is empty of gasoline or other flammable liquids. Also, remember to confirm if the battery is 100 percent charged. Otherwise, change the battery before moving to the next step.

Remove The CDI 

Turn off the ATV and wait until the engine has cooled down. Then remove the CDI module. The CDI box is mainly placed under the rider’s seat. Remove it to access the electrical ports to measure resistances easily. 

If you are unsure about this step, refer to the owner manual.

Verify Resistance Values

The resistance values and specs are mentioned on the coil. The resistance specifications will differ for each ATV type. 

Use an ohmmeter to measure the primary resistance accurately. Then, touch the device to the external electrical terminals. 

To calculate the secondary coil resistance, touch one external and one internal electrical terminal.

These two readings should match the resistance specified on the coil. However, if the coil is damaged, the measured resistance values will not match the values mentioned on the coil. In this case, the CDI will have to be replaced immediately.

Conclusion

An optimal functioning CDI module will offer you a smooth and thrilling ATV ride. However, since the CDI is such an essential and sensitive bike component, it requires regular maintenance. 

As an amateur, you might not know all the work involved in taking care of the ATV 750. Fortunately, Yapq provides all the news on the great outdoors. In addition, several articles on the website may help you learn everything about mountain biking and your ATV bike. 

In addition, being on top of the maintenance work will save you from any unexpected expenses that may cause a dent in your budget.