CMS-Japanese Motorcycle Supply Parts

How to check and test the pulse generators on a TI Honda CX500, GL500, CX650, GL650


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Here is how to check the resistance of the pulse generators - also referred to as the timing pickups - on a Honda CX500, GL500, CX650, GL650, GL700, CX400 or GL400 motorcycle. This is only applicable to those vehicles equipped with the transistorised ignition (TI) - CDI bikes ('78-81 CX500s) do not have these components. For this you need a multimeter! Find the end of the wires coming from the pulse generators and emerging from the pickup cover - if you're doing a triple or quadruple bypass they'll be easy to find at the back of the motor:

Here's how to check the advance timing pickups on a TI Honda CX500, GL500, CX650, GL650 by measuring their resistance with a multimeter.

Set your multimeter to the 2K Ohms setting:

Here's how to check the advance timing pickups on a TI Honda CX500, GL500, CX650, GL650 by measuring their resistance with a multimeter.

The wires are in pairs; one side is blue and blue with a white collar:

Here's how to check the advance timing pickups on a TI Honda CX500, GL500, CX650, GL650 by measuring their resistance with a multimeter.

The other side is yellow (by now - 30 years on - a dirty white...) and yellow with a white collar:

Here's how to check the advance timing pickups on a TI Honda CX500, GL500, CX650, GL650 by measuring their resistance with a multimeter.

Measure between each of the above pairs using your multimeter:

Here's how to check the advance timing pickups on a TI Honda CX500, GL500, CX650, GL650 by measuring their resistance with a multimeter.

The resistance reading you are ideally looking for is 530ohms. The acceptable range is 480 to 580 - e.g. within 50 Ohms or about 10% of the ideal figure. In this case both left and right sides were very close to ideal:

Here's how to check the advance timing pickups on a TI Honda CX500, GL500, CX650, GL650 by measuring their resistance with a multimeter.

Here's how to check the advance timing pickups on a TI Honda CX500, GL500, CX650, GL650 by measuring their resistance with a multimeter.

Now set your multimeter to the "continuity" setting and check - one at a time - that all four leads have zero continuity to ground. You can have a pickup coil which has the correct resistance but shunts the trigger current to ground, resulting in no spark on that side - so worth checking.

If you're just checking the pickups you're all done, but if you're reassembling and doing static timing check procedure + assessment click here to go back to the main page for that.



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