Here’s how to check and adjust the air gap in the transistorised ignition (TI) equipped Honda CX400, CX500, CX650, GL400, GL500, GL650 and GL700 motorcycles. It’s an important step in ensuring that your ignition system is set up correctly.
For this you will need a set of feeler gauges and if you need to modify the air gap, a screwdriver.
The air gap we are looking for is between 0.45mm and 0.65mm (0.018 – 0.026″).
Rotate your crankshaft using the 17mm bolt on the front until the rotor tooth is directly over the pickup:
Grab your feeler gauges – wipe them clean to ensure that no metal shavings are going to be introduced – and verify that the air gap is between 0.45 and 0.65mm. In other words, the gap should allow at least a 0.45mm feeler gauge through but not allow anything thicker than a 0.65mm feeler gauge.
If it’s out – like this one below, where you can see that the gap is notably more than the 0.65mm feeler gauge inserted:
Loosen the three screws to adjust the gap and re-check until it’s correct:
…and you’re done. If you’re doing this as part of the static timing check + assessment click here to go back to the main page for that.