Honda CX and GL Ignition Systems

The Honda CX500 ran two different types of ignition system over the course of it's production run; CDI and TI. The GLs and 650s featured TI - for more information on all of the systems check out our articles below!

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The twisted twins use one of two forms of ignition; capacitive discharge or transistorised. You will typically see these abbreviated as CDI or TI. All 650s, all GL models and some later (sometime in '81 onwards in some markets, others '82) are TI, whereas all other CX500s are CDI.

Both systems are a waste spark system (Why? See here).

How do you tell which system you have? Click here to see the differences and how to tell.

The CDI system

The CDI system requires additional components in and around the stator; as such there's more to go wrong internally, but the CDI system has the notable advantage of not requiring a functional battery to run. If you can bump-start your bike it will run, even with a dead battery. One point of note - it has been suggested that the CDI box might be damaged by running with a spark plug cap left ungrounded, as might happen if you were to pull one spark plug cap with a running engine as part of a diagnostic test. To avoid this, you could ground the spark plug cap prior to starting the bike - if you are concerned.

The CDI setup looks like a small black box underneath your seat, pictured above.

Alternatives to the CDI box

Which ignition system components do you need to keep for the aftermarket options?


By far the most popular aftermarket CDI alternative is the Ignitech.

Finnbox CDI

Aki Lötjönen has produced a CDI alternative called the Finnbox G47.

Click here for a closer look at the Finnbox.


Australian company Rae-San has a CDI alternative in the works which utilises the Hall effect, removing the need for the CDI pickups.

Here's an example of the Rae San CX/GL kit

The TI system

The TI system does not need the additional internal componentry and as such the stator is a charge-only unit. If you have the TI setup you will see two little silver boxes under the seat or side cover, pictured above. All 650s, all GL500s and some later CX500s in some countries have the TI system.

Ignition Coils

The ideal ohm range for a of TI coil - useful to know when you have to replace them with non-original units - is 2.5 to 5.0ohms, according to Rayman of Rae-San.

Ignition Leads

On CDI bikes these are built in to the ignition coil, so you can't replace them separately - unless you use something like the NGK wire splicer.

Spark Plug Caps

These sit between the spark plug leads and the spark plug. There are two types - resistor caps and non-resistor caps. The resistor caps should have a resistance of 5K Ohms, and the non-resistor caps should have zero resistance.

Spark Plugs

Missing Timing Indicator

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