How do you know which type of ignition system your Honda CX or GL has – CDI or TI? There’s a few ways to tell – check them out below. First, though, here’s a rough table of what to expect:
| Year | Model | Came from the factory with (generally etc.) |
|---|---|---|
| 1978-1981 | CX500 | CDI |
| 1982 | CX500 Custom (USA) CX500 Shadow (AU) | TI |
| 1981-1982 | GL500 | TI |
| 1983 | GL650, CX650C, CX650E | TI |
Given that some of these bikes are approaching 40 years old it’s not terribly surprising that some engine swaps have occured over time; if in doubt, check! As for how to check, let’s look at the differences between the two systems that you can see without opening up the motor.
CDI components, external to engine
The CDI box should be underneath the seat on your CX500 – it can be black or gold. This particular one used to be black before it got a bit rusty:
As far as external signs that the motor is CDI goes, the rear plate should look like this:
TI components, external to engine
Depending on which model you have, your ignition boxes may be underneath your seat or underneath one of the side covers of your motorcycle. There should be two little silver boxes with “NEC” on them:
As far as external signs that a motor is TI goes, the rear pulser cover should look like this – complete with crankcase vent hose coming from it (image upper right) and going to the airbox. It’s thicker than the CDI rear cover section – when we can we will get a side-on photo as well.
Now for the differences in terms of engine internals.
CDI components, engine internal
The CDI system uses coils on the stator to power the ignition system directly; they are part of the stator which is attached to the rear cover, and on the stock stator they are the two bulkier looking coils looking like so:
One of the bulky coils is the high speed coil, one the low speed coil. These bigger coils are part of the reason why the CDI CX500 can be bump started and run with a completely flat battery or even without a battery present; the ignition system is powered by these coils directly rather than by the 12V electrical system. Speaking of the electrical system, the charging coils are more plentiful and are smaller:
The high speed and low speed pickups are situated in the rear cover and are above the stator, one pair on either side:
They are marked left and right. Note that “left” here means left as if you were sitting on the seat; it’s going to be on the right hand side if you’re looking at it from the front.
The advance pickups are located on the very back of the rear engine cover under the little plate:
Apart from the charging coils none of the above are present on a TI motor! If you move your ignition system over to an aftermarket system like a Rae-san unit or an Ignitech you will be eliminating some (or all) of the old ignition components at the cost of losing the ability to run the bike with a completely flat battery (presuming that your ignition system is otherwise working).
TI components, engine internal
The pulse generators sit in the rear engine cover, under the little plate at the back:
This apparatus – and the rotor mechanism in the middle of it – combine the function of the CDI’s internal high and low speed pickups and advance pulser unit into one location. The little rotor in the middle passes pickups in the pulse generator and the advance mechanism is mechanical – there are springs behind the rotor:
The stator on the TI system should consist of eighteen windings, all of which are the same size:
Here’s the advance rotor, out of the motor:
And the side of the pickups, out of the motor:
If you’re wondering which of the above components are required for the various aftermarket ignition setup options, check out this page here.