cdi no spark

[hoppy41]

Hello. Has anyone replaced the cdi ? My bike is a 1992 model. have a no spark problem .
Will any other cdi units work ?

[Allrover]

Hi, I replaced the CDI last week as my rev counter wasn't working. It's a really easy things to do - I picked a replacement up from a breakers yard selling via eBay for about fourty quid. Fitting it is as simple as removing the petrol tank, & undoing the one screw that holds the CDI in place. Then unclip the CDI from the wiring loom, and plug in the new one. Its just one big socket, can't go wrong.

Obviously without more details on the nature of your problem I cant say if it will fix it mind you, but if you want to swap out the CDI, then thats how to do it.

[hoppy41]

Hi. Thanks for input.

My bike 92 cb400sf was running fine. Now it turns over, ignition lights are on. But I have no spark at any of plugs.
Fuse is ok. Cdi has power going to it.
Surely both coils cant be dead? Getting some strange multimeter Readng for coils. Supposed to be 2-4 ohms but mine are way over that

I thinks the cdi is bust.

Any thoughts ?

Dave

[hoppy41]

Your bike still ran though .? Mines dead as a do do

[Kenbob999]

Hi guys,

I'm in the process of ordering a new one too.
Only because my headlight isn't working and there's no switch, so I've been told that the headlight relay (see my previous post) is controlled by this CDI unit. I've had mine off and cleaned the terminals, that didn't work and I've replaced the loom.
Basically have 100% new electrics on my bike. Any ideas lads?

[SevenThreeSeven]

My bike 92 cb400sf was running fine. Now it turns over, ignition lights are on. But I have no spark at any of plugs.
Fuse is ok. Cdi has power going to it. Surely both coils cant be dead?

All of this happening suddenly and all at once sounds like it could be a pulse generator issue. There's a toothed wheel (a.k.a trigger wheel) attached to the bike's crankshaft (under the engine's left side crankcase cover) and there's a Variable Reluctance sensor (a.k.a the pulse generator) placed near it. As the teeth of the toothed wheel pass by the pulse generator it sends an analog signal to the Ignition Control Box (a.k.a the CDI). Without this signal the Ignition Control Box will not fire either of the coils.

The pulse generator has two wires, both of which are routed to the Ignition Control Box.

The pulse generator itself is a very robust item, so I'm betting there's no problem there. There could be a problem with the wiring that connects it to the Ignition Control Box. The pulse generator's two wires emerge from the top of the engine's left side cover in a sheathing and this proceeds to a two-pin connector plug which then links the two wires into the bike's overall wiring harness, which eventually leads to the multi-pin connector plug at the Ignition Control Box.

Getting some strange multimeter Readng for coils. Supposed to be 2-4 ohms but mine are way over that

Are you measuring correctly? The coil has two windings inside it, a primary winding and a secondary winding. The Ohms of the primary winding are measured by probing the two small-wire leads, and the Ohm reading should be 2-4. The secondary winding is the measured by probing the positive small-wire lead and the high-tension output to the spark plug. It should show an Ohms reading at least 10 times that of the primary winding.

(edit: I just looked at the SuperFour maintenance manual and I see that Honda directs you to check the coil's secondary winding by probing the coil's two high-tension output leads. The acceptable reading for probing the two high-tension leads, with the spark plug boots still in place, is 23-27 kOhm. So you'll need to insure that your multimeter is set to an Ohm setting that can correctly interpret this level resistance.)

[hoppy41]

thanks for help, ordered a replacement cdi box and a new multimeter!

Ill report how I get on.

:-)

Dave

[hoppy41]

The new replacement cdi Ive got on order states as follows:

'This series of digital ignition coil, breaking the analog control of the traditional method'

its some sort of replacement from China, wonder if it doesnt need pulse generator then?

[SevenThreeSeven]

The new replacement cdi Ive got on order states as follows:

'This series of digital ignition coil, breaking the analog control of the traditional method'

its some sort of replacement from China, wonder if it doesnt need pulse generator then?

Nothing like Chinese-to-English translation done by a native Chinese speaker rather than by a native English speaker. More often than not it seems to come out as gibberish...

I didn't mean to confuse your situation so I'll try to further clarify. First, there absolutely has to be a signal from the bike's crankshaft.

I'm not sure what that quote about the replacement CDI means (or what it is intended to tell you).

As originally configured, your SuperFour uses a Variable Reluctance sensor (pulse generator) that delivers an analog signal to the CDI.

This is a generic representation of what is going on:

That "wave form" output signal you see is an analog signal. Here's what it looks like on an Oscilloscope:

This analog signal from the SuperFour's Variable Reluctance sensor is the only "analog" thing in the system. The SuperFour's CDI takes this analog input and converts it to a stream of "digital" data (basically a stream of digital data that indicates either "on" as a tooth on the toothed wheel passes the sensor and "off" in between the teeth).


The only way to remove the necessity for this analog-to-digital conversion by the CDI would be to replace the Variable Reluctance sensor with a "Hall Effect" sensor. The Hall Effect sensor produces digital data from the Toothed Wheel in the form of a electrical signal that is either 5volts or 0volts.


I'm pretty sure that there's not a sensor change included along with the replacement Chinese-made CDI you've ordered. This replacement CDI is almost certainly intended to be simply a "remove and replace" situation with no change to any of the other components in the SuperFour's ignition system or electrical system.

I'm still saying that you need to check/test/inspect your SuperFour's Variable Reluctance sensor wiring, from the engine's left side case to the plug that connects it to the bike's wiring harness and from there to the CDI multi-pin plug.

[hoppy41]

thanks for excellent help, investigating pulse generator wires.

thanks

dave