CBX 250 RSE no spark

[Orcade-Ian]

I've had a grotty looking CBX 250 RSE for a good few years - unloved in a far corner of the shed. In a moment of madness I cleared the bike bench and put it on.  I knew it didn't have a spark right from first getting it but too many other jobs intervened.  It has the radial four valve DOHC unit, like an XBR or GB 250/400/500 but with 2 carbs on a single pot with twin exhausts.
There is some kind of 'exciter' or igniter behind the r/h engine cover with two wires.  They read open circuit between the two wires.  If its just a coil, then I would have expected a reading.  If it's some kind of other sensor, maybe it only changes state at point of ignition.  Anyone had any experience of these rather scarce machines?  Needless to say, new parts are unobtainable!

This is what they should look like - mine's a red one!

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Ian

[Bryanj]

Have you got a pick of the coil you are talking about?
If its by the crank and small its probably a trigger for the ignition and should have a resistance plus give out a millivoly pulse as the engine turns over

[taysidedragon]

If it's a small crank position sensor that's failed they are usually cheap to buy and easy to replace. There should be a  set gap between the sensor and the crank.

[Orcade-Ian]

Hi Bryan,
Thanks for the reply.  I haven't taken the side cover off yet, so don't know exactly what it looks like but there's one on fleabay for a GB250 Clubman, which is the same engine but in a cafe race style set up. Although it looks tatty, it might be worth a gamble if the seller could give a resistance reading before I jump in!

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I suspected it would just be an encapsulated coil triggered by a magnet on the crank to fire the CDI and hence the coil.  The primitive CDI is a small encapsulated box with a round connector with 6 pins - no diagram available to check.  Ignition coil and lead is easy, that's why I started with the pickup - which must be goosed.  I can't imagine it producing a pulse if it's reading O/C.

Ian

Sorry Gareth, I was tryping when you replied - no one seems to list one for this bike anywhere, xcept the used one I pictured.

[Bryanj]

Couldnt find that part on cmsnl but it looks like a trigger which senses a tothed wheel on the crank, my mates 1500 wing had one of two go down, changed them and all ok.
In the proper manual ,if you can get one, will be a resistance reading for it, usually somewhere 450 to 850 ohms so open circuit is definatel bad

[Orcade-Ian]

Hi Bryan,
The part is pictured and listed on CMSNL but NLA.  I've contacted the ebay seller to ask if he could measure the resistance - don't need to own another duff one!  Can't find a manual at present for the air gap so might have to experiment if this one proves good.

Thanks again,
Ian

[Bryanj]

30300KE5000 or 30300KE5010 and it does list the GB 250 as the same.
You might have to try different countries mate

[Orcade-Ian]

Thanks Bryan,
I'm awaiting a reply on the ebay one for resistance - if that proves positive I'll go for it.  Wonder if XBR use the same system? No doubt different wiring lengths, so different part numbers but I can modify.  I haven't taken the side cover off yet but I bet the actual business end is common to a lot of 80's stuff and not even just on Hondas. I'm in no rush but don't want to spend too much time or money until I know it's a runner - it will never be anything other than a rough hack.

Ian