Ignition Woes

[Duccout]

Any electronics wizards here?

Last year my 350 broke down; one day as I approached a road junction the engine died, but it restarted straight away. A week later it did it again and was dead with no spark. Nigel and Edina were brilliant with helping me to find the fault with the Electrex World ignition (which turned out to be the pulsar ring). Today it has begun to play up again, stopping twice on a closed throttle as I slowed for a road junction, and both times restarting readily, just like before. Of course it could be something else causing the problem, but the odds are that the ignition is failing again.

Does anyone have any idea why it should die on a closed throttle rather than under load? And assuming that it is the ignition, what could be the cause? I went through the whole system last time and fitted a new ignition switch, so there is nothing obviously causing it and I don't want to shell-out for another ignition system. I can't risk using the bike again because getting stranded is not great!

Cheers,

Colin.

[mrkprsn]

I just had a situation where I could start my Sebring and it would immediately die. The spark plug wire had pulled away from the ignition coil enough to show a week spark but not enough to keep the bike running.

If it were me I would start at the spark plug and move towards the ignition. Just for fun switch to another spark plug. Then make sure you are getting 6/12v at the ignition coil. Then test the coil for resistance (6k between secondary and primary and 1.8 between primary windings). If that all pans out then it might be the electronic ignition. I run points on my bikes and I just finished a motogiro, so I know they can work if set up correctly. Do you have the original ignition and can you try that? Assuming this is a DC system.

[Duccout]

Thanks. I do not have the original points system, that is long gone.

[IanHood]

Colin,

I think I may be having a similar issue. I have the Electrex system from Nigel and the symptoms sound the same. I actually ended up with the bike having to be put in the back of a van last Friday (after a 6 hour wait) because it wouldn’t start after a half hour run. Funny thing is, it started easily the next morning!

I’m now nervous about taking it out again without knowing what the issue is

Ian

[Duccout]

Hi Ian,

Hmmmm. Many people are using these ignition systems with no trouble, so possibly there is a quality control issue, or maybe a problem with the wiring on individual bikes. I had the pulsar ring fail and Edina said rhat she had never had one fail before. I may ring Electrex World and ask if there is something specific that could cause this, although I have no idea what is in the pulsar ring to fail. Mine was intermittent; one minute there was no spark, the next there was. As you say, once the system plays up you can't trust it again.


Colin

[IanHood]

Let me know what you find out Colin. I went to the extent of pulling a side cover off to make sure the stator wasn’t slipping on the crank (it wasn’t) but I don’t really have the expertise to test electronic ignitions, particularly intermittent issues.

Ian

[Duccout]

I have the same ignition system fitted to my 250 which has never given any problems, which leads me to think that there must be a fault in the 350 wiring somewhere; either that or I am just unlucky with the 350.....

Colin

[IanHood]

I’ve just spent some time checking resistance on all the connections on my bike and have found slightly high resistance in one connection in the connector block between the pulsar ring and the CDI. That could be my issue. I’m going to solder the wires and heat shrink rather than using a connector block and then will cross my fingers…

Ian

[Boxprod]

Dear Colin,
I'm sure that the Electrex system is considerably more sophisticated than my original 1970s Motoplat CDI - and I know lots of people are rude about that, but I've found it to be pretty hardy - but for what it's worth, any and every problem with the old Spanish ignition has been down to slightly dubious earthing.
It seems that electronics can detect even small fluctuations in current, and respond by defaulting to limp mode if you're lucky, or dead mode if not.
Just a suggestion, which I hope ain't too annoying in the midst of your challenges.
Best of luck,
Pete.

[Duccout]

Hi Pete,

When I feel a little more enthusiastic I will go over the wiring again (thank God these old bikes are so simple) and see if I can find something that could be the cause. I recall the time when my 750 Ducati started cutting out when I pulled away and I couldn't find the cause until one day I noticed that it happened as I released the clutch and found that the cable was moving and shorting out one of the coils.

Cheers,

Colin