Engine misfire, electronic ignition.

[Dickthebass]

Was recently riding my B40, when it started playing up, it started spluttering as if it was about to run out of petrol, and started backfiring like you've never heard before so loud, the plug was a bit sooty, replaced it and carried on with my journey.
Next time out I got about 10 miles away when the same thing happened, the bike cut out, and again massive backfires, bike will restart near enough straight away.
I got the bike home and replaced the plug cap lead and coil, took for a test ride, got about 5 miles down the road and bike cuts out again.
Stripped the carb and cleaned it, no obvious problems found.
Bike is still not running right.
The exhaust has started to turn blue,
I have Wassell electronic ignition fitted to my b40, all of the connections seem to be secure, I've not used a voltmeter because I have never used one, however according to my ammeter the bike is charging, lights certainly brighten when the engine is revved.
Has anyone had similar problems with electronic ignition on 12v singles.?
Any idea as to where I look next, .??

[neil1964]

Assuming timing is correct ( sounds about right given starting) your description sounds like dirty fuel/intermittent weak mixture so could also be an air leak in induction system that is worse when hot. ie popping, banging, spitting back and blue exhaust pipe.
I'd check manifold for air leaks, carb gaskets, clean fuel/tank and filters. Make sure tappets not too tight.
What carb are you using?  How old is it ?  Few simple things to check.

[DAVE BRADY]

Hi,

This could be timing related.  Does the Wassel EI still function with low battery voltage? It could be that it is not advancing properly hence the popping and bluing exhaust.
I would check that the charging system is maintaining a fully charged battery and that the battery is holding its charge. Otherwise, a faulty wire in the ignition system particularly between control box and pickup.
This happened to me on an A65 and ran as you describe. There was poor continuity in the pick up wires and once replaced all was fine.

Dave.

[franknjan]

I had similar issues on my b441 fitted with Wassell vape electronic system.
I went through everything and changed everything including the ht coil. Evey test run got shorter and shorter. In the end I fitted a boyer bransden kit00280, specifically for bsa singles, consisting of ignition unit, ht coil, plug cap and ht lead. The engine starts easily and so far, has proved reliable.

[V500]

I've heard bad reports on the Wassell unit too. No surprise really, given Wassell's reputation.

[Roy]

Just like to say I have had/ used / fitted many of the wassell supplied Vape units and to be honest have found them very reliable, the latter one have a much greater voltage range and less likely to give probs should the battery voltage drop , that's my opinion anyway ,as ever all the other electric components and wiring on machine should be in tip top order , over the years I have had coils play up particularly if they hard not in air flow or get to hot ,
Hope you get to the bottom of you problem ,regards Roy

[Beesy]

Did you try a different ignition coil?

[Dickthebass]

Did you try a different ignition coil?

Yes mate a couple of them..

[Dickthebass]

Hi,

This could be timing related.  Does the Wassel EI still function with low battery voltage? It could be that it is not advancing properly hence the popping and bluing exhaust.
I would check that the charging system is maintaining a fully charged battery and that the battery is holding its charge. Otherwise, a faulty wire in the ignition system particularly between control box and pickup.
This happened to me on an A65 and ran as you describe. There was poor continuity in the pick up wires and once replaced all was fine.

Dave.

I am going to strip it down hopefully this weekend, and try and find anything obvious,
But if not I'll replace it with a new unit and see where we go to from there,
As you say the test runs are getting shorter and shorter..

[Dickthebass]

Assuming timing is correct ( sounds about right given starting) your description sounds like dirty fuel/intermittent weak mixture so could also be an air leak in induction system that is worse when hot. ie popping, banging, spitting back and blue exhaust pipe.
I'd check manifold for air leaks, carb gaskets, clean fuel/tank and filters. Make sure tappets not too tight.
What carb are you using?  How old is it ?  Few simple things to check.

The carb is a standard Amal 376/253 fitted new about 6 years ago I had the carb off last week cleaned all out, There was some wear on the slide, but everything seemed to be ok, new gaskets fitted etc.?