BSA Owners' Club Workshop Discussions

The BSA Workshop => Twins => Topic started by: OLDBEEZAGEEZER on 09 Aug, 2025, 09:59

Title: 59 A10 wassell EI
Post by: OLDBEEZAGEEZER on 09 Aug, 2025, 09:59
I have no sparks. I installed a new if sw and have power to the micro mk1 ignition unit from the switch but nothing going to coils.
I have checked all connections and earths and battery is fully charged.
How does the micro mk1 work?
How can I test it?
Any ideas would be appreciated.
It was working prior to old switch packing up
Title: Re: 59 A10 wassell EI
Post by: DAVE BRADY on 09 Aug, 2025, 10:08
Hi,

Is the switch exactly the same type?
Did you disconnect the EI to coil wires?

Dave
Title: Re: 59 A10 wassell EI
Post by: iansoady on 09 Aug, 2025, 10:18
Normally there's nothing going to the coils from Boyer black boxes until they're energised by seeing the magnets pass the pickup coils. I haven't heard of a Mk 1 system - the only ones I know are Mk 3 and Mk 4.

Boyer has some good instruction sheets: http://www.boyerbransden.com/instructions.html
Title: Re: 59 A10 wassell EI
Post by: OLDBEEZAGEEZER on 09 Aug, 2025, 10:49
Dave,
Exactly the same switch.
Did you mean did I disconnect coil at all or when I tested for power?

I have feed to switch to ignition unit but nothing coming out. I have plugs earthed to cylinders but nothing spark when I kick it over. Several times to 'wake up' the unit.
Title: Re: 59 A10 wassell EI
Post by: DAVE BRADY on 09 Aug, 2025, 10:54
Hi,

I always try to retrace my steps with things like this.
If it was working before then the problem has arisen from what has been done.
Usually an EI will make a spark when the ignition switch it turned on and off.

Dave.
Title: Re: 59 A10 wassell EI
Post by: iansoady on 09 Aug, 2025, 15:17
As Dave says, will spark when the ignition is switched off (some configurations also when switched on). You can also disconnect the hellow/black and white/black wires going to the pickup coils and there should bae a spark if the 2 leads from the blasck box are touched together.
Title: Re: 59 A10 wassell EI
Post by: OLDBEEZAGEEZER on 29 Aug, 2025, 17:45
Thank you all for replies. Have been checking through suggestions in between domestic duties and and after checking switch operation, wiring for breaks/continuity, power to coil all ok.

Checked primary coil resistance. ok.

Checked ht to primary connections. nothing.

This emgo dual coil lasted about two hundred miles and is my third one!
 I've had a 50 year old Honda for 30+ years and it still has the same coil.

What causes them pack up?
Is there an ideal position for it on 59 flash? It currently in the tool box and the first one was under the battery behind the ski ramp.
Title: Re: 59 A10 wassell EI
Post by: JulianS on 29 Aug, 2025, 19:12
I mounted the twin output coil on a heat sink on the rear mudguard. Apart from the obvious the heatsink also makes mounting it easier. The coil and heatsink are Boyer parts in the photos.
Title: Re: 59 A10 wassell EI
Post by: OLDBEEZAGEEZER on 30 Aug, 2025, 10:30
Julian, I like your idea.have you fixed the heat sink to the mudguard?

That area is a bit more cluttered on mine with indicator relay, fuses and larger battery but nothing that couldn't be re homed like in the toolbox when coil comes out.
Title: Re: 59 A10 wassell EI
Post by: JulianS on 30 Aug, 2025, 13:30
Yes it is bolted to the rear mudguard.

The heatsink from Boyer cost about £15 posted to me and delivered next day from Boyer. They come with  holes drilled and aluminium pillars to mount the coil. The coil mounting centres are 90mm (some coils are 100mm I think) I drilled the holes for mounting on the mudguard.

When I bought the Boyer twin coil the instructions made comment about heat. You can read the instructions on the Boyer site

http://boyerbransden.com/pdf/COIL00004.pdf
Title: Re: 59 A10 wassell EI
Post by: OLDBEEZAGEEZER on 02 Sep, 2025, 14:26
Thank you for the info Julian. It is very helpful.
I have asked Boyer about the coil and they can't say whether the 00004 coil is compatible with with my Wassell system. I also contacted burton bike bits and they think that coil is for bikes with alternators.
Looks like I'll have to get another EMGO and re position it with a heat sink.
Alan
Title: Re: 59 A10 wassell EI
Post by: DAVE BRADY on 02 Sep, 2025, 17:17
Hi,

Does dynamo or alternator make a difference as the battery is supplying the power.
There have been several posts with issues re Wassell EI.

Dave.
Title: Re: 59 A10 wassell EI
Post by: JulianS on 02 Sep, 2025, 17:46
The Boyer coil works fine with the Boyer mark 4 black box and dynamo on my A10.
Title: Re: 59 A10 wassell EI
Post by: DAVE BRADY on 02 Sep, 2025, 18:12
Hi,

Re Emgo twin lead coil.  We have used these on our bikes for many thousands of miles with no need for replacement.  I think they came with a heatsink and the bolts for fixing.

Dave.
Title: Re: 59 A10 wassell EI
Post by: OLDBEEZAGEEZER on 02 Sep, 2025, 18:21
I wouldn't have thought it would have been any difference re dynamo or alternator as long as the resistance figures were comparable but that's why I asked the question.

My EMGO had bolts but not a heat sink so I will fabricate one to fit the new coil location.
Alan