Twin-plugging.

[Le singe]

After reading a few comments here, it seems the BMW spark plug mounted coils are too reliable.
I've just purchased a pair of 1100S twin-plugged cylinder heads for yet another modification. I'm planning on machining the heads for an additional plug hole diametrically opposite the 'second' plug hole, then using just the 2 outer plugs.
As I've got carbs and a different ignition system, I will be using 2 times ignition coils each with a pair of leads.
It would be interesting to see if the standard twin-spark set-up could revert to using 2, twin-lead ignition coils because they don't seem to give a problem.
Replacing 4 plug-mounted coils at £55 a time is a bit daunting!

 

[Bigtwin]

After reading a few comments here, it seems the BMW spark plug mounted coils are too reliable.
QUOTE]


Not entirely sure you mean this?

 

[cookie]

must be a not missing

 

[Steptoe]

.
Replacing 4 plug-mounted coils at £55 a time is a bit daunting!

It's only the primary spark plugs that have the inbuilt coil HT leads, the secondry spark leads are normal

 

[Le singe]

Oops, yes, the 'not' escaped!
Thanks for the info on the coil situation, Steptoe, I wonder whether BMW went for plug-mounted simply because it was impossible to get 2 conventional coils under the tank?
Unfortunately I don't know anyone here who has a twin-spark model, and I don't think the dealers would be too happy about one being dismantled. I suppose I could always ask for a test ride and take a bag of tools!

 

[(RIP) Kaister]

all 4 cyl jap bikes have 'twin spark' coils.

wouldn't they work ?

its only a transformer .

 

[Le singe]

That is the plan, to use 2-off, twin-lead coils, as per the standard GS ones.

 

[Rob Farmer]

I fitted a couple of small twin output coils to my last airhead. fitted together they were no bigger than the standard airhead coil. They were designed for a microlight apparently and were £60 a pair. Motobins do them as well for a little bit more (part 70506 @£29 + VAT)

 

[Le singe]

Thanks for that, Rob. They are the same ones I used when I twin-plugged my brother's airhead.