Forum

[ChrisD]

Hi guys. I seek advice on the conversion of my twin-plugged Indian 535cc (1996) Bullet from points to electronic. The BoyerBransden fits successfully in the LHS toolbox and the wires are all long enough to reach their destination. BUT I don’t want to get the wiring wrong. My bike has the usual negative earth, so do I use the original coil leads to connect the Boyer “bluebox” (i.e. positive from ignition switch and negative earthing through the kill switch)? I have posed these questions to them and await an answer but I know that some of you have already done this and could advise.

Please. lets not get into a discussion of the plusses and minuses of twin-plugs or electronic ignition – the decisions were made, for better or worse, richer and much poorer, a long time ago!
In any case, I shall buy a Himalayan as soon as the sale machines arrive here in South Africa. I test rode a Euro4 for an hour or so on tar and gravel and that wonderful feeling of a bike that finally does it all, plus itchyboots videos, have sold me on it.
Cheers
ChrisD

[Adrian]

Is this BB's own coil , or is it manufactured by someone else (hopefully with a web site with some tech pages in English)?

A.

[ChrisD]

Adrian. This is the twin coil+bluebox set bought from our hosts (PN 92004) which comes with both coils. Sorry, I didn’t notice any manufacturer name but they are low resistance coils (~3.5Ohm).
Their wiring diagram is clear but takes no account of the vagaries of OEM Indian wiring!

I am in communication with Boyer and will respond with their advice on how to best wire-in the kill switch – and it will not be as it was with the OEM setup.
Cheers
ChrisD

[Adrian]

I can't see why our hosts have configured the kit for two coils when one twin-spark coil would have done, BB have them.

From digging around on the BB website, I see that some of their Micropower TCI boxes have a separate brown wire to use with the kill switch which goes to earth. Yours doesn't, maybe BB should include one with all their TCIs.

If your '96 Bullet still has the Magura switch gear, what sort of kill switch does it use? Is it an on/off switch for interrupting the power supply to the coil(s) or does it earth through the handlebars? The later K/S Bullets' Minda kill switch is simply an on/off switch with a wire in and out. One of my bikes has one set up to earth the magneto, though that means using the switch backwards, ie the bike runs with the switch in the stop position!

A.

[ChrisD]

Adrian – my Bullet has a kill switch breaking the circuit to the contact breaker.
I previoulsy used a dual output coil from our hosts. BUT that coil is not suitable if both outputs go to the same cylinder because there isn’t enough power to drive two sparksthrough the compressed fuel-air mix (that’s what I’ve been told). BB agree that the dual output coil is great for twin cylinder bikes not for singles esepcially if you rev up to ~6000rpm (steel conrod etc). So one must use two coils if you twin plug the beast. Once it is running, I may be able to advise the difference between twin coils or dual output single coil.

The diagrams appear out of order. SO: the second diagram is that of the Indian regular 500 Bullet showing only the section with coil, engine stop (kill) switch (at far left) and contact breaker (at far right).
As shown there, the operating the kill switch, opens the connection between the OEM coil negative (grey wire) and the black (or black/red) earth through the contact breaker.
These two wires must be connected across the two coils of the Boyer Bransden setup, as shown in the first image, so that operating the kill switch breaks the power circuit to the coils.
Similarly the white power lead to the OEM coil in the first image is used for the power to the pair of 6v coils in the second image.
NB: the supplied plug caps are 5000 ohm. If you use resistor plugs, you must use zero resistance plug caps.
Hope this is all clear. Boyer Bransden has agreed to me posting this information.
Have fun, ChrisD

[ChrisD]

Ooops guys, the images seem to have gone walkabout. SO herewith:

. Depending on the order they arrive, please sort out which is which!!

[Adrian]

Your diagram appears to show the two coils in series which suggests that they're 6V. If that is correct, and your kill switch merely interrupts the supply, I would have it wired between the ignition switch and the FIRST coil's positive terminal, instead of between the coils, so if it shuts off power to one it shuts it off to both.

A.

[ChrisD]

Adrian. That’s what I thought. But BB tech Dept say definitely that with the circuit on my Bullet (1996 Indian model) the kill switch must break the coil circuit "leaving the electronics working on time" - no, not like Dr Who.
I thought I’d covered all aspects but clearly missed out on saying the coils are indeed 6v and are therefore in series as you deduced.
Cheers, ChrisD

[Adrian]

OK, if they insist, wire it up like they say and see if it works. It is possible to reinstate the decompressor valve on a head which has been twin-plugged. I think Tim NZ posted details a while ago.

A.

[ChrisD]

Adrian. Yes, my twin-plugged head does indeed use the replaceble decompressor method of Tim-NZ and Glenn. In my case it is is installed between the rocker boxes with a 2mm diameter hole drilled through to the combustion chamber. This allows for decompression purposes, otherwise my 70-year old knee couldn’t handle the high comp 535cc kick. The only drawback of that method is that you cannot stop the engine with the decompressor. ChrisD