ET: Engine (Twin) Old Coil Ignition Points Identification

[Monkeypants]

The bike is 12 volt everywhere except the ignition.
It uses a ballast resistor to drop the 12 volt down to 6.
Norton Commandos had this same setup, 12 volt lighting/charging, ballast resistor and 6 volt ignition.
In fact the ballast resistor is also a Commando item, as are the 6 volt coils.
It was an easy start system on the Commando too, but the Commando ATD was poor.
I'm not sure how Triumph and BSA points equipped bikes were set up.
The thinking with the Commando ignition was that 6 volts was easier on the points than 12v.
They certainly last and last. The lifespan is way beyond what was normal with 12 volt North American distributor/ points.

Nigel, that is correct, the voltage theft with less than 20 thou gap is a peculiarity of this system for the Vincent. This doesn't occur on a 360 crank parallel twin.
I thought perhaps my system was a home made one off but John said no, it once was a manufactured item for Vincents. Apparently it was quite popular as these units keep showing up.

 

[Monkeypants]

Thinking about Erik's comment that points ignition is a part for Museum Mummies.

I think that would apply to my entire bike and the rider isn't far behind

Glen

 

[Michael Vane-Hunt]

Still not so old that you can't blow by a Washington State Trooper.

 

[Monkeypants]

That might have been an age related mistake, something a Mummy rider would do without a clue!

 

[Peter Holmes]

So on a single cylinder machine (Comet) running a Lucas distributer, with the cam and points heel kept well lubricated to avoid wear reducing the points gap, and assuming the distributer bearings are in good condition and the timing set to the correct point, what advantage would there be in running a 15 thou points gap as opposed to 12 thou points gap.

 

[Pete Appleton]

You need to have a wide enough gap to prevent arcing once the condenser charges up.

12 thou might be fine but with a small amount of wear it will become 10 thou. If it is running ok then no problem but if I was setting one up from scratch then I would go for the 15 thou.

 

[Peter Holmes]

Thanks Peter, that is just the sort of uncomplicated advice that I was looking for, my dilemma now is, leave as is, open up 3 thou and see how it runs or open up 3 thou and retime the ignition, might have to consult the Tarrot cards.

 

[oexing]

A better way is to fix any sloppy fits in an ignition system. You are lucky with a Vincent engine, not much of a chance to use a strobe there. You´d have to be prepared for some shocks to see timings all over the place with sloppy components unlike with large BMW flywheels and their markings of TDC, retard and advanced marks there visible in inspection/timing holes.

Vic

 

[timetraveller]

Vic, possibly you are not aware that there is a kit to use a stroboscope on a Vin. It was developed by Trevor Southwell over here in the UK and possibly in conjunction with some French friends. It fits into the big end quill hole and allows the engine to be run with oil going to the big end while the timing is done.

 

[oexing]

Thanks a lot, did not know - and will think about making one up later - much later in fact.

Vic