Misc: Ignition Twin Points Ignition

Oldhaven

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Pushrod Twin

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Brilliant Oldhaven, thank you, a whole thread with most of the answers, which I couldn't find!
So it appears from that, that I have a Norton, maybe Commando, advance mechanism which must have been fitted to a long shaft, and which I have now modified to add extra advance.
 

Pushrod Twin

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So I cut a degree wheel from the Triumph manual, altered the numbering, and attached it to the back of the chuck with Bluetac, then connected my strobe light. No visible advance in the lower speeds up to 1200RPM, but then at 1800 it not only advanced, but also centrifuged lumps of Bluetac around the shop and woke my darling wife! Ooops!
So much for the comment in Oldhaven's thread regarding getting all the advance in early. It appeared to confirm the 13-14 degrees it indicated static.
I will call it quits for now. The next installment will be when I fit it to the bike.
Right now, it's a sunny Sunday morning & the Classic Motorcycle guys have a ride organised, I'm taking my Vincent out for coffee, it deserves it!
 

Black Flash

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The single outlet coils on my racer are 0.3 of an Ohm......... Ignitech crank triggered ignition.
Hello Greg,
An 0.3 ohm coil should be a CDI coil. I doubt it will survive on a typical battery /points ignition. All coils I had so far with Norton, triumph, matchless etc running on points or early Boyer ignition systems were between 3 and 5 Ohm IIRC.
But of course if one has a coil lying around useless, give it a try for sure.
 

oexing

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A safe way to know what coil you can use in your system is to check the amps that go through the contact breaker. Obviously there must be a difference in ohms for 6 V or 12 V coils. But my bet is you can run a coil on your bike when current is well below 4 A , else the points will wear in no time. Capacitors are typically around 0.22 - 0.30 mF on all non-electronic ignitions.
As to excessive breaker wear today: What I miss on contact breaker systems is the grease/oil felt pad for cam lubrication. With car distributors old breakers were replaced at each maintenance and new Bosch grease applied to the cam. That was allright even for sixes and v-eights with only one breaker. So I don´t see a need for two sets for a twin, more hassles from that, just have two cams for one breaker at your specified firing angles, going with twin spark coils.
Once you got a grease felt there all should last for years on vintage bikes. But you defintely look for clean felt or dirt in it will produce a grinding paste on the cam. Lastly the cam has to be smooth and polished for minimum wear on the breaker heel. Fine wet´n´dry helps to keep the cam in shape and in case laser welding an very worn cam can restore it for decades of reliable operation. To be open, the most reliable ignition system seems to be the classic contact breaker coil setup, would not want to mess around with sophisticated electronics when a simple ATD is all you want. Magneto is quite good with rotating magnet, not the stone age rotating coil type with its trouble spots. Best design is one with ATD only on the breaker cam end like in Marellis, not in the Lucas drive end place. . The lasered cam below is from a Guzzi Falcone mag . The last photo shows ATD flyweights from a Vertex mag, no springs in the ATD, just a clever set of weights for a number of advance curves by selecting them.
Instead of messing around with old Lucas mags and D distributors no longer available I´d get a Saab distributor at € 50.- from Ebay, sense of rotation is the point for the ATD in it, and modify the cam for 50 degree v-twin. An adaptor for the engine case is no rocket science, a hub for the drive gear too. So then you get a good ATD, fat sparks, one breaker and easy timing.

Vic

Magneto Marelli cam:
P1040006.JPG


Vertex mag ATD weights:

P1070973.JPG


Vertex felt pad:
P1080010.JPG


Saab distributor:
P1090049.JPG


P1090058.JPG
 

Bill Thomas

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I don't think the D Distributor has a grease pad ?,
It's still my choice of Ign',
You can pick them up second hand, And there is a bloke in Devon U.K.
Has most spares, But not cams !.
I have ground one cam off a twin cam for a triumph and He supplied me with the weights,
To change to clockwise for a Comet.
Note, !!!!! He calls the Vincent anti clock, Looks at it from the other end, Not the drive end,
As we have been taught.

This is a Vin' Twin one I have.
 

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Pushrod Twin

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Here is another of Graham's favorite dead threads which might suddenly come to life again. :confused:
I have started fitting the twin points device to my Diecast C engine. First up it interfered with the case & needed relieving to ensure that the body sat flat and square on the adapter plate. I filed a little off the front of the case and a bit more off the points device body at two places, front of case & oil filter protrusion, until I had about .010" (0.25mm for Vincent :))
 

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Pushrod Twin

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Finally, and at last, I have the twin points system running! First start was several weeks ago, just to prove that it would run, while I continued other work on the bike. It was a miserable rainy night so I poked the back end out the workshop door towards the neighbors fence, it started easily enough, ran it long enough for the return oil to appear, blipped the throttle a couple of times to confirm both cylinders were alive, then shut it down before the neighbors called noise control. :D
Then I fired it up about a week ago. Again, it started easily, but coughed & spluttered a bit as I staggered off down the road. However, after warming up and getting out on the open road, it cleared it's throat & ran well. In fact, there was a noticeable improvement over the tired magneto. It would drop back to 30 MPH in 3rd gear smoothly, without "hunting" and lurching as it had previously. Twelve miles was not a big test.

Today I got 128 miles of good riding in. Starts easily, in fact the points are clearly making sparks at kick starter push through speed, as it fired a shot on one lung with a part charge of fuel. Still a bit of coughing as it warms up, I'm putting that down to oil in the chambers having run down the guides while sitting for a week, which will make any spark system work hard.
Then on the open road it clears up and pulls well. There was no hesitation, or flat spots. It is happier at low revs that it was with the mag & factory ATD, it will drop to chain snatch speed, 40 KPH, in 3rd gear. It accelerates for passing similarly to previously, but without misfiring as it did with the mag. I was concerned about the advance range so I rode south to a hill known locally as the Lion's Back. This bike has always accelerated happily up there, but excessive ignition advance is easily exposed with the traditional pinking (Pinging for the Murcans) when accelerating hard.
It accelerated cleanly, & hard, passing a 1200 Sportster, at somewhere in excess of 140 KPH and climbing, according to my GPS.

Inspection when home indicated the points had closed a little to .017" so I adjusted them back to .020". I will put that down to heels bedding in and will monitor it. The points contact surfaces were clean & smooth. There was evidence of fresh oil at the bottom of the body, I will put that down to me over oiling the oil lite bushes, and monitor that also.

Conclusion; I'm hooked, overall the twin points system is performing better than the tired mag. I will continue to ride it, monitor the performance, and have the KVFTT repaired for future options.
The exercise has confirmed to me the opinions of a number of people, the factory ATD is less than perfect, particularly if it has done any serious work as most have, and there are more satisfactory options available to provide an improved ride. :)
Finished item,1,20210801_194947.jpg
 
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