• Welcome to the website of the Vincent H.R.D. Owners Club.

    Should you have any questions relating to the Vincent H.R.D. Owners Club, or Vincent H.R.D. motorcycles in general, please contact Graham Smith, Hon. Editor and Webmaster by calling 07977 001 025 or please CLICK HERE.

    You are unrecognised, and therefore, only have VERY restricted access to the many features of this website.

    If you have previously registered to use this forum, you should log in now. CLICK HERE.

    If you have never registered to use this website before, please CLICK HERE.

ET: Engine (Twin) Old Coil Ignition Points Identification


Glenliman

Well Known and Active Website User
VOC Member
The rear 6 volt coil ends up getting fed with 3 volts when the gap is narrowed on both sets of points.
It's not enough to fire the plug.

Re the worn out parts comment-
The bike can be seen at 1:35 and 4.00 in Gerry's video of the 2007 IOM Vincent Lap.
This is about 20,000 miles after the 1 cylinder problem, but same ignition, same old Lucas points.
The bike had enough speed to pass 31 riders on the lap including five twins all lined up racing WFO, riders flat on the tank and doing over the ton on the Sulby Straight. A lovely Godet restored Black Shadow was leading the charge at about 115 mph by my speedo. Even managed to catch and pass him.
Would that be possible with a "clapped out" ignition?


Glen
 
Last edited:

Bill Thomas

Well Known and Active Website User
VOC Member
It is noticeable that the cam profile on the multi cylinder aero mag is very short and lumpy, thus giving maximum dwell time regardless of point gap.

A typical coil will require 2.5 milliseconds to achieve a reasonable saturation in order to give a decent spark. At 4,000 RPM that equates to 60 degrees of crankshaft movement. With an unknown cam / points setup it is worth checking that this figure is attained, something that I suspect Stu, above, already knows.
A small point gap will increase dwell and, as Simon mentions, will waste electrical power and could overheat the coil. Charging past the saturation point has no advantage.
Talking of charging the condenser in the same context as dwell is not really correct. Dwell is when the points are closed. As one side of the condenser is connected to earth and the other is connected to the points the condenser is discharged during the dwell time. Its main function is to quench the voltage rise as the points open in order to prevent arcing and provide a clean break. The points must be open wide enough by the time that the condenser is charged so that they are then unable to arc. Too small a gap can lead to arcing and will give similar symptoms to a failed condenser.

I agree with Vic that if a reduced points gap, when measured static, is cutting one cylinder out then it is likely to be wear in a component causing the gap to be further reduced when under running conditions.

But hey, if decent points and a 25 thou gap fixes it then who cares?View attachment 28230
Hello Pete, Just fitted a "D" Distributor to Ron's Comet, With a very Pointy single cam, Don't know where it came from, 12 v, Starts well and goes well, Should I be worried about Coil failure. Cheers Bill.
 

vin998

Well Known and Active Website User
VOC Member
VOC Forum Moderator
If I recall on Glen's bike when it had the small gap and running two sets of points on a 50 deg engine (as it was designed for a parallel twin) something about one set of points grounding thru the other when the one of the sets was supposed to be trying to deal with the coil, and that was why it went onto one cyl and why opening the gap to 25 thou let it function as god (and Lucas) intended. Certainly it was nothing to do with worn components!
That now explains what is occurring on Glen's bike. As it was originally a parallel twin unit I suspect one set of points has being moved to alter to 50 deg configuration. This could bring in the problem that Peter has described where the both points can be closed at the same time or more likely very close to that situation so the coil doesn't have enough time to fully saturate and so no spark on one cylinder. What is really required is a new cam profile, but by altering the gap to 25 thou gap it has altered the dwell angle enough to allow both cylinders to fire and overcome the problem.

Simon
 

erik

Well Known and Active Website User
VOC Member
On my early Commando I had nearly the same construction with atd unit behind the Points .It never worked properly and the atd unit never worked as it should.I converted to boyer electronic ignition and the Troubles were gone.enginine running smoother ,lower consumption of gasoline and no more Timing Troubles.It is in the bike for more than 25 years!!To my mind it is a part for a mummie in a Museum.Regards Erik
 

Glenliman

Well Known and Active Website User
VOC Member
The ATD on this arrangement is different than the Commando.
I agree electronic ignitions can be excellent. Most important for any ignition is that doesn't leave you stranded roadside.
In 57,000 miles this ignition has only given me trouble once, self induced after fitting the expensive but low quality points, for the reason discussed. Even then I was not stranded, I just had to figure it out.
So I don't see this setup as something that is made wrong , should have a different cam profile, needs an " alterred gap" to overcome it's problems or has clapped out parts.
Most everything has a spec and the spec for the system is 25 thou gap. Then it works very well, you couldn't really ask for more from it.
The Electronic ignitions all seem to have their issues, Boyer quite often had the broken pick up wire problem. Boyer has lots of haters although I have had good luck with Boyer on Nortons.
Other Electronic ignitions will fry the black box now and then. Trispark is particularly well known for this.
Pazon might be the best of the bunch, but even those have the occasional failure.
With the points bike I now carry a complete spare ignition ( just 1 coil tho) and it's all pretty simple to work on roadside if it ever gives trouble.
My main goal was to help Rob ( the original poster) and maybe save him some grief, given that I have used that same ignition for so long now with only that one early issue.




Glen
 
Last edited:

erik

Well Known and Active Website User
VOC Member
@ Glen : I agree with you that on the Norton twins there is boyer a satisfying solution.On my Comet I have the original magneto fitted with a nos atd unit.No Problems.When I started to restore my rapide there was only the half of a Pazon ignition with the bike and so I diceded to go the BTH way.I hope the bike is next week with TÜV and on the road, then I will see if this decision was a good idea. Erik
 

Nigel Spaxman

Well Known and Active Website User
VOC Member
I am trying to understand why Glens ignition doesn't work with .015 gap. The same ignition works with .015 gap on Triumphs, Nortons, and also the BSA and Triumph Triples. It guess the triple is like a vee twin with a 120 degree angle between the cylinders and a third cylinder added. You would almost think that you could add as many of these circuits as you wanted and it would still work.
I guess it must have to do with the dwell. When either set of points open that should cause a spark if the coil is charged. It may be though that the dwell is such with the .15" gap that just before the points open on the rear cylinder, or more or less simultaneously, the points close for the front one. When the front points close the condenser for the front cylinder is suddenly connected to the circuit, maybe that right at the worst possible time causes a drop in voltage to the other coil and condenser, and it discharges the other coil just before it needs to fire?
 

Glenliman

Well Known and Active Website User
VOC Member
Nigel, its the voltage drop that occurs when both sets of points are closed while the rear 6 voltcoil is getting charged. With narrow gaps the voltage available is 3 volts.
With the proper gap the voltage is 6 v, as it needs to be.
John McDougall told me this early on, it took a few minutes of looking at it quietly to figure out why.
The prospect of riding a 1 cylinder Rapide for 400 miles through the mountains tends to focus the mind!

Glen
 

peter holmes

Well Known and Active Website User
VOC Member
For those of you that know how to use a slide rule, or even one of those new fangled electronic calculator things, I think Sinclair might make them, if I change my current points gap on my single Lucas distributer fitted to my D Comet from 12 thou to 15 thou, how much will it advance or retard my ignition timing, I have only had it set on 12 thou for the past 10 years because that was the figure in KTB.
 

Nigel Spaxman

Well Known and Active Website User
VOC Member
Peter I doubt you can figure out how much difference to the timing .003" of gap would make without knowing the shape of the cam that lifts the points. My guess would be that it the timing difference would be less than 5 degrees.

Glen, I had forgotten about the 6 volts and the voltage drop. On most of the other bikes with this system it is 12 volts so maybe there is less voltage drop. I think on the vertical twins the firing points being 360 degrees apart instead of 310 and 410 on the Vincent might help, maybe on those bikes there is never a time when both points are closed at once.
 

Glenliman

Well Known and Active Website User
VOC Member
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.
 
Last edited:

Glenliman

Well Known and Active Website User
VOC Member
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
 

MSVH Y3

Well Known and Active Website User
VOC Member
Still not so old that you can't blow by a Washington State Trooper.
 

Glenliman

Well Known and Active Website User
VOC Member
That might have been an age related mistake, something a Mummy rider would do without a clue!
 
Last edited:

peter holmes

Well Known and Active Website User
VOC Member
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

Well Known and Active Website User
VOC Member
VOC Forum Administrator
VOC Forum Moderator
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

Well Known and Active Website User
VOC Member
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

Well Known and Active Website User
VOC Member
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

Well Known and Active Website User
VOC Member
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

Well Known and Active Website User
VOC Member
Thanks a lot, did not know - and will think about making one up later - much later in fact.

Vic
 

Latest Forum Posts

Latest Forum Threads

Top