Lights

Mickthevin

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Non-VOC Member
CAN ANYBODY GIVE ME SOME ADVICE ?
I HAVE TWO COMETS BOTH OF WHICH HAVE DECIDED TO GIVE UP THE GHOST WITH REGARD CHARGING THE LIGHTS. ONE HAS ELECTRONIC IGNITION WHILST THE OTHER IS ORIGINAL. WHAT I NEED TO KNOW IS WETHER IT IS WORTH GETTING BOTH DYNAMOS REFURBED OR SHOULD I GO FOR SOMETHING DIFFERENT. EVERYTHING ELSE ON BOTH BIKES IS FINE [ AT THE MINUTE ]AND THIS IS DRIVING ME NUTS
COST IS NOT A MAJOR ISSUE - I JUST WANT THEM BOTH TO WORK AS THEY SHOULD
THANKS IN ADVANCE
MICK:confused:
 

john998

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VOC Member
Dear Mick,
It depends on how you use your bikes. If like me you follow Joe Lucas's dictum that gentlemen do not go out in the dark, then referb is the answer. The bike with electronic ignition would probably benefit from conversion to 12 volts.
My solo is 6 volts still, with a Ken Bell electronic regulator, an excellent unit. The mag also has been trouble free, providing sparks for all these years, without any work other than an odd clean and grease.
The dynamo is the one fitted when I bought the bike 42 years ago. All it has had is a clean out at about 10 yearly intervals.
The outfit has a Chinamo, with a Gardener 12 volt electronic unit, this has proved to be an excellent combination (pun intended). Standard coil ignition system gives easy starting even with the small wheels restricting the swing.
Not sure if the Chinamo is still available, but it is no use to you on a Comet without a machining job.
Not able to comment a on Alton as very little experience on it.
Regards John.
 

rapcom

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I can only reiterate the advice that you need to evaluate your planned usage of the bikes, and how important "originality" is to you.
Do you ride only on sunny Sundays in the summer ?
Do you ride all year round in all weathers ?
Do you want indicators, higher power headlight, heated grips, electric jacket ?
Do you want your bike to look "standard" ?
Work out your required wattage/amperage, at what speed, and then evaluate.
There are now several options.
1. Refurb original Miller or Lucas dynamos, and use a modern solid state regulator (and converter to 12V if you want).
2. Fit a Chinamo (but I don't think they available new any more).
3. Fit a McDougalator (based on a Kubota alternator, I believe, but I don't know if they fit Comets).
4. Fit an Alton (now on the third version, back to single phase).
5. Fit one of the car alternator conversions for more output than any of the others, but does not look standard at all.
There is plenty of choice to suit all requirements, a well-refurbed old dynamo will suffice if you are the fair-weather summer rider, a car alternator will be better if you use the bike all year round.
Your choice....
 

nkt267

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VOC Member
Hi Mick. what dynamo have you got? If it is a lucas disconnect the wires from D & F. Join D & F with a short bit of wire,connect 1 side of a 12volt bulb to earth and the other to the link and start the bike.Keep revs fairly low,as you can generate 20 volts like this,if the bulb lights then the dynamo is most likely OK and the problem is further up the sytem.
If you have a Miller then I am not sure how to check the output without the regulator.The last Miller I had was converted to Lucas type by only using the field winding and ditching the control winding and it works perfectly. This is in 1 of the 'bibles' but can't remember which one.. Ive got a Alton somewhere in Europe,had to return it as the bearing went and would only balance the lights at 50mph on a Comet.If you saw my Comet in the Island then it has now got a peugeot alternator running off a dummy shaft and it runs everything(lights,coil ingnition)+2amp charge at 30mph.John
 

Mickthevin

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Non-VOC Member
Thanks For Your Comments. I Should Have Made Things Clearer - Both Bikes Are 12v , Both Bikes Still Have The Original Dynamos But I Dont Think They Have The Original Regulator. I Have Made Two New Wiring Looms Following Richardson With Led Lights On The Back And Quartz Halogen On The Front. I Dont Have Or Want Indicators. One Comet Is Bored And Stroked And This Has Electronic Ignition - The Other Has The Original Magneto.
I Am Not Bothered About Originality Because I Cant See The Point In Having Bikes That Dont Work.
I Suppose I Am Now A Fair Weather Rider Due To Lack Of Time With My Business But If A Nice Day Is Apparent Then I Make Every Effort To Go For A Ride No Matter What Time Of Year It Is - No Lights In The Winter Severely Resticts Where And When You Go.
I Look Forward To Any Comments
Regards

Mick
 

nkt267

Well Known and Active Forum User
VOC Member
You still come back to the problem of whether the regulator or dynamo is at fault.I would be severely teed off if I had paid to have dynamo's reconditioned only to find out it needed a £40 regulator. the set up I have got now(see prev reply) cost me less than £50.
 

rapcom

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VOC Member
Mick, Please reconsider about not wanting indicators. I don't know what the traffic is like around Whitley Bay, but here in the South East of England, making hand signals in the dark, in the rain, in heavy traffic, is as much use as a bicycle to a haddock. You WILL get wiped out sooner or later, especially on right turns. Be seen.
 

Monkeypants

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Non-VOC Member
I agree with Rapcom, turn indicators are essential. I'm adding some extra indictors to the top box as the rear ones I have on the plate holder are quite small.

The new Alton seems to be a nice unit, plenty of power at low revs, reasonable cost and it's appearance is almost identical the original dynamo. In addition, with an alternator you do away with the wear/failure problems associated with brushes and commutator in a dynamo.

The chimanos also work well, especially when converted to 12 volts with a JG, but do not put out as much power as the new Alton.

The new Alton will run points coil ignition (25watts) plus a 60 watt headlight (75 watts of light total inc tailight and speedo lights) plus run a heated vest and balance all of this at around 52 mph in top gear (standard gearing) The chinamo at 12 volts with JG unit will run the same load minus the heated vest (35 watts) and balance at about the same speed or slightly higher. It will not run lights and vest combined at any speed, it is one or the other. This is a problem for me on a cold night, so I tend to use the bike with the Alton if the vest and lights will both be needed.

Since neither of your bikes are point/coil ignition, you probably could run a powerful (60 watt halogen) headlight and a vest at the same time with just a chinamo on 12 v, provided you keep the speeds up.
I'm not sure how the Alternator speed/ road speed of a Comet compares to a twin and the number above are for a twin.

I would probably opt for the Alton as it is readily available new and has greater power which , although you may not need now, will be useful if you decide to tour Scotland in September or some other place with a typical Northern climate.

The other consideration is that new Chinamos are no longer available and repair parts for the Chinamo could be tough to find over time.
 

rapcom

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VOC Member
Mick, Remember that the Comet dynamo gearing is different to a twin, so the load balancing speeds or outputs that are quoted on twins will have to be factored to get an idea of how they apply to a Comet. On a twin the dynamo runs at 1.25 x engine speed, but on a Comet it is 1:1. The recently quoted speed of 52mph to balance a load, if on a twin, starts to look silly if factored to a Comet.
 

Monkeypants

Well Known and Active Forum User
Non-VOC Member
Mick, Remember that the Comet dynamo gearing is different to a twin, so the load balancing speeds or outputs that are quoted on twins will have to be factored to get an idea of how they apply to a Comet. On a twin the dynamo runs at 1.25 x engine speed, but on a Comet it is 1:1. The recently quoted speed of 52mph to balance a load, if on a twin, starts to look silly if factored to a Comet.

Given this information, the actual alternator speed for either the Comet or the twin at 52 MPH in top gear can be calculated.
The Riders Handbook states that with standard gearing a twin engine does almost exactly 4600 RPM in top gear. This means that at 52 MPH the engine will turn .52 X 4600= 2392 RPM and the Alternator will turn 2392 x 1.25 = 2990 RPM.
For the Comet, the Riders Hand book states that with standard gearing the engine turns 610 RPM for every ten miles per hour of road speed , so at 52 MPH the Comet engine will turn 610x 5.2= 3172. Rapcom has stated that with the Comet the engine/alternator ratio is one to one so the alternator will also be turning 3172 RPM. Since the Alton balances my 130 watt load at 52 MPH on my twin, on a Comet at 52 MPH you should show a slight positive charge with a 130 watt load, with balance happening around 49 MPH.
So for any given road speed in top gear the Comet will turn the Alton faster than the twin.
The new Alton puts out lots of power at low speed with a twin and will do even better (slightly) on the Comet.
 
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