Is it feasible to fit a smaller sprocket and speed up the dynamo?
Urgent - Comet Lucas Dynamo doesn't appear to be charging
- Thread starter ah_sprite
- Start date
Hi
The old Miller regulator is not very good and there are problems with setting it up. I could never understand why they used their system and guess it was because Lucas had a patent on the more obvious and better system.
However some authorities say that the Miller dynamo is in fact a better piece of kit than the Lucas one which was standard fit on many British bikes. If this is the case then a modified Miller dynamo with an electronic regulator should provide a good and reliable system.
Certainly the Miller on my Comet had been very reliable up to the time when the old electro mechanical regulator expired, and has been faultless since I modified the system to fit an electronic regulator many years ago.
I am still running at 6volts for originality and have to admit the lights are certainly not as good as those on my Honda VFR750!
In fact at any speed much more than 60mph I tend to run over the headlight beam with the Comet !!!
Matty
The old Miller regulator is not very good and there are problems with setting it up. I could never understand why they used their system and guess it was because Lucas had a patent on the more obvious and better system.
However some authorities say that the Miller dynamo is in fact a better piece of kit than the Lucas one which was standard fit on many British bikes. If this is the case then a modified Miller dynamo with an electronic regulator should provide a good and reliable system.
Certainly the Miller on my Comet had been very reliable up to the time when the old electro mechanical regulator expired, and has been faultless since I modified the system to fit an electronic regulator many years ago.
I am still running at 6volts for originality and have to admit the lights are certainly not as good as those on my Honda VFR750!
In fact at any speed much more than 60mph I tend to run over the headlight beam with the Comet !!!
Matty
- Have just seen the question about the smaller sprocket. This may well be possible in some way with a twin where I believe the dynamo is driven from the primary chain. However for a Comet the pitch of the teeth of the gears is the same for all the timing gears and their spacing is fixed by the crankcase design so it would be very difficult to change the ratios.
No doubt some system could be devised to convert the Comet dynamo drive to a chain system and use different sized sprockets to speed up the dynamo.
Matty
From what I have seen of both Miller and Lucas generators, I guess their output in wattage could be much the same, and though the Lucas is a more common item, it is also not hard to fit to a Vincent with the D type drive components. Where the lucas is superior to the Miller is in the commutator/ brush surface area. The lucas has much bigger brushes giving more contact on the comutator. When we had a Lucas on the test rig and loaded it up, the arcing at the comm was noticeable, but not excessive. Same test on the Miller, and the comm/brushes looked like an arc welder......The point most forget when placing higher than normal loads on a generator, especially when the battery is near flat...is that as the genny try's to run at a high output, the comm segments and windings get very hot. Generally where the solder connections from each comm segment to the wires in the armature, melt and is thrown out centrifugally. Thereafter the genny becomes useless. I've found both units in good serviceable condition and NOT overloaded in use, will work fine for years......but the Lucas is able to handle higher loads than the Miller.....Hope this is of help.....Greg.
I always had better luck with Miller.
Great stuff Greg, I have not checked, but was told the Miller had more commutator segments and different windings which made it better. But you have done some practical checks so it seems the Lucas unit is the best one after all under stressful conditions.
I qualified as an electrical/electronic Engineer many years ago and probably could have understood the theory of the generators then in detail - wave wound versus lap wound etc. But I'm afraid my brain has not survived in as good condition as the Comet I have owned since 1956, so I'll take your word for it, in preference to the opinions of others who advised me in the dim and distant past.
Just a little ironic story.
About 30 years ago a "friend" temporally fitted my spare pristine Lucas dynamo which I was intending to fit to my Comet, to his Rapide when the solder melted and threw the windings of his Miller. After a time he forgot he had my dynamo on his bike and sold it. When I enquired a few years later about my dynamo and how he had had his repaired he could not even remember the loan, but remembered he had binned an old wrecked Miller dynamo he found in his garage.!!!
Such is life - he is my son's Godfather after all, - but I still have the inferior Miller dynamo on the Comet !!!
Matty
I qualified as an electrical/electronic Engineer many years ago and probably could have understood the theory of the generators then in detail - wave wound versus lap wound etc. But I'm afraid my brain has not survived in as good condition as the Comet I have owned since 1956, so I'll take your word for it, in preference to the opinions of others who advised me in the dim and distant past.
Just a little ironic story.
About 30 years ago a "friend" temporally fitted my spare pristine Lucas dynamo which I was intending to fit to my Comet, to his Rapide when the solder melted and threw the windings of his Miller. After a time he forgot he had my dynamo on his bike and sold it. When I enquired a few years later about my dynamo and how he had had his repaired he could not even remember the loan, but remembered he had binned an old wrecked Miller dynamo he found in his garage.!!!
Such is life - he is my son's Godfather after all, - but I still have the inferior Miller dynamo on the Comet !!!
Matty
Hi Bob Collings
We all look on our bikes in different ways and I have always tried to keep mine as original as possible - so I run 6volts, bloody useless brakes, lowish compression ratio, cruise at around 65mph. 250 miles up to the Manx GP each year for the last 35 years with wellies and no leathers but unfortunately having to wear a helmet, etc. just to see if I and it can still do it. I don't use it at night very much however !!
If people want to convert to 12volts, fit disc brakes, bigger bores, higher compression ratios, self starters, centre stands, sticky tyres etc. it's fine by me -but I go modern for those comforts.
For more performance I have also had around 60 bikes in the last few years, mostly rebuilt for fun from salvaged write offs, including a Ducati, BMWs, Honda Fireblades, CBR 600s, my present HondaVFR 750, a CBX 6 etc all great fun with fantastic brakes and lights, but mostly I use the Vincent because I find it easier to ride and move around at 78 than the modern bikes, which are generally top heavy, high in the seat and have a terrible lock.
Matty
We all look on our bikes in different ways and I have always tried to keep mine as original as possible - so I run 6volts, bloody useless brakes, lowish compression ratio, cruise at around 65mph. 250 miles up to the Manx GP each year for the last 35 years with wellies and no leathers but unfortunately having to wear a helmet, etc. just to see if I and it can still do it. I don't use it at night very much however !!
If people want to convert to 12volts, fit disc brakes, bigger bores, higher compression ratios, self starters, centre stands, sticky tyres etc. it's fine by me -but I go modern for those comforts.
For more performance I have also had around 60 bikes in the last few years, mostly rebuilt for fun from salvaged write offs, including a Ducati, BMWs, Honda Fireblades, CBR 600s, my present HondaVFR 750, a CBX 6 etc all great fun with fantastic brakes and lights, but mostly I use the Vincent because I find it easier to ride and move around at 78 than the modern bikes, which are generally top heavy, high in the seat and have a terrible lock.
Matty
I'm very flattered that so many have found my Miller/Lucas conversion/regulator diagram of interest - I only hope that there are no errors on it. Please inform me if you find any.
The only addition I might make, is to flash the positive end of the field winding to the positive of a battery for a second or so BEFORE connecting the regulator. This should not really be needed if the dynamo had been working because the residual magnetism should be already correct, but can be done to make sure the dynamo is a positive one.
If your bike has positive earth you will need an appropriate regulator and to flash the field to the negative terminal of a battery,
The only addition I might make, is to flash the positive end of the field winding to the positive of a battery for a second or so BEFORE connecting the regulator. This should not really be needed if the dynamo had been working because the residual magnetism should be already correct, but can be done to make sure the dynamo is a positive one.
If your bike has positive earth you will need an appropriate regulator and to flash the field to the negative terminal of a battery,
Hi Matty,
I appreciate & understand your position regarding originality..it is a tough choice. I have changed to an Alton and put an LED kit in the tail light as well as an "O" ring chain..so outwardly from 15 feet away it looks stock, but has some modest alterations to improve safety (brighter lights), but I still stick stubbornly with the stock suspension, stock brakes ( albeit with alloy plates on the front), stock looking tires and original bore/compression ratio/carbs...
I appreciate & understand your position regarding originality..it is a tough choice. I have changed to an Alton and put an LED kit in the tail light as well as an "O" ring chain..so outwardly from 15 feet away it looks stock, but has some modest alterations to improve safety (brighter lights), but I still stick stubbornly with the stock suspension, stock brakes ( albeit with alloy plates on the front), stock looking tires and original bore/compression ratio/carbs...