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Very poor rear lighting
Second Gear User
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August 23, 2021 - 8:52 pm
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Tried searching the faq's... nowt.  With my 59 D7's light switch to the right, I have to have fairly high revs to get headlight... and the rear bulb is almost non existent. Also there is no brake lights at all.   With the switch to the left, the front pilot light is fine but no brake light.  I can't find anything useful in my manual or handbook...  Any advice please.

Lancashire (A chip shop somewhere near Preston)
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August 23, 2021 - 9:44 pm
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1st thought is that maybe your flywheel needs re-magnetising. I might be wrong. Sunny is the best person to offer an insight on this sort of problem.

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August 23, 2021 - 10:35 pm
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There is only a finite number of watts available from a D7’s generator. If a previous owner has fitted too high a wattage headlight bulb, there will be insufficient power to drive it, and consequently not enough left to illuminate the tail lamp either. You need a 25/25 W headlight bulb as a maximum really. 

The brake light is powered from the battery, and should work without the engine running, or the ignition on. 

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August 24, 2021 - 9:39 am
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hi  Bob   the  D 7 have  odd  eletrics      as  you  will  see  ,   it  sounds  like  your  D7  has  mix  of  D modle systems    so its   inporant  to  identify  wot  generator   and  harnes   it  has thay   as  dont  mix   well    so  please  read      DUCON   tips  in    F A Q     and  search  [ top left ]  the  SPEC    number  thats  on the generator  and  use  the   Privet  Mesaging  system    we  have   as  a  club  to  reach   me    

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October 15, 2021 - 12:33 pm
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Have you owned the bike long, and has it always been like this ?

On my project D1 I wired a loom into a period single ignition/ light switch, and discovered the same 'features' you describe when first operating the nonstandard  Switchgear I had installed.

The 'strange' functionality was traced to an incorrect cross wiring connecting issue I had made, and by junking the pattern D1 switch. So might be worth you checking the condition of your switches terminal end connections, and the loom against a wiring diagram. 

I wired negative earth in the end, but lighting performance was improved by cabling in both positive and negative wires to the lights,  and in my case all those earth's were run & met at a single frame point, under the saddle.

A mate demonstrated the lighting improvement to me by showing a ' before and after,'  when I assumed there would be no improvement achieved by running power cable to the lights, and trying to complete the circuit via the frame locally.

Central France
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October 15, 2021 - 5:13 pm
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BobLowe said
Tried searching the faq's... nowt.   

Have you looked elsewhere? ** Please log in to view **

Is it magneto or coil ignition?

Don' forget it's a 62 year old bike with a generator giving about 50 Watts when in top form. Do you have all original specification bulbs fitted? Otherwise you may be overloading the system. Most problems have been discussed, though the D7 has a variety of wiring options so you need to be sure of what you have.

You also need to know how you should be operating it.

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October 15, 2021 - 5:36 pm
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Dare I mention LED's – good quality LED 'bulbs' are available from Classic Car Leds – lots of brightness from negligible current, compared to filament bulb equivalent. Positive and negative earth, 12V and 6V, and maybe even bi-directional, at least hr sold me a couple like that.

Mike H --

Murphy's 4th law of motion states that any small object that is accidentally dropped will immediately hide itself under a larger object.

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