Author Topic: My new Douglas Mk-V wont light up  (Read 3511 times)

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Offline Jeffbo1

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My new Douglas Mk-V wont light up
« on: 01 Dec 2012 at 15:43 »
I just took receipt of a Douglas Mk-V from Australia....Came by boat of course and was well packaged and in great shape when it arrived...I got it out of it's crate and added fuel and oil and she fired right up...but there was no lighting...not even the horn worked...now I know that some sort of metal preservative was used on the bike before packing, but I don't know what I am missing...battery is up etc....any thoughts?

Jeff

Offline eddie

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Re: My new Douglas Mk-V wont light up
« Reply #1 on: 01 Dec 2012 at 17:53 »
As there are no lights or horn, it sounds like no earth or poor earth connection to the battery. The horn usually has it's own connection direct to the battery due to it's relatively high consumption. The lights are wired through the ammeter and main switch - so, as neither work, it is most likely an earth fault. Also, if there is an earth fault, with the engine running no charge will show on the ammeter, but the dynamo may be giving off enough power to run the lights. As an initial check, connect a bulb across the battery and see if it lights. If it does, connect it to the live side of the battery and any earth point on the engine or frame - if it lights, the battery earth is OK and the fault lies elsewhere. If the bulb does not light at all, the battery could be dead and not giving enough power to excite the dynamo into producing any charge. Try substituting the battery, but before starting the engine, momentarily bridge the live side of the battery to the 'F' terminal on the dynamo - this will polarise the dynamo to suit the polarity of the battery (after laying idle for some time, dynamos often loose their residual magnetism, so dont produce enough power to charge the battery).

  Hope this helps,
                           Regards,
                                         Eddie.

Offline Jeffbo1

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Re: My new Douglas Mk-V wont light up
« Reply #2 on: 03 Dec 2012 at 02:00 »
Hey Eddie and thank you for the information, very helpful indeed! After spending some time cleaning her up and getting some run time on the engine, all lighting is working now....I have a couple of other questions which come to mind, is that now that I have the lights working, and the battery charged, I am not seeing a brake light illuminate when applying the brakes....it lights up with the head light but does not get brighter with the application of the brakes...Im not even sure if it has a brake light switch as I haven't located that as yet...also, can you recommend a brand, and heat range of spark plugs for this bike? I really want to freshen her up...many thanks again!

Jeff :)

Offline Jeffbo1

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Re: My new Douglas Mk-V wont light up
« Reply #3 on: 03 Dec 2012 at 02:03 »
Ooop I saw your previous reply to another owner regarding the spark plugs Eddie,  NGK B7HS.....I'll look for these...Jeff

Offline eddie

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Re: My new Douglas Mk-V wont light up
« Reply #4 on: 03 Dec 2012 at 06:29 »
Jeff,
       When the Mk V was supplied in the 1950's it had no stoplight (as it wasn't a legal requirement in those days). Any subsequent fitting is therefore likely to have been added by a previous owner - so there could be a variety of setups - the most common being some kind of pull switch attached to the rear brake pedal and wired direct to the live side of the battery. Some owners have even tried using the compression switch in the front brake cable (as favoured by the Triumph/BSA group in the late 60's).
     Regards,
                  Eddie.

Offline Jeffbo1

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Re: My new Douglas Mk-V wont light up
« Reply #5 on: 03 Dec 2012 at 15:54 »
Thank you Eddie, I wondered about that as there is no switch anywhere that I can find....in fact the taillight wire doesn't even pass through the rear fender to the lamp as there is no hole....it simply follows the curvature of the fender mostly underneath then comes outside around the lower reach of the fender to the light....seems primitive but hey, it works!  thanks again...Jeff

Offline Jeffbo1

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Re: My new Douglas Mk-V wont light up
« Reply #6 on: 04 Dec 2012 at 20:17 »
Finally discovered the fault with my lighting system...turns out the switch on the headlight is a bit doggy and a slight wiggle either solves the problem or causes it as I play with it....so the switch needs to be replaced....finally the culprit has been found