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Well running engine suddenly cut out - any suggestions why?
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MartinFarrell
Kingston Surrey
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October 11, 2020 - 8:59 pm
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Hello.  I just got my 1968 D14 running (sealed tank, clean carb).  Starting and engine running spot on.  Two miles down the road it suddenly stopped. Push home. 

There's no spark from plug or end of HT lead. Checked all wires as best I could, visual inspection of points (recently adjusted and unchanged), coil, condenser, rectifier, (fully charged) battery connections.  All looked good. All but rectifier replaced in the last couple of years and low mileage since.  

I've run out of guesses about what it could be. Any suggestions?  

Thanks

Martin       

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mikef
Chatham Kent
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October 11, 2020 - 9:26 pm
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Hi Martin.
         Sorry to hear of your plight. The good thing is that you are well on the way to finding the fault. You know that there is no spark.
The first check that I would make is to check the voltage on the coil with the ignition switched on. The green wire to the ignition coil should have battery voltage on it. Does it ? If not then you need to check out the wiring from battery through the ignition switch to coil. Could be something as simple as the switch socket slipping down and those switches can go bad.
The second check is to see if the maroon wire to the coil switches between ground and battery voltage as you rotate the engine, that will check out the points and the wiring to the points.
The above two tests will give you a lot of information as to where the fault lies.
Visual checks will probably not help much, time to get out the voltmeter.
Let us know how you get on.
               Mike.

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Unitminor
Norfolk
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October 11, 2020 - 9:27 pm
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I would change the condenser  

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MartinFarrell
Kingston Surrey
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October 11, 2020 - 10:29 pm
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Thanks for these speedy (lots speedier than my D14 right now) and very helpful responses. Ignition switch - that's interesting.  I did look at it and see the clip is not holding it up but still no spark even when I push it up firmly. Busy with other (much less important!) things in the next few days.  I'll take a look soon and report back 🙂

Condenser was new about a year ago and since then its not been running much (sorting dirty tank, carb and being lockdown).  Could it just suddenly fail like that?     

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Isbfan
Mickleover, Derby
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October 12, 2020 - 11:08 am
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Check the high tension lead is not loose in its seat in the coil. Happened to me..

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AdrianS
Harlaston Staffs
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October 12, 2020 - 11:43 am
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New condensers can fail! Especially ones made in the Far East!

As said, no spark = no electricity so there is a break in the chain somewhere.

Start with the battery, then check voltage at coil as previously been said. Check continuity of wire from coil to points and check they are working properly. Check Ht lead is seated at both ends.

if you haven’t got a voltmeter then a bulb with some wires connected to it can be used. 

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slumanbantam
Bristol
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October 13, 2020 - 2:42 pm
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My new condenser lasted about a month with only about 20 miles being ridden since having it fitted, I experienced a similar problem to yourself, fitted new condenser and away we went.

1968 BSA Bantam D14/4

2018 Husqvarna Vitpilen 401

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Unitminor
Norfolk
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October 13, 2020 - 2:54 pm
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New coils and condensers have not got a good reputation for reliability . I use lucas condensers from the 70 s that were removed from cars to have updated ignition fitted .

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Number6
Lincolnshire
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October 13, 2020 - 8:14 pm
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Unfortunately there is a spate of this. I read about it frequently on the Moto Guzzi forums I'm on. My pet theory is that because modern car and bike manufacturers have ceased using them long ago, the standards have dropped and nobody is testing them properly. http://livinginthepast-audioweb.co.uk/imagex/misc/sad.gif

In the meantime, google for Thorcap  ...

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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sunny
Norfolk
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October 15, 2020 - 8:19 am
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thers  no  truble  geting  mine or  escrt  lucas  cerpasitors   in  you  local  car shop  and make  a  clip to  hold it  iv  done  it for  years 

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MartinFarrell
Kingston Surrey
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October 18, 2020 - 9:56 pm
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Hi guys, Bantam is running Wow 🙂

I have had a full week and also was a bit nervous of attempting all the good advice you've given me - I was afraid it would not work and I'd still have a dead bike.

I didn't know quite where to start so I started at the top. I checked the green wire to the ignition coil and there was no battery voltage.  I checked everything and found that the problem was a faulty connector in the middle of the wire going to the switch (looked like it had been there since 1968!)  I put a new connector and after I charged the battery there was a spark and ... blast off.  Running!

I had assumed that a new condenser would last for years.  With your advice, I'll keep an eye it.

Thank you guys.  Much appreciated.       

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cocorico
Central France
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October 19, 2020 - 7:31 am
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MartinFarrell said
...a faulty connector in the middle of the wire going to the switch...I had assumed that a new condenser would last for years. ..

Congratulations! It's always worth checking connections and switch contacts, especially when they are as old as those on Bantams. As for capacitors, you'll find countless posts on them across the forum. For myself, I have a capacitor from a 1952 D1 and a 1956 D3 which still work fine, though I prefer to make my own from modern ceramic disc capacitors (also on the forum).

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