Hello
I have recently bought A BSA B40 1962. I am having troubles with the ignition, the bike runs if I keep the revs up on the throttle.
It looks like I am missing a condenser within the distributer comparing it with the manual. Is this the case? what does it do?
Thank you
Clive
Yes - the condenser should be bolted on to the threaded pillar at the top and connected to the input terminal on the left. The condenser stops all the energy stored in the coil arcing across the points when they open. Without it, most of the energy is lost in this way rather than generating a high voltage which discharges across the spark plug gap.
Thanks it looked like there was something missing. The bike fired up but would not run.Does anyone know which condenser I need . Save me ordering the wrong one. Thanks again.
This is the type you require but try contacting one of the UK suppliers to see if they have one (Feked, Dragonfly, Burton Bike Bits, etc):
https://www.ebay.co.uk/itm/NOS-Lucas-421327-Condenser-1960-1962-Triumph-w-Lucas-15D1-Distributor/322873274942?hash=item4b2cbf323e:g:lUcAAOSwA~VaBL1N
I would be suprised if the bike would run without the condenser fitted.
It could be remotely mounted - it is just connected in parallel with the points - between the input terminal to the distributor and earth. It was not always easy to find the appropriate one to fit inside the distributor and owners improvised. Follow the wires from distributor and you may find it.
I think the bike will still run without the condenser and will probably do what you've experienced because the coil energy lost across the points will reduce with higher revs - this is simply because the time the point's gap is very small (which is when the energy is lost) will reduce. The condenser needs to be mounted as close to the points as possible - if it was mounted near the coil it would still probably result in arcing across the points and poor running.
Bikes fitted with the 6CA points assembly, fitted to BSA unit singles and twins from around 1967, had remote mounted condensers - there was just not enough room for one on the new design points assembly.
Thanks for your comments and knowledge .ive had a look and there is no condenserI'll source one from somewhere.
Hi, - interesting. As you know I'm having misfiring problems. My condenser is fitted remotely near the coil. Please explain why it needs to be near the points - I haven't heard this before.
Many thanks,
Phil
Hello. I've put a condenser in the distributor. The bike will only run if I keep reving the engine and there's quite a bit of arching at the points,? The bike also misfires quite a bit ?
If you didn't have a condenser connected before, you would have got a very weak spark. If you've now fitted a condenser and it hasn't made a difference to how the engine runs, I would double check the condenser is doing what it should be. To check, you can do the following:
Take out the plug and connect it to the HT cap and earth the threads against the bare metal of the engine. Rotate the engine so that the points are closed and switch on the ignition. If you then open the points with a screwdriver, or preferably something made of plastic, you should then get a spark at the spark plug. If you disconnect the condenser it will change the spark produced from a healthy one to a weak one which may be difficult to see. If disconnecting the condenser doesn't produce this change, it's not doing its job either because it isn't connected correctly; it's the wrong polarity condenser or it simply doesn't work.
Quote from: AWJDThumper on 29 Jun, 2018, 13:46
If you didn't have a condenser connected before, you would have got a very weak spark. If you've now fitted a condenser and it hasn't made a difference to how the engine runs, I would double check the condenser is doing what it should be. To check, you can do the following:
Take out the plug and connect it to the HT cap and earth the threads against the bare metal of the engine. Rotate the engine so that the points are closed and switch on the ignition. If you then open the points with a screwdriver, or preferably something made of plastic, you should then get a spark at the spark plug. If you disconnect the condenser it will change the spark produced from a healthy one to a weak one which may be difficult to see. If disconnecting the condenser doesn't produce this change, it's not doing its job either because it isn't connected correctly; it's the wrong polarity condenser or it simply doesn't work.
Excellent advice .
I'll give that a go thanks
I have been using the Brightsparks Easycap condenser in my bikes and have been very pleased. As well as beening solid state they are very compact.
http://brightsparkmagnetos.com/easycap/
I think the jury may still be out on whether these ceramic multilayer capacitors are reliable in the longer term for this type of application. Brightspark's recommendation for replacing them after 4 years or subjecting them to high voltage capacitance testing after 4 years and every year thereafter doesn't inspire a huge amount of confidence, especially as normal electrolytic capacitors last many years longer. For magneto use, it is a different matter because they provide a very neat way of accommodating the capacitor.
Here's a photo with new condenser. I tried the above with plug out and opening points. As you said difficult to tell wether spark is better or not. How can a condenser be wrong polarity?.and I presume it's correctly fitted.
Your very first photo seems to show a black sleeved wire connected to the distrubutor (this is the one I though might be connected to a remote condenser). This wire is not shown in the second photo??
Running without condenser would result in burnt points - are they in good condition?
Sorry - my use of English wasn't clear enough! I meant that without the capacitor, you might find it difficult to see the spark. The difference with and without the capacitor should be totally obvious - in the former case, you will see (and hear) a strong bright blue spark; in the latter case, you might struggle to see the very weak spark. If you can't see a difference then it suggests the capacitor is not doing it's job.
This assumes that the coil is working correctly. If there is a problem with the primary winding (eg partially shorted), it might not generate the correct HT voltage across the spark plug. If you have a digital voltmeter, you can measure the resistance of both the primary and secondary windings. If ok, they should be about 2 Ohms and 10,1000 Ohms, respectively.
The capacitor used is electrolytic which will normally only work properly when connected the right way round. On this basis, if you have a capacitor designed for a -ve earth system, it might not work with a BSA +ve earth system.
Quote from: phill on 24 Jun, 2018, 12:08
Hi, - interesting. As you know I'm having misfiring problems. My condenser is fitted remotely near the coil. Please explain why it needs to be near the points - I haven't heard this before.
Many thanks,
Phil
The condensor does not not need to be near the points, it needs to be electrically connected to the points-coil connection. Fitting the condensor near the coil is better because it is not getting cooked by engine heat
In a brand new bike it doesn't matter where the capacitor is. The potential problem is with older bikes and corroded earth contacts and degraded earth return paths. The points serve two purposes in a coil ignition system. When they open, they interrupt the current though the primary coil which then generates the HT voltage across the spark plug gap. However, when the points close they also perform the important task of shorting out the capacitor and reducing its stored charge to zero. With the capacitor close to the points, this will always happen. However, if the capacitor is mounted near the coil, there is a risk of a corroded earth connection between the capacitor and the points housing and this may result in the capacitor not being properly shorted out and discharged when the points close. If this happens, the quality of the HT spark may degrade and more arcing across the points may occur. It would be more of a problem with a 6V system rather than a 12V system.
Tested coil got readings of primary 3.9 ohms secondary 4400 . Also measured ht lead and got 12000 ?
With a copper cored HT lead you should be getting a zero reading - that is just the cable not including plug cap.
If your HT is a carbon cored resistive type then replace with copper cored.