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[Revband]

Well Rasp, you have been misinformed, fitting a capacitor in parallel will do nothing for the starting, all the old British bikes which had emergency start disconnected the battery from the circuit so the full output from the alternator was fed to the ignition with nothing being lost to the battery, look it up.

[Jamesy]

Revband am I missing something here? The output from an alternator is only available when the engine is running.So to start the engine an alternative source like a battery is required to start a motorcycle.

[Revband]

It only works on a kick or push start and the alternator supplied voltage is enough to have a spark, once the engine is running it is possible to increase the revs and switch to standard and the battery will then charge.

[Jamesy]

Got you.Thought about that but didn't think kicking bike over was enough for a spark.

[Revband]

It is when the battery is not taking any of the current, but you do have to kick very hard, a push start used to be in order but alternator output has increased, so possibly easier now?.

[Adrian]

Revband,



your statement " all the old British bikes which had emergency start disconnected the battery from the circuit so the full output from the alternator was fed to the ignition with nothing being lost to the battery, look it up." only applied to bikes fitted with the Lucas SIX volt alternator systems up to the mid sixties. My old BSA C15 SS80 had this, and I well remember the emergency start position, you had to switch back to the normal running position as soon as the bike fired up.



As soon as Lucas went from 6 to 12 volt systems however the emergency start position on the key switch and associated wiring were no longer there. ALL the output from the alternator now goes via the rectifier and regulator (Zener Diode in Lucas' case) ALL of the time. My BSA Victor workshop manual shows the '69 Victor Special with precisely this set-up, it also has a 2MC capacitor fitted according to the wiring diagram. So when I came to rewire my C15 for 12 volts based on the Victor/Starfire wiring diagram I fitted a 2MC capacitor (no battery) and it ran just fine.



Alan,



on post 1999 classic Bullets the AC lighting system for the headlight is totally isolated from/independent of the rest of the electrics. It makes no use of the battery, being direct lighting from the alternator's yellow and amber wires. Any changes to the DC side of the electrical system will not affect it.



A.

[Valsp]

Revband

The Interceptor has the capacitor fitted but no switching circuit to disconnect the battery

Perhaps you would now like to rescind your remark on 11th Feb "As usual on an internet forum bad advice is being handed out"

[Revband]

Adrian, You are absolutely correct, I was trying to establish that putting a capacitor in parallel with the battery will do nothing to make the bike start better, it is only needed if the battery is removed.

Valsp, Not only the Interceptor, many sports bikes of the era had a capacitor fitted, but perhaps not for the reason you think?, back then there were a lot of sports bikes used for daily transport and then raced on a weekend, the capacitor was fitted to enable the bike to be ridden to the race meeting the battery and any other unnecessary parts removed the days racing completed, parts refitted and the bike ridden home, Triumph even had a plug in headlight assembly for the same reason.

The capacitor is needed to smooth the voltage peaks from the alternator as these peaks can be of a high enough voltage to destroy the regulator/rectifier.

Rescind my remark re bad advice?, no definitely not as bad advice was being given.

[Alan R]

Hi Adrian and thanks for the update-----I'm now on my second Bullet '65 in the last 10 years...As you know these have both kick start and starter motor fitted as standard, and also includes the AC lighting for the headlamp........On the previous '65 bike I fitted the Bransden Power Box but kept the points and the battery "Just in case" ..... It was comforting to know that I had a capacitor back-up should the need arise..........I notice that the thread owner has yet to re-appear and answer the questions I put to him regarding his bike etc...Incidentally, assuming we have a kick-start only machine and fit one of these capacitors as a battery replacement then how do we have lights that work when the engine is stationary ??---or isn't that the case ??..........Meanwhile one or two contributors appear to be heating up a little.....Gents, at the end of the day it's only advice be it good or bad....It's up to the thread owner if they want to take it onboard, and surely not worth the typing effort to fall-out over ?? ( Climbs down off soapbox )..

[Revband]

Alan R, yes not worth the effort, you are right of course with a capacitor instead of a battery, when the engine stops the lights go out.a capacitor fitted across the battery will as I am sure you know will only be charged to the same level as the battery it is connected to, so therefore our op was misinformed and a flat capacitor is like a flat battery, it will do nothing to aid starting.I just find it hard to keep quiet when bad info is bandied about. I know, hat, coat.