Rectifier problems - AJS M14 CSR (1966)

Information relating to the Matchless G2 or AJS Model 14 250cc Lightweight
nfzdm
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Rectifier problems - AJS M14 CSR (1966)

Post by nfzdm »

Rectifier problems - AJS M14 CSR (1966)

I've just attempted to start my bike after 8 months without use. After connecting the battery for only a few minutes I could smell burning from the regulator.

I have assumed the regulator will need replacing but I thought I would check if anyone has experienced similar problems?
If the rectifier needs replacing I was thinking about upgrading the electrics to 12v. Would this help when staring the bike? It's very good exercise but very hard work...

Any advice would be really helpful. This is my first classic bike.

Best wishes

Damion
Steve S
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Re: Rectifier problems - AJS M14 CSR (1966)

Post by Steve S »

Hi Damion, I replaced my 6 volt electrics on my Model 8 with a 12 volt Wassell regulator (about £30) and a very small 12 volt sealed battery.

It has transformed the starting (only half the current going through the contant breakers) and the operation of the electrics generally as I can use cheap 12 volt LEDs.

You will need a 12 volt ignition coil and horn although for the latter I just wired in a low value resistor and it sounds fine.

Some will say that none of this is necessary and non original, but I value easy starting, good charging and reliability above all!

Steve S.
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clanger9
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Re: Rectifier problems - AJS M14 CSR (1966)

Post by clanger9 »

I have also upgraded my bike to 12v electrics in the same way as Steve (12v 3 phase Wassell regulator). I know it's possible to get 6v electrics working well, but I am not a fan as the spark always seems so weak compared to 12v. I also don't like the the way the Lightweight electrical system uses a resistor to limit the charging when the headlamp isn't on; anything amiss with the electrics and you end up with a boiled battery...

With the 12v electronic regulator I get a nice fat spark, have excellent (LED) lights and the bike starts first kick.

As Steve says, you also need to change the coil, the bulbs and the horn (if you want - you can get cheap 12v ones on eBay). Don't forget to fit a 10A inline fuse; in the event of a short-circuit, a modern 12V battery will happily put out enough power to start a wiring fire...
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1989 Moto Morini Dart 350
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Ozmadman
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Re: Rectifier problems - AJS M14 CSR (1966)

Post by Ozmadman »

I have kept mine as 6 volt and fitted a Areg rectifier/regulator from here http://www.norbsa02.freeuk.com/goffyelectrex.htm you get rid of the old rectifier and the resistor wire in the headlamp and with some simple wiring bob's your uncle. I even use an AGM battery so no more acid leaks
Paul
1960 Model 8
1974 Yamaha RD250B US Model 6 speed
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clanger9
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Re: Rectifier problems - AJS M14 CSR (1966)

Post by clanger9 »

Ozmadman's solution is the neatest if you want to stick with 6 volt: it solves all the overcharging problems and should be much more reliable than the original system.
1989 Moto Morini Dart 350
1993 Ducati 750SS
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Ozmadman
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Re: Rectifier problems - AJS M14 CSR (1966)

Post by Ozmadman »

This is where my Areg is fitted
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Paul
1960 Model 8
1974 Yamaha RD250B US Model 6 speed
nfzdm
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Re: Rectifier problems - AJS M14 CSR (1966)

Post by nfzdm »

Hi Steve and Paul,

Many thanks for the replies. After reading your advice I will be upgrading to a 12v system so I was going to order the following rectifier – could I just check that this would be okay?

Wassell Solid State Single Phase Regulator Rectifier, 12V, 160W - WW10123W

Looking at the dimensions of my current coil it seems a Lucas LU47276 12 volt coil would fit the bracket. Would this be okay?

Best wishes

Damion
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clanger9
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Re: Rectifier problems - AJS M14 CSR (1966)

Post by clanger9 »

Rightly or wrongly, I used a 3-phase rectifier/regulator. The alternator on my bike is a 3 phase one, so the 3 wires just go straight into the rectifier. It works perfectly.

Any 12v motorcycle coil should be OK (it should be designed for 12v operation without a ballast).

One tip for 12v operation: don't clamp the battery too tightly! I used a steel clamp (as per the photo) and the vibration caused my battery to go open-circuit. It could have been a faulty battery, but I have since replaced the clamping arrangement with a rubber strap and it's been fine.
1989 Moto Morini Dart 350
1993 Ducati 750SS
Steve S
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Re: Rectifier problems - AJS M14 CSR (1966)

Post by Steve S »

Hi Damion, I bought this from Ebay, 12V Wassell Solid State, Three Phase Rectifier Regulator - Max 190W - WW10124W. The one you quote is a single phase type and is not suitable; you need the 3 phase one.

BTW I have a new, spare 12v ignition coil I bought and did not use as when I took out the old one it was 12v!

You are welcome to have it cheap from me, send me a private message.

Steve S.
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Janet
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Re: Rectifier problems - AJS M14 CSR (1966)

Post by Janet »

Just to add a comment from one who knows very little and may have misunderstood what I was told by someone who does know electrics very well, your alternator has to work harder when electrics have been upgraded to a 12 volt system so it needs to be in tip-top condition.
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