G3 1961 timing

Information relating to the Matchless G3 or AJS Model 16 350cc Heavyweight
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Ixy
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Joined: Sat Aug 03, 2002 1:00 am
Location: SOUTH YORKSHIRE UK

G3 1961 timing

Post by Ixy »

Can anyone advise me on the correct advanced timing position for my G3 1961. I'm not sure whether it should be 1/4" BTDC or 1/8" BTDC or something else?
I'm struggling to get it started, but think the coil is 'kaput' as I can hear a clicking from within the coil and the spark seems very intermittent if at all! It's got Boyer electronic ignition, (bike converted to 12V), everything else checks out OK. Can anyone recommend a replacement coil for use with this, should I just use a bog standard Lucas 12V oil filled 'car type' coil?
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Colin F
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G3 1961 timing

Post by Colin F »

Ignition timing for a "standard" 61 350 with engine number before 41575, my 61 has a engine number 40*** is 1/2" or 39 deg BTDC. This is with FULL advance [:)] With the ATC fully retarded the figure is 1/8" BTDC.

As you have a boyer, this replaces the ATC so would assume you have to static time with no advance [xx(] I suggest you check the installation instructions from Boyer [8D]

Again with a Boyer system sometimes you need to use their coils, otherwise there is a 12v PVL coil available which is more compact than the Lucas oil filled car type.

Charles
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G3 1961 timing

Post by Charles »

Using Boyer on my twin, I found the best method was to set the cylinder up at the correct 'distance' before TDC on compression and then set the Boyer up so it is just off the fully retarded position on the circular adjustment grooves. Get the engine running and then use the carb slide screw to give it a few revs or your throttle resistance screw etc. Then rotate the Boyer disc to advance the engine and the revs should rise to a peak. Then just back it off a touch from that peak i.e retard it a touch. Set the throttle and slide to your tickover revs and its done. I see no reason why this would not work for the single as well and I use the same method on the points on my single. Although this is empirical rather than the science, it works well on both mine (provided I have not trashed the engine by doing something stupid of course)

Good luck
Charles
Ixy
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G3 1961 timing

Post by Ixy »

Thanks Colin and Charles for the advice, I wasn't sure on the timing because the 1956 G3 manual says 1/2" BTDC but the 1957 to 1964 manual says 1/4" BTDC. My engine number is well before 41575 so I'll give 1/2" a try. It's just ironing out one more thing to try to get it started. I've had it running and been out on it a few times before with the Boyer, but I did a silly thing [:I] and wrapped the coil in foam rubber to hold it in the bracket and I think it's cooked it! It would go merrily for 20 minutes or so then conk out, coil boiling hot[}:)]
Now I think the coil has died, so I'll try another. Tried ringing Boyer today but couldn't get through so will ring again tomorrow. Once I get it running I can try your suggestions Charles.

Thanks,
Colin.
Ixy
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Joined: Sat Aug 03, 2002 1:00 am
Location: SOUTH YORKSHIRE UK

G3 1961 timing

Post by Ixy »

Got intouch with Boyer and they recommended a PVL type 12V coil, so got one of those, fitted it, set timing to 1/2" BTDC and ..... kick ..... kick ..... bike started, marvellous [:)]. Only thing is, checked output from regulator and 15V ! so I will have to get a new rectifier/regulator, (thats probably what's cooked the coil)! Can anyone suggest a suitable type?

cheers,
Colin.
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Colin F
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G3 1961 timing

Post by Colin F »

There are two types that are readily available. Boyer powerbox or Podronic.
Boyer is slightly more expensive, but has the advantage that there is a capicitor in the unit which allows for emergency starting with a flat battery, also allows the bike to run without a battery (not recommended for night time use as the bike tends to stall at tickover speed [:D]).
Otherwise for normally operation there is not much to chose between the two units as both operate on similar principles.
Dave
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G3 1961 timing

Post by Dave »

Colin,
You say that you checked the output of the regulator and it was 15V. What regulator have you got? If it's a zener diode then I would expect to see just over 14V if you're measuring the output without it connected to any load. What voltage do you see across the battery when it's connected and the engine is running with a few extra revs? Also I wouldn't expect an over-voltage of just a couple of volts to destroy an ignition coil. I ran a 12V system using a 6V coil for some time without any problems. It just used more current (Amps).
Just forget about spending more money on parts. If it fires up and runs OK then go and ride it for 30-40 miles. If all is still OK then I'd leave it at that!
Regards,
Dave.

Ixy
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Joined: Sat Aug 03, 2002 1:00 am
Location: SOUTH YORKSHIRE UK

G3 1961 timing

Post by Ixy »

The voltage across the battery with a few revs on is 15V 'ish. The rectifier/regulator looks like a 'heath robinson' type off an old car or something. It's got about 8 wires coming out of it, most of them shorted together and wrapped up with tape! Output to battery with lights on is about 13V, so I could ride with lights on all the time, (which is not a bad idea). But I think I'll invest in a powerbox, then it's all sorted.
Cheers,
Colin.
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