Matchless G3L - Advance Setting During Normal Ride

Information relating to the Matchless G3 or AJS Model 16 350cc Heavyweight
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phenry
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Joined: Mon Jun 04, 2018 7:22 pm
Location: Tamil Nadu INDIA

Matchless G3L - Advance Setting During Normal Ride

Post by phenry »

Hello,

I have a question regarding the advance setting for a 1941 WD G3L.
I usually start the motorcycle a tad less than complete advance and during riding I set it half way through.
Of late I have been experiencing the problem of the bike misfiring unless I have to set it to complete advance even during normal riding.
I run a Micarb and would the reason be the carb settings? Please advice
Groily
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Re: Matchless G3L - Advance Setting During Normal Ride

Post by Groily »

Dunno about the carb, but for normal running the lever should be set to full advance.

It's in that position that the spark is the strongest owing to the way magnetos are designed. Apart from for starting, at tickover, and perhaps for slogging along at low revs in high gears heavily laden, full advance is the norm. A third to half retarded would be typical for starting.
There are going to be 20°-odd of advance/retard movement on the magneto, which is 40° on the crankshaft . . . over-generous really, as you don't need all that 99.9999% of the time.
. . . If the engine is meant to fire at, say, thirty-something ° before top dead centre fully advanced (and the timing was correctly and accordingly set) and you then run in the half-way position, you could be running as much as 20° off 'correct' in terms of the crankshaft degrees. Which at 'open road rpm' the engine probably won't like much!

When a mag starts to misfire except at full advance, it is often the first sign of impending failure. Although it needs a few more revs to make big sparks when retarded the sparks should be there all the same.
If, though, the bike is running badly with the lever retarded, that could just as well be simply because the engine needs more advance to run properly - ie that there is nothing wrong with the magneto.

Just my ha'pence worth, but before playing with the carburettor, I'd check the ignition timing from scratch, and go from there I think. If all is well in the sparks area but problems persist, then I'd start fiddling with the carb.
phenry
Posts: 50
Joined: Mon Jun 04, 2018 7:22 pm
Location: Tamil Nadu INDIA

Re: Matchless G3L - Advance Setting During Normal Ride

Post by phenry »

Thanks so much for the information. I have been so ignorant to even understand that the motorcycle is functioning properly.
It is good to ride when the lever is set to Full Advance but then when I alter it to half advance/retard there is misfiring.
So the retard set up is just for gradients or low gears.

Thanks and Regards
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clive
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Location: LONDON UK

Re: Matchless G3L - Advance Setting During Normal Ride

Post by clive »

Most if us use retard to start and then advance it once its running and leave it alone. Just occasionally tickover is smoother on retard but its a lot of faff and easier to leave it alone.
clive
if it ain't broke don't fix
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Rob Harknett
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Joined: Mon Jan 01, 1990 12:00 am
Location: ESSEX UK

Re: Matchless G3L - Advance Setting During Normal Ride

Post by Rob Harknett »

phenry wrote:Thanks so much for the information. I have been so ignorant to even understand that the motorcycle is functioning properly.
It is good to ride when the lever is set to Full Advance but then when I alter it to half advance/retard there is misfiring.
So the retard set up is just for gradients or low gears.

Thanks and Regards
These simple things are all explained in the bikes instruction book. The bikes workshop manual will go into more detail of settings. So when correct everything should go much as the books say they should. If not you then need to take into account any wrong parts that could cause problems. Also things like new types of Spark plugs and fuel. Look here for books on your bike. Books are first you should get before touching your bike. http://www.archives.jampot.dk
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