Matchless G3LS 1953 questions

Information relating to the Matchless G3 or AJS Model 16 350cc Heavyweight
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Re: Matchless G3LS 1953 questions

Postby Jonny Astro » Mon Aug 20, 2018 2:28 pm

Me again!

My 1953 G3LS is running really nicely, especially since fitting the monobloc carb. Just approaching 500 miles since it's rebuild by the previous owner, so I thought I'd give it the once over - change the oil, check the timing, etc. Questions:

1/ Do I need to drain the sump or would it be OK to just change the oil in the tank?

2/ Will I need to use a new primary case seal after checking the chain or are they re-useable?

3/ I gather that ignition timing is 7/16" or 1/2" BTDC, but given that the spark plug hole, through which I will poke my depth gauge, is at about 45 degrees to the stroke axis, do I need to do some trigonometry or is that measurement taking the angle into account?


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Re: Matchless G3LS 1953 questions

Postby Mick D » Mon Aug 20, 2018 3:47 pm


1/ I'd drain the sump too - it will allow you to ascertain there are no horrors lurking - if you see any metallic debris in the sump oil it would be cause for further investigation.

2/ I'd only check / adjust the chain tension - doesn't your chain case have an inspection port to facilitate this? If this is the gasket to which you refer, I'd have one standing by but have a go at re-using the original.

3/ The dimensions are 'vertical' as I understand - just rest your depth gauge on the inboard side of the plug hole and keep it vertical-ish and you'll be OK.

Regards Mick

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Re: Matchless G3LS 1953 questions

Postby spookefoote1956 » Fri Sep 07, 2018 6:51 pm

Try cleaning the carb with some wynns carb cleaner. Sorted mine out a treat.
हरे कृष्ण हरे कृष्ण
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All my bikes are original........ to me!

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Re: Matchless G3LS 1953 questions

Postby Jonny Astro » Mon Mar 04, 2019 3:36 pm

My 1953 G3LS has done about 500 miles now since it was rebuilt by the previous owner, and I finally got around to giving it a "light service". Changed the oil in the tank and sump - no nasty surprises.
Pulled the primary case cover too - the primary chain tension felt spot-on, but the dynamo chain was VERY slack. Eventually worked out which was the dyno clamp nut and rotated the body to find the best adjustment.
So far, so good - now to replace the cover! It had a modern-looking rubber seal fitted but this was leaking very slightly, so I ordered a new one from the club shop - it's different. The new one's material is less dense (neoprene?) and the "T" section does not follow the contours of the case or cover so closely.
Main issues are that instead of being a closed loop the club seal is just a straight length, (i.e. not "joined up" like the one I took off) and the part of the seal's section which will be in compression seems to be thicker.
Just cut to length and have the ends meet up along the top edge? Hope the clamp will keep the oil in?
Do I need to "adjust" the amount by which the main retaining nut compresses the new seal? Or will it's softer density mean I can just tighten it like it was before?

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Re: Matchless G3LS 1953 questions

Postby dave16mct » Mon Mar 04, 2019 4:10 pm

Put the join at the top, you may need to shorten it a bit. Add a couple of washers behind the centre stud.

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Re: Matchless G3LS 1953 questions

Postby 56G80S » Wed Mar 06, 2019 12:07 pm

"just rest your depth gauge on the inboard side of the plug hole and keep it vertical-ish and you'll be OK."

Mick's spot on. Personally, I use a length of stiff wire (with the top bent in such a way that it can't fall in) and put two small nicks from a triangular file once I've marked my TDC with sharp pencil.

On the dynamo, hope you haven't overtighten the bolt on the strap, it will bend the rod between the engine plates at the bottom part of the strap. It's equally important to re-check for tight spot once you think you've finished. Be sure that the primary and dynamo chain runs are lined up properly with the engine sprocket; I experienced (long ago) the result of the chains clashing and it's not nice. Others will disagree about it's value, but thanks to a drawing by Don Madden, I made and used the "flat steel" strip that locates the dynamo and stops it wandering into the chaincase. I think Club spares has these now.

But, I recall the comment by Biscuit (a now deceased but knowledgeable Club member) who said that generally more problems are caused by chains being slightly tight than ones being slightly slack. It's easy to bend the dynamo armature or wreck the small bearings.

Johnny B


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