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 Jan 15, 2018 8:00 pm

Hi Mick,

I take your point, and will strip and inspect first, (I've ordered a repair kit with gaskets).
S*d's law has determined that the leaking has not happened since I reported it...

I just got a motorcycle bench, (Sealey MCW360), so I'm quite looking forward to working on a bike without having to crawl around on the floor!

Since it's coming upon to 200 miles since the engine was rebuilt (by the previous owner), I plan to combine the carb inspection with a quick once-over of cylinder base and head bolts, and also checking tappet clearances. I see in my '53 manual that the clearances should be "nil" with a "warm" engine. But mine will be cold when I get to that bit! Anyone know what clearances for a COLD engine? Or do I have to re-assemble and take it for a run before doing that bit?

Jonny

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Re: Matchless G3LS 1953 questions

Postby 56G80S » Mon Jan 15, 2018 9:07 pm

Personally after disturbing the head I leave the tappets a tad slack, short run. wait until I can just hold my hand on the barrel, pop off the tappet cover, adjust to nil (make sure on TDC easy with cover off) and cover back on.

I do have to say that my head is often disturbed.

Johnny B

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Re: Matchless G3LS 1953 questions

Postby Mick D » Tue Jan 16, 2018 9:45 am

Hi Johnny

Sounds even more like a sticky float valve then - now clearing with use.

A good strip and clean, blow through all the orifices, (don't be tempted to poke bits of wire through the jets, I use a bristle from a paint brush if required), and detailed inspection for wear using a magnifying glass. Look for wear especially on the seating / rubbing surfaces of the float valve 'needle' and the needle jet needle, (I'd replace the needle jet as a matter of course). Check the carb to head mating flange for 'flatness' using a straight edge, if it's bowed you can flatten it by lapping on a sheet of fine wet and dry fixed to a flat surface, (piece of glass or MDF etc.). Confirm the jet sizes are as per specification and rebuild / set up per the manual.

The throttle is bound to have worn over time but this can be compensated for by adjusting the needle position / pilot air screw and throttle stop screw.

If you have an understanding partner a cycle or two in the dishwasher brings up the alloy parts a treat ;)

Regards Mick

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Re: Matchless G3LS 1953 questions

Postby SPRIDDLER » Tue Jan 16, 2018 11:16 am

Jonny Astro wrote:I see in my '53 manual that the clearances should be "nil" with a "warm" engine. Anyone know what clearances for a COLD engine? Or do I have to re-assemble and take it for a run before doing that bit?Jonny

I have always set mine 'free to turn' with a cold engine and checked them later when warm. I can't recall ever needing to re-adjust them.
I poke badgers with spoons.

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Re: Matchless G3LS 1953 questions

Postby Jonny Astro » Thu Jun 21, 2018 8:10 pm

OK, I finally got around to re-torquing the cylinder head bolts and base nuts - just a small take-up, but glad I did it. Reset tappets - all good.

The original 76AE carb was clearly worn, which I think (hope) explains the erratic tickover. So in for a penny, in for a monobloc, new 1 1/16" instrument sourced. All pre-jetted as if for a '55 model when these were introduced. Lovely!

The new carb has an "O" ring on the mounting flange - this must be better than just the paper gasket that the 76AE had, but should I use a paper gasket as well as the O ring?

Jon

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Re: Matchless G3LS 1953 questions

Postby Mick D » Fri Jun 22, 2018 6:47 am

Hi

I believe the correct sequence of assembly is a 'paper' gasket between the head and spacer and an O-ring between the carb and spacer - no need for an additional gasket in my opinion.

Don't over tighten the carb attachment nuts, doing so risks distorting the mounting flange and introducing an air leak.

Regards Mick

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Re: Matchless G3LS 1953 questions

Postby Jonny Astro » Sun Jun 24, 2018 8:07 pm

OK, Monobloc fitted - absolute transformation! The tickover is now consistent and slow.... Doof Doof Doof !
It seems smoother on the road too, but maybe that's just my imagination?
Ironically it's not so easy to start when cold but I guess I have to learn the "secret" of this carb. When warm / hot I only need to prod the kickstart and it fires up.
So I now have a beautifully practical bike for those summer evening rides - I'm really chuffed.
So I'm on the details now: The footrests are both a bit bent - probably the result of some spills sometime in the bike's 65 year history. I guess I'll need some heat to help straighten them? If I take them off and mount them in a vice would a blowtorch do or do I need to be more careful?

Jon

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Re: Matchless G3LS 1953 questions

Postby Mick D » Mon Jun 25, 2018 7:12 am

Hi

Glad the carb produced the desired effect - re straightening the footrests, you'll need to get them cherry red where you want the bends to be so you'll need a good propane torch, (at least 3kw) or oxy/acetylene, it's also advisable to have a piece of tube about two feet long to slip over the rest which will allow more control over the bend.

If you don't have the means I'd suggest taking the bike to a blacksmith, if you pre-arrange your visit he should be able to sort the rests in around an hour and having the bike there to offer them up to will ensure a good result.

Regards Mick

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Re: Matchless G3LS 1953 questions

Postby raffles » Mon Jun 25, 2018 7:03 pm

Bent footrest I have always staightened them on the bike cold, just along tube fitted over the footrest and lift or press as reqired
best done on the centre stand with someone holding the bike.
Tony

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Re: Matchless G3LS 1953 questions

Postby SPRIDDLER » Fri Jun 29, 2018 5:41 pm

raffles wrote:Bent footrest I have always staightened them on the bike cold, just along tube fitted over the footrest and lift or press as reqired
best done on the centre stand with someone holding the bike.


I've straightened mine cold with a piece of tube over the peg and the flat fixing end jammed in the road drain iron grille.
Attach a piece of string in case it accidentally drops into the drain ;)
I poke badgers with spoons.

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