Matchless G3LS 1953 questions

Information relating to the Matchless G3 or AJS Model 16 350cc Heavyweight
Jonny Astro
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Joined: Sat Oct 07, 2017 4:13 pm
Location: BERKSHIRE UK

Re: Matchless G3LS 1953 questions

Post by Jonny Astro »

I've attended to most of the issues now - thanks to everyone for their advice.

Still got the carb problem though... To summarise:

It starts really easily without any adjustment of the advance/retard or tickling. Just wind the choke on and give it a purposeful kick - usually goes first or second go. Choke can be taken off almost immediately.

Once warm the idea speed was originally too low when riding it or when on the centre stand, but OK if on the side stand. I've adjusted the tickover up a bit and now it's OK when upright, and a bit quick when on the side stand. (Plug colour is text-book light tan).

But after about 30 seconds, in either position, it gradually dies, unless given a blip. Once blipped it's OK again for another 30 seconds, then dies again.

Once stopped, if on the side stand there is a slow drip-drip of fuel from the carb onto the dynamo cover. If righted or put on the centre stand, the drip stops.

Any ideas? Seems float-related to me, but before I 'go in' I'd appreciate any input from those who know more than me...

Jon
Mick D
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Re: Matchless G3LS 1953 questions

Post by Mick D »

Hi

Bit of a weird one this - my first port of call would be to ensure the float needle was clean and free to move within the float chamber cap and float valve assemblies.

May be worth starting the bike and gently tapping the float chamber with something that's not going to mark it and seeing if it still stalls after 30 seconds - if it doesn't it would point to a sticky float assembly.

Regards Mick
SPRIDDLER
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Re: Matchless G3LS 1953 questions

Post by SPRIDDLER »

Jonny Astro wrote: I've adjusted the tickover up a bit and now it's OK when upright, and a bit quick when on the side stand.
TBH I can't see how that's a problem. I've never left (needed to leave) my bike ticking over on the side stand. I get kitted up, get on, start it, check the oil return (sometimes) and ride away. When fettling I use the centre stand and if it falters I give it a blip.

I agree with Mick's suggestions re. the dripping.
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Cerberus
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Location: BERKSHIRE UK

Re: Matchless G3LS 1953 questions

Post by Cerberus »

I'm far from being an expert, but on my M16, fitted with a monoblock, if I leave it on the side-stand (to unlock and open the gate into the back of the house etc.), tick-over tends to accelerate, which implies increased fuel flow. However under those conditions, I do not get fuel dripping out of the carb. Your symptoms imply that the float needle is held slightly open when the bike is on the side stand, but the fuel is not getting into the inlet manifold as that would cause faster running. Identifying from where in the carb the fuel is leaking might give a clue to what the problem might be. I think I might be inclined to take the carb off, dismantle it and give all the passageways a good clean with carb cleaner and see what happens then.
croxford
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Location: Northamptonshire UK

Re: Matchless G3LS 1953 questions

Post by croxford »

I have found the champion plug is far better on my 16ms over the ngk plug any day

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clive
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Location: LONDON UK

Re: Matchless G3LS 1953 questions

Post by clive »

croxford wrote:I have found the champion plug is far better on my 16ms over the ngk plug any day

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Totally agree
clive
if it ain't broke don't fix
g5wqian
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Location: near swindon wilts

Re: Matchless G3LS 1953 questions

Post by g5wqian »

champion N5C plug is better , will burn off and run hotter .

re the primary cover , i have no sealant on mine and use the clubs foam rubber new type seal and it doesnt leak , but there are other holes in the rear of the backplate that could leak if not sealed .
it may not be the primary thats leaking though , could be gearbox if its a burman box , my burman leaks and took some time to work out where the oil came from as i was thinking it was the chain cover .

with the carb youll find it runs slow when cold and then speeds up when engine warms up , but you may well need to turn up the idle speed before starting , by around 3/4 turn and then it will idle cold , then when engine warms up back off the idle speed .
idle screw is easy to adjust externally if you have a monobloc carb , its the bigger screw facing downwards .

putting bike on sidestand makes mine run bad unless idle speed is high , it will usually stutter and conk out if left on sidestand but runs ok with the centre stand .
you may be able to adjust the float level or check it , if its a pre monobloc carb it may be easier to check it out , but also remember to check float bowl for rusty sediment and clean out if necessary .
i have an old senspray carb on my older bike and the very fine sediment of rust from inside the tank gets past the filter and now and again it will conk out , so i will have to take the float out and clean bottom of the float bowl of sediment before it goes again ..


be carefull leaving bike running as if mine revs above a certain level it will move backwards on the stand .

you really do need to use the retard when starting or some time youll get a nasty kick back .

ammeter -- depends on whether it is a 8-0-8 amp type and what the dynamo is , but dynamo may well be a 60w type i guess , and if the ammeter is a good old one or a new one made recently .
i had to replace my ammeter when the moving coil fell apart , so i put one of the new lucas ones on there , but at same time id had my dynamo off and rebuilt it due to oil getting in from the timing cover on my particular model .

did have to swap wires on ammeter round though as the new one is wired opposite way round to previous one .

running with the 35w bpf bulb i find ammeter drops minus 4 amps at idle when light is on and when bike revs up it goes to zero and into the + side , and with light off it goes to plus 4 amps charging .

i did reflash the polarity of dynamo after rebuild , easy job just disconnect the negative wire from battery [the non earthed one ] if its positive earth .
remove the wires from dynamo socket and with a piece of wire connected to the -ve battery terminal you flash other end of wire on the F terminal of dynamo a few times for a second or so each time , it should make a flash each time you swipe the bare end of wire over the F terminal , this is then polarised for pos earth.

with the new lucas ammeter i found it moves slowly compared to the old ammeter i had , and because i rebuilt the dynamo i did flash it 2 separate times and had to put a fair load [35w bulb] on it before it would charge to a higher degree although it does have new brushes in which may have required a run up for a few minutes before bedding in to the armature .
seems to work fine now .
i was running a LED headlight bulb but after putting the filament type back in again it looks like i have a better pattern with the old style bulb so am going to try it out for a while and see which is better for me at night .
i dont do much night riding but the last time i rode from oxford to swindon in the dark it was not the best of trips with the LED light not giving me the type of beam i should expect , and i had played with a couple of headlight units and found the lucas one to be best pattern with the LED but never tried the old bpf bulb in the new lamp so will give that a go .

i do ride down near you neck of the woods when the weathers better , usually around chilton foliat and hungerford and newbury area , quite good lanes around there to have a look around and good views .
if you go up above ramsbury you can still get on the old wartime airstrip and have a quick blast along it , missing the pot holes as you go .

regards
ian
Jonny Astro
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Location: BERKSHIRE UK

Re: Matchless G3LS 1953 questions

Post by Jonny Astro »

Further to the idling issues discussed before -
I'm coming to the conclusion that I have a worn carb. I'll strip and check it before making any major decisions of course, but if it is indeed worn, it seems there are a few options:
1/ Buy a new carb 76AE complete from Burlen (£300!)
2/ Re-sleeve the old one - lower cost but indeterminate turnaround time, and spring is on the way!
3/ Can I fit a monobloc? Available from Burlen for about half the cost of the 76AE. Presume the 1" is the way to go - are the mounting holes on the same pitch?
Jonny
raffles
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Re: Matchless G3LS 1953 questions

Post by raffles »

What ever carb you decide to use (yes a monoblock will work beautifully) you will find the best deal with the club.
Tony
Mick D
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Re: Matchless G3LS 1953 questions

Post by Mick D »

Hi

Strip and inspect first - the conditions you detail, (dripping and cutting out after 30 seconds), are not symptomatic of a worn throttle. Whilst a new carb or re-sleeve would undoubtably be a great improvement I'm pretty sure your existing carb could be made perfectly usable with a little TLC.

Have you tried tapping the float chamber as I suggested?

Regards Mick
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