1954 350 idle

Information relating to the Matchless G3 or AJS Model 16 350cc Heavyweight
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Tazmantic
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Location: Oxfordshire UK

1954 350 idle

Post by Tazmantic »

Hi all this is probably a very open ended question but now I’ve done a few good runs on the bike I was hoping things would settle but at idle if you give it a rev it takes a while to drop back down to idle speed, the plug looks a good colour and I’ve checked round the carb for leaks an all seems fine so don’t think there is an air leak at the inlet so what else could cause this? Could worn valves or valve stems be the problem :?:

Cheers Neil
Everyday’s a learning curve.
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clive
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Re: 1954 350 idle

Post by clive »

Worn throttle slide. Air leaks round it. Usual symptom is as you describe, fast idle as you pull up and if falls back in time or often with a gentle blip of the throttle. New slide may fix it for a while but it tends the wear the internal body too.
clive
if it ain't broke don't fix
Tazmantic
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Location: Oxfordshire UK

Re: 1954 350 idle

Post by Tazmantic »

Cheers Clive, I do find I’m frequently playing with the idle speed screw to get the idle right and the carb on it was from flea bay and is a monobloc (not pre monobloc as it should be for that year) so could well be worn I will check it out, I do have another I can try.

Neil
Everyday’s a learning curve.
Yves.Astein
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Re: 1954 350 idle

Post by Yves.Astein »

If you want to make sure the idle mixture is ok, you might consider to get a “Color Tune” Sparkplug. I use it for tuning my idle mixture and it works. Just google it…
SPRIDDLER
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Re: 1954 350 idle

Post by SPRIDDLER »

Tazmantic wrote: Tue May 24, 2022 10:23 pm ....... the carb on it was from flea bay and is a monobloc (not pre monobloc as it should be for that year) so could well be worn
I've never bought a second hand carb on the basis that neither I nor anyone I know has ever had to replace a good one. ;)
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Tazmantic
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Posts: 388
Joined: Tue May 25, 2021 10:50 pm
Location: Oxfordshire UK

Re: 1954 350 idle

Post by Tazmantic »

Yves.Astein wrote: Tue May 24, 2022 10:29 pm If you want to make sure the idle mixture is ok, you might consider to get a “Color Tune” Sparkplug. I use it for tuning my idle mixture and it works. Just google it…
I do have one I’ll have to give it a go.
Everyday’s a learning curve.
Tazmantic
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Posts: 388
Joined: Tue May 25, 2021 10:50 pm
Location: Oxfordshire UK

Re: 1954 350 idle

Post by Tazmantic »

SPRIDDLER wrote: Tue May 24, 2022 10:38 pm
Tazmantic wrote: Tue May 24, 2022 10:23 pm ....... the carb on it was from flea bay and is a monobloc (not pre monobloc as it should be for that year) so could well be worn
I've never bought a second hand carb on the basis that neither I nor anyone I know has ever had to replace a good one. ;)
I’ve never thought of it like that, but it could be a spare they are selling :? but at the time I didn’t have one and the price was good so thought it was worth a punt :(
Everyday’s a learning curve.
Tazmantic
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Posts: 388
Joined: Tue May 25, 2021 10:50 pm
Location: Oxfordshire UK

Re: 1954 350 idle

Post by Tazmantic »

So had a check of the original slide and there did seem to be wear so I swapped it for another one I had which seemed a better fit and initial tests it seemed ok but now I find it ticks over at a nice speed, can ride off and sometimes when I stop it ticks over at the nice low speed then next time I stop it ticks over noticeably higher and just stays there, then next stop can be back down low again is this still a worn slide scenario?

Neil
Everyday’s a learning curve.
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