Carb question.

Information relating to the Matchless G2 or AJS Model 14 250cc Lightweight
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ColourNcoat
Posts: 140
Joined: Thu Oct 22, 2020 8:07 pm
Location: Monmouthshire UK

Re: Carb question.

Post by ColourNcoat »

Hi All,
After carrying out some adjustments to the ( home made ) oil screw i did manage to get an improvement.
She is running a bit better and now idling. I have said previously that she is smoking but not extremely. When I ran it yesterday
it was cutting out so afterwards I removed the plug and it was oily black, so this is what directed me towards the inlet valve oil control screw.I didn't think it was smoking that bad to cause this much of a problem but its heading this way. I ordered a new oil screw last night as there wasn't one on the engine.
Spriddler put up a picture of the item in question so I made one close to picture.
I can't thank everyone enough for all the help. As soon as the new oil screw comes it will be fitted and hopefully it shows any underlying issues
with the carb.
Regards
Roger
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dave16mct
Member
Posts: 3234
Joined: Mon Jan 01, 1990 12:00 am
Location: LANCASHIRE UK

Re: Carb question.

Post by dave16mct »

When you get the new oil screw, screw in and just then turn out just off it's seat. The manual states 1/6th of a turn out but many find this too much. I've a feeling this has been part of your problem all along.
PS when a mate arrived at the IJR in Italy he had a twig sticking out of the rocker box as he'd lost the adjusting screw. He found a twig in a hedge and whittled it down to fit! I've a picture somewhere.:lol:
Dave.
ColourNcoat
Posts: 140
Joined: Thu Oct 22, 2020 8:07 pm
Location: Monmouthshire UK

Re: Carb question.

Post by ColourNcoat »

dave16mct wrote:When you get the new oil screw, screw in and just then turn out just off it's seat. The manual states 1/6th of a turn out but many find this too much. I've a feeling this has been part of your problem all along.
PS when a mate arrived at the IJR in Italy he had a twig sticking out of the rocker box as he'd lost the adjusting screw. He found a twig in a hedge and whittled it down to fit! I've a picture somewhere.:lol:
Dave.
Brilliant ;)
He obviously thought it Wood work and that's what you call thinking outside of the box :D
It is a shame it's taken so long to find or see the possible problem. I've seen cars with plumes of smoke and they still run :shock:
I so appreciate everyone's help and kindness with my first British project bike.
Let's hope it is the problem :beer:
Roger
ColourNcoat
Posts: 140
Joined: Thu Oct 22, 2020 8:07 pm
Location: Monmouthshire UK

Re: Carb question.

Post by ColourNcoat »

An update on possible findings,

Today the oil control screw came today, fitted it and set oil feed as been mentioned.
A tiny bit better but still problem of fouling the plug.
I stripped the carb down yet again and painted blue dycom on tip of mixture screw and found where it was seating and turned out 1 1/2 turns out.
Ran it again and still no improve ment.
After double checking everything I noticed a very small smear of oil around the head gasket area. I think I have finally come across my problem.
Tomorrow I shall remove the head gasket and replace with the new copper one issued as replacement.

The conclusion is it could be the head gasket passing a small amount of oil into the combustion chamber fouling the plug.
Regards
Roger
SPRIDDLER
Member
Posts: 8542
Joined: Wed Sep 01, 2004 1:00 am
Location: WEST SUSSEX UK

Re: Carb question.

Post by SPRIDDLER »

ColourNcoat wrote: After double checking everything I noticed a very small smear of oil around the head gasket area. I think I have finally come across my problem.
Tomorrow I shall remove the head gasket and replace with the new copper one issued as replacement.

The conclusion is it could be the head gasket passing a small amount of oil into the combustion chamber fouling the plug.
Regards
Granny.......eggs, so forth, but be sure to anneal the copper gasket - even new ones can have been stamped out of age hardened sheet.
'There is a tide in the affairs of men
Which taken at the flood............'
ColourNcoat
Posts: 140
Joined: Thu Oct 22, 2020 8:07 pm
Location: Monmouthshire UK

Re: Carb question.

Post by ColourNcoat »

SPRIDDLER wrote:
ColourNcoat wrote: After double checking everything I noticed a very small smear of oil around the head gasket area. I think I have finally come across my problem.
Tomorrow I shall remove the head gasket and replace with the new copper one issued as replacement.

The conclusion is it could be the head gasket passing a small amount of oil into the combustion chamber fouling the plug.
Regards
Granny.......eggs, so forth, but be sure to anneal the copper gasket - even new ones can have been stamped out of age hardened sheet.
Never too old to learn new tricks sir.
Many thanks for the heads up :beer:
Roger
ColourNcoat
Posts: 140
Joined: Thu Oct 22, 2020 8:07 pm
Location: Monmouthshire UK

Re: Carb question.

Post by ColourNcoat »

Exhausted all but changing the carb so will put a wanted add up later.
Cheers all :beer:
Roger
Mick D
Posts: 2886
Joined: Mon Mar 24, 2014 5:44 pm
Location: Aberdeenshire

Re: Carb question.

Post by Mick D »

ColourNcoat wrote:Exhausted all but changing the carb so will put a wanted add up later.
Hi

And risk getting another unknown carb? - better to bite the bullet and get a new one.

You didn't confirm if your pilot jet is new or just new to the carb

Regards Mick
ColourNcoat
Posts: 140
Joined: Thu Oct 22, 2020 8:07 pm
Location: Monmouthshire UK

Re: Carb question.

Post by ColourNcoat »

Mick D wrote:
ColourNcoat wrote:Exhausted all but changing the carb so will put a wanted add up later.
Hi

And risk getting another unknown carb? - better to bite the bullet and get a new one.

You didn't confirm if your pilot jet is new or just new to the carb

Regards Mick
Hi Mick,
I'm afraid of buy ing a new one to find out its not the carb.
All jets are original and clean to an inch of their lives ;)
I'm trying to give information as short as possible as the amount I've tried is pages long :D
The head and all components were removed today. New head gasket fitted and exactly the same :cry:
Exhaust pipe was sooty black not oily black.
It is dumping fuel in there. I turn the fuel tap off and it starts running good after a while.
Float level has been checked. :roll:
Literally running out of ideas.
Regards to all.
Roger
Mick D
Posts: 2886
Joined: Mon Mar 24, 2014 5:44 pm
Location: Aberdeenshire

Re: Carb question.

Post by Mick D »

ColourNcoat wrote:All jets are original and clean to an inch of their lives
Hi Roger

By 'original' I assume the jets came with the bike and as such you know nothing of the history of them. My suggestion the the PO has accidently over bored the pilot jet is based on the symptoms you have reported, if you haven't already fitted a brand new pilot jet or confirmed the flow rate of the one installed I suggest you make this your next move.

If you are buying a new pilot jet it would be false economy not to buy a main and needle jet too.
ColourNcoat wrote:I'm afraid of buy ing a new one to find out its not the carb.
Buying a second hand carb is very risky, buy a 'pup' and it will cost you more than a new one.

Regards Mick
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