Carb question.

Information relating to the Matchless G2 or AJS Model 14 250cc Lightweight
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ajscomboman
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Re: Carb question.

Post by ajscomboman »

I've got to agree with Mick, buying a used carb without being able to dismantle it first will be throwing money away. If you buy new and it's not the cause of the issue you'll still get a better return on it if you sell it on.
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dave16mct
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Re: Carb question.

Post by dave16mct »

Just a thought, you say you've stripped the carb. When you did that did you take out the jet block to check the paper washer? I had one carb that had half of the washer missing. It ran very rich until the petrol was turned off, then perfect for a few seconds until it cut out. Worth a look?
Dave.
ColourNcoat
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Re: Carb question.

Post by ColourNcoat »

Mick D wrote:
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
Hi Mick,

The jets are all original and yes you are right in what you say.... No-one know whats been done over the years.
Regards
Roger
ColourNcoat
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Re: Carb question.

Post by ColourNcoat »

ajscomboman wrote:I've got to agree with Mick, buying a used carb without being able to dismantle it first will be throwing money away. If you buy new and it's not the cause of the issue you'll still get a better return on it if you sell it on.
Everyone is right but then if I purchased a kit would there be anything else wrong with the carb once this is done.
So kind for all giving advice.
Regards
Roger
ColourNcoat
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Re: Carb question.

Post by ColourNcoat »

dave16mct wrote:Just a thought, you say you've stripped the carb. When you did that did you take out the jet block to check the paper washer? I had one carb that had half of the washer missing. It ran very rich until the petrol was turned off, then perfect for a few seconds until it cut out. Worth a look?
Dave.
Hi Dave,
I did remove the jet block and there was a paper washer on it in one piece but this could be something overlooked as a problem area :beer:

Regards
Roger
Mick D
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Re: Carb question.

Post by Mick D »

ColourNcoat wrote:if I purchased a kit would there be anything else wrong with the carb once this is done.
Hi

If it's an old carb the slide and bore will be worn to some degree, (expensive to resolve), which will cause poor slow running.

Carbs aren't black magic, you just have to approach rectification in a structured manner - do the most obvious basics first. You seem to be reluctant to do this preferring a 'shotgun' approach.

All of your symptoms point to an over rich idle mixture - based on what you report, replace the jets and go from there ;)

Regards Mick
Stan Palmer
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Re: Carb question.

Post by Stan Palmer »

On all the bikes I have rebuilt I tried to refurbish the carb. In each case except one I ended up buying a new one. The exception was the SU carb on the Thunderbird, despite zero confidence it started and ran perfectly! The symptoms were variously flooding, bad starting and rough tick over. It seems easier to get the high speed sorted than the lower.
I don't learn though, just bought another eBay item for the mountain cub. No doubt that will end in my growing box of bits.
Stan
SPRIDDLER
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Re: Carb question.

Post by SPRIDDLER »

ColourNcoat wrote:
Everyone is right but then if I purchased a kit would there be anything else wrong with the carb once this is done.
Possibly. There's difficulty with diagnosing at arms-length...........

Because as we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know.

and we all know who said that ;) .

WRT buying a second hand replacement carb I also know that I don't know anyone who felt it necessary to replace a known good carburettor.
'There is a tide in the affairs of men
Which taken at the flood............'
SPRIDDLER
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Re: Carb question.

Post by SPRIDDLER »

A separate post as I've had another thought.
I haven't trawled back over all 6 pages but are you sure that the choke is going completely off? Choke Off is with a tight wire. If you open the throttle wide with the choke Off a finger in the inlet should not feel any obstruction other than the needle in the slide. This occurred to me because another member's recent post mentions that the PO had fitted the sliding choke piece in the slide upside down and the choke never went completely Off.

Before getting a new carb I'd get the kit from the club spares, Amal or Burlen (there are fake ones on eBay). You never know but the PO may have fitted a two-stroke needle.
Crumbs - just looked at the price of a kit. It's more than 50 quid. Hmm :?
'There is a tide in the affairs of men
Which taken at the flood............'
ColourNcoat
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Re: Carb question.

Post by ColourNcoat »

Everyone has a very valid point and is changing my thoughts towards getting a new one. It does stick in my gut that I have to spend yet more money on this little treasure to finally get it done.
I know you can't put a price on everything but in this case I have to draw a line somewhere, yet I have to get it finished.
How many people have spent more than something is worth without having sentimental attachments?
I am grateful so will try and find best price now. :beer:

God I hate being beaten :headbang: :D :D
Regards
Roger
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