Beast and the carb

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
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spookefoote1956
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Re: Beast and the carb

Post by spookefoote1956 »

Yes you are!
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All my bikes are original........ to me!
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StephenG80
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Re: Beast and the carb

Post by StephenG80 »

Hi Spookefoote1956 - re your Ni RH top A/R cable entry - when you set the timing did you have the timing fully advanced? ie the lever pulled fully back? :ugeek:

Stephen
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spookefoote1956
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Re: Beast and the carb

Post by spookefoote1956 »

Certainly did. I think it's pretty much timed right. The plug I was using may well have been too cold (B8) so I've ordered some hotter ones which should arrive by tomorrow.
Hail Joe Lucas ............ Prince of Darkness!
All my bikes are original........ to me!
"Creativity is your intelligence having fun" Albert Einstein
StephenG80
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Re: Beast and the carb

Post by StephenG80 »

Oh well at least that is taken out of the equation - look forward to seeing a wee vid of you riding this bike - you've certainly put the time in! :beer:
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spookefoote1956
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Re: Beast and the carb

Post by spookefoote1956 »

So today this is where I'm at. Put the B6 plug in. She fires bang, bang, bang, bang, bang, stop. However this is happening consistently so I'm happy with the timing, no kick back. I checked the float level with some tubing and that appears to be OK, although I have the shim kit ready. Altered the plug gap and that seemed OK but I still can't get her to keep firing. The air crew is one and three quarters out as is the tick over screw.

Should I try the shims and how do I go about it?
Hail Joe Lucas ............ Prince of Darkness!
All my bikes are original........ to me!
"Creativity is your intelligence having fun" Albert Einstein
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dave16mct
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Re: Beast and the carb

Post by dave16mct »

Sounds like you need choke. I presume you're using the tickler to flood the carb?
Dave.
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spookefoote1956
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Re: Beast and the carb

Post by spookefoote1956 »

Flooded with the tickler and the choke has been removed.
Hail Joe Lucas ............ Prince of Darkness!
All my bikes are original........ to me!
"Creativity is your intelligence having fun" Albert Einstein
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clanger9
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Re: Beast and the carb

Post by clanger9 »

Good, now you are getting somewhere! :)

Don't mess with the shim kit, there is only one correct float level for an Amal and it sounds like yours is right.
Timing seems OK from what you describe. Now onto the fuel mixture...

When it fires, is it 8-stroking (firing every other compression)? Does it produce black smoke? Does it respond at all to the throttle, or just pop-pop-pop-stop?
1989 Moto Morini Dart 350
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SPRIDDLER
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Re: Beast and the carb

Post by SPRIDDLER »

spookefoote1956 wrote: The air crew is one and three quarters out as is the tick over screw.
I'm not being pedantic, but in order to avoid chasing hares, by 'air crew' do you mean the horizontal short Pilot screw? And by 'tick over screw' I assume you mean the near vertical and longer slow running screw.

The Pilot screw setting is about right. However, the slow running screw has no effect on setting the mixture (as in tuning the carb); it merely lifts the carb slide as if you were opening the throttle a bit by using the twistgrip. The number of turns in or out to achieve your preferred tickover speed is entirely a matter of personal choice.
Should I try the shims and how do I go about it?
What shims? If you mean under the carb inlet banjo this will raise the fuel level in the float chamber which you have already checked and found to be o.k.

It sounds as though your engine is only running briefly on the 'tickled' fuel and stops when this runs out. I think you have a brand new carb (why is there no choke assembly?), even so it could be a blockage in the Pilot jet or the drillings in the carb body since at nil to around a quarter throttle open it's *only* the Pilot jet which is feeding fuel to th'engine.
Last edited by SPRIDDLER on Thu Jul 27, 2017 6:17 pm, edited 1 time in total.
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ajscomboman
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Re: Beast and the carb

Post by ajscomboman »

If you run without a choke slide the hole in the slide to accommodate it should be blocked off with copper plate or similar. Without a slide in place more air is drawn in through this hole weakening the mixture. This was a very common modification carried out on the CS scramblers which didn't need a choke.
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