Misc: Ignition Need Advice, can't keep an idle (intermittently) approaching or at a stop with New Amal 276's

hadronuk

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An observation about the earlier suggestions to move the 276 float chamber forwards/backwards to counteract fuel surge.
When measured carefully, I found the mounting faces of my standard manifolds are not accurately vertical. This results in the bore of the rear carburettor sloping down a fair bit towards the engine, whereas the front carburettor bore slope slightly upward.
Consequently moving the float chamber alters the fuel height at the main jet quite appreciably, especially on the rear carburettor. Its also more pronounced if you have the long arm float chambers. I use the short arm ones and have fitted a sort of capstan to the mixture screws so they can be adjusted from the side when they are behind the float chambers.
 

kerry

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May be worth mentioning . About 4-5 years ago a batch of shadow 276 carbs were made wrong, from memory I think I had to buy a .80mm drill and drill an internal hole, a phone call to Amal may help as they told me to do that at the time as my bike would not run off chokes !
 

Chris.R

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My Comet with a rebuilt remote float 29 slide 3.5, needle in slot 3 middle pilot at 1-1/4 and slide set at 1/16 will not idle satisfactorily in fact a couple of days ago she did a ten mile run with some spitting back, but ran. Yesterday chocked on anything other than full choke ease off and she stalled, stalling twice on a run round the block so unable to get her up to working temp to try what I had been advised to do test for air leaks with WD40 around carb mounts. What next?
 

Bill Thomas

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I would start with the checking the flow from the tank,
Has the tank been sealed with stuff, Sometime bits block it off.
 

vibrac

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Double cxhack everything especially the inlet tract sealing if all else fails I would go Mikuni, the original 276 were fine I worry about the following designed Amals and later remakes
Having said that a good solution is a Mikuni on the shelf that seems to have sorted my Monoblock out I swear it knows what will happen if it goes wrong!
 

delboy

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My Comet with a rebuilt remote float 29 slide 3.5, needle in slot 3 middle pilot at 1-1/4 and slide set at 1/16 will not idle satisfactorily in fact a couple of days ago she did a ten mile run with some spitting back, but ran. Yesterday chocked on anything other than full choke ease off and she stalled, stalling twice on a run round the block so unable to get her up to working temp to try what I had been advised to do test for air leaks with WD40 around carb mounts. What next?
Sounds like classic case of cr*p in the pilot jet if it ran before okay.
Cheers,
Delboy.
 

hadronuk

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Might I also suggest that as you try different carb settings, you frequently replace the spark plug?
I have found that after only a short period of a rich tickover, the plug is sooted enough to cause a misfire even though it only looks slightly mucky.
Modern plugs don't seem to be burnt clean by a full throttle blast, as used to be normal practice. Replacement is the only option.
 
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