es2 1953 amal 276 FT/IDJ

If you are tickling it to start and it will run for a few mins ,I would suspect poor fuel supply or low fuel level. 

Thats just enough fuel to do what it does.  But the normal supply is not being drawn in.  Its most likely that the small passages in the carb are  partially blocked .  I would do a total strip including removal of jet block which will expose the tiny fuel ways. It could also be that the fuel level is too low. Float needle wrong or incorrect parts that the float chamber mounts   on.

Hi Mike,

   As Robert says this is probably fuel starvation. Remove the petrol pipes and check the fuel is running freely from each tap and check the breather hole in the filler cap is not blocked. It is possible, depending on what type of petrol pipes you have, to get an air lock in the pipes. Before you start kicking, turn on both taps and when the bike is running O.K. turn off the near side reserve tap and see how the bike runs then. Make sure you have the correct float and it's clip is engaged in the needle correctly. On the float chamber make sure there is no blockage in the bottom arm feed hole, you might need to remove the small blanking bolt. Check you have the correct slide needle as the 289 is longer and that the clip is a good fit and start with it in the middle position to see if it runs O.K.

Later carbs like the monoblock have bigger internal passages and the very fine pilot jets are easily removable ,so can often be cleared  with a blow thro.  The pre monoblock carbs are very different with no removable pilot  and very fine long passages  that are not readily accessible unless you knock out the block   Take care and  renew the paper gasket  betwixt  block and body which can block fuel if not sized properly. Read up to avoid damaging the parts. Find an enlarged detail of the pilot and bypass system and study it , if you are good with IT   please post a blown up detail and macro photos  to help those that follow.