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Carb identification

2K views 12 replies 5 participants last post by  johntioc 
#1 ·
Can anyone tell me what model these carbs are? There from a basket of parts and have no numbers on them. TIA
 

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#8 ·
In his picture I see a casting mark where the number is stamped on your example, so I am guessing it never had them.

That cold start plunger looks identical to the one on my '72 Mikunis (from a Yamaha DT2). I wonder if Amal sourced parts from them, in which case parts might be interchangeable?
 
#12 ·
By the way, those are high performance velocity stacks, and not simple bellmouth intakes. Notice the low speed air ports are NOT in the intake airstream of the stacks. It makes a difference! Your carbs will work best with a lumpy intake cam that will allow everything they can swallow to make it into the combustion chamber.
 
#13 ·
There was design collaboration between Amal and Mikuni and I think some Amal jets might fit some Mikunis.
Only the main jet Amal and Mikuni # 4/042.

There are more to problems with the cold start plungers than the rubber seal. The body wears where the plunger rests against the transfer port. To cure this they made the plunger longer. For the carburetor to work the side of the plunger MUST close the transfer port. With the new longer plunger (the old short ones are no longer available) the plunger extends up in the unworn portion of the body. This keeps the plunger from sealing off the transfer hole and you have a major air leak that is difficult to locate.

The body wears from the constant change in manifold vacuum between intake strokes. The constant pulling, and then releasing, on the plunger wears the bottom of the hole in the body where the plunger resides.
John
 
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