How To Select An Amal Concentric Carburetor

How To Select An Amal Concentric Carburetor

Choosing a new carburetor for your vintage British motorcycle can be challenging and confusing as parts over the years often get changed

Although all Amal Concentric (MK1) carbs look the same, internally they are not 

Understanding the challenges one may face, I was motivated to compile a simple yet effective chart below that will aide you when purchasing a new Amal Concentric carburetor from Classic British Spares or perhaps selecting an original carburetor for your application 

We understand that this topic could be discussed in great lengths, however we will keep it short and to the point which will help “most” folks make the proper choice when seeking a new Amal Concentric carburetor 

Before we go over our chart, we hope that you check your parts book, workshop manual and your manifold to help you identify what carb you may need

Workshop manuals and parts books

Workshop Manuals & Parts Books

Did you know that a factory workshop manual and a factory parts book will list the proper carburetor that was fitted to a specific machine?

When in doubt, grab a workshop manual or a parts book for your year, make and model and find the carb size that was originally fitted to your machine

Click here for a free parts book and click here for a free workshop manual


Measuring Inlet Port BSA C15

Should you have the proper manifold on your motorcycle, it is important to measure the inside diameter to obtain a reading either in metric (for Amal Concentric carbs) or imperial / inch (for Amal Monobloc carbs)

Using the measurement from your manifold, it will aide you in finding the proper carb - please keep in mind that some manifolds taper and some manifolds may have a different bore size than the carb that would normally be fitted

Those that do not have an external or "bolt on" manifold, you can measure the opening of the inlet port (shown above)

Cylinder head casting numbers

Triumph Cylinder Head Casting Number

Often times hidden and hard to find, a casting number can provide you with much information in regards to the identity of the given head and also the port size

Always check your casting number first to find the original origins of your cylinder

Your specific application


Dual Carb Triumph Race Engine

Having good judgment also helps when making a carb selection

Knowing your engine specs and overall condition (stock, modified, cams, pistons, etc) may give you a good idea as to what can be fitted to your engine 


Amal Concentric carbs fitment list

Amal Concentric carbs where fitted to some models in 1967 but fitted to all models starting in 1968-1978 (early)

Here are some things to know when considering an original, new or Amal Premier Concentric carb..


  • R = Right Hand
  • L = Left Hand
  • 900 series / 30MM = 930
  • Mounting Spacing = 2" (same as Monobloc)

Below is a quick chart of Amal Concentric carbs and applications

Click here to purchase or view our entire inventory of Amal Concentric carburetors 




 Application (Make / Model / Year) Carb Type Bore
T120 / T140 1968-1978
R930 & L930 Set (Concentric)  30MM
TR6 / TR7 1968-1983
R930 (Concentric) 30MM
T150 / T160 1968-1976 627 Carb Set (Concentric) 27MM
TR25W / T25 1968-1972 R928 (Concentric) 28MM
T100R 1968-1974 R626 & L626A Set (Concenteric) 26MM
T100C / TR5T R626 (Concentric) 26MM



 Application (Make / Model / Year) Carb Type Bore
A65L / A65FS 1968-1972 R930 & L930 Set(Concentric) 30MM
A65 Spitfire 1967-1968  R932 & L932 Set (Concentric) 32MM
C25 / B25 1967-1970 R928 (Concentric) 28MM
A50 1968-1970 R626 (Concentric) 26MM
A75 / Rocket III 627 Carb Set (Concentric) 27MM
A65T 1968-1970 R928 (Concentric) 28MM
B44VS / B44SS 1968-1970 R930 (Concentric) 30MM
B50 1971-1973 R930 (Concentric) 30MM


Application (Make / Model / Year) Carb Type Bore
Commando 750 R932 & L932 Set (Concentric)  32MM
Commando 850 R932 & L932 Set (Concentric)  32MM


Click here for more information on the new "Amal Premier carburetors" 

Amal Monobloc carbs fitment list

Many folks like to install Amal Concentric carbs on early Triumph and BSA models as an “upgrade”

Below is a chart suited for early Triumph & BSA models that would like to upgrade to a Concentric carb

*When upgrading from an Amal Monobloc carb, keep in mind that your existing throttle cables will need to be changed or modified to work with a Concentric carburetor

Click here to purchase or view our entire inventory of Amal Monobloc carburetors 


Triumph Monobloc Replacement Carbs


Application (Make / Model / Year) Carb Type Bore
T120 1959-1965 R930 & L930 Set (Concentric) 30MM
TR6 / 6T To 1965 R930 (Concentric) 30MM
T110 R930 (Concentric) 30MM
T90 / T100 1963-1967 R626 (Concentric) 36MM
T100R 1967 R626 & L626A Set (Concentric) 26MM

BSA Monobloc Replacement Carbs


Application (Make / Model / Year) Carb Type Bore
A65T / A65H 1962-1967 R928 (Concentric) 28MM
A50 1962-1967 R626 (Concentric) 26MMM
A65L / A65H 1964-1967 R930 & L930 Set(Concentric) 30MM
B44VS 1966-1967 R930 (Concentric) 30MM
B40 1958-1965 R928 (Concentric) 28MM
A10 (Alloy Head) R930 (Concentric) 30MM
A7 (Alloy Head) R928 (Concentric) 28MM


We understand when replacing your carb or choosing a new carb it can be difficult and challenging, if you appear to be having trouble we are here to help 

Click here to send is us an email and we will inform you on which Amal Concentric carb or Monobloc carburetor you need 
Thanks for reading
Ride safe!


  • Jeff Marsh

    I would like to buy an Amal Premier carb for my 1958 BSA A10 Super Rocket
    I don’t know the correct slide and jets required.. can you help?


    .. Jeff

  • Arthur

    1961 triumph t120 how much for a pair of concentrics with correct jetting,I have a pair of 928,s on now but it won’t runk

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  • otrumonova

    Жетоны на заказ. Купить, продать коллекцию жетонов. коллекцию монет.

  • Classic British Spares

    @DAG – we stock different slides – 27MM

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