Amal 389 Dilemma

Discussion in 'Bonneville' started by Stephen Robinson, Aug 28, 2021.

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  1. Stephen Robinson

    Stephen Robinson New Member

    May 29, 2021
    7
    3
    Derby
    Hi Gents .
    mate called me and said he had tried to fit the air filters on his carbs, he told me the threaded holes are too big for the carbs, so i popped round to take a look, sure enough they are, i looked on the tops of the flanges to make sure the carbs are 389,s but they are blank, under the flange it has K33 stamped.??? ive checked all over the carbs and cant find any identification marks, He then told me that in its previous life with the old owner some one swapped the carbs for new ones, hence why he had the filters, the carbs have small screw on bells with mesh. Could the cabs be snides.?? none of the flanges have been filed or sanded as you can see the casting marks. Any one come across this before.
     
  2. Stephen Robinson

    Stephen Robinson New Member

    May 29, 2021
    7
    3
    Derby
    here is a pic of the under side of the flange

    IMG_20210828_181810.jpg
     
  3. Iceman

    Iceman Crème de la Crème

    Apr 19, 2020
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    what model and year is the machine
     
  4. Stephen Robinson

    Stephen Robinson New Member

    May 29, 2021
    7
    3
    Derby
    1964.
     
  5. Iceman

    Iceman Crème de la Crème

    Apr 19, 2020
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    #5 Iceman, Aug 29, 2021
    Last edited: Aug 29, 2021
    Hi Stephen as you say it should have Amal 389/203 carbs with the internal bore 11/8th - main jet 376/100-260 - pilot jet 376/076-20 - needle jet376/072-106 and needle position 3 - throttle valve 389/0603, it looks as though it could be 376 carbs, although I can't be sure, the best bet would be to measure the carb internal bore to narrow it down further. The trouble is unless your friend bought it new then previous owners change all sorts of parts, often from other makes. A 1956 T100 uses the same carb as a BSA 500 A7, it just utilises different internals. I have looked in my archives for Amal and am unable to see anything with the prefix K33, I will have a look through some other reference information later next week and update you on anything I find.
     
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  6. Stephen Robinson

    Stephen Robinson New Member

    May 29, 2021
    7
    3
    Derby
    This gets even more bazar, Yesterday he turned up with what he says are the original carbs, a handed pair of Amal930,s in filthy condition, he managed to trace the man that swapped the cabs, via the previous owner info, Paid the chap a visit and asked if he had the original carbs he took off the bike some years ago, and hey presto. however, from all i have read it seems as they are not correct and that 389,s should be fitted to that year 1964?? , I have stripped and cleaned the carbs in a sonic cleaner and am awaiting new gasket sets for them. The air filters that came with the bike do fit, So is it possible that the 930,s are correct.
     
  7. Iceman

    Iceman Crème de la Crème

    Apr 19, 2020
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    Hi Stephen, if the machine is a 1964 then the correct carbs should be the 389/203 with the jets etc as I mentioned, the 930s were fitted to a range of models such as the TR6 - TR6R - TR6C - TR6 Police and fitted between 1968 and 1973, they were also fitted to the T120 - T120R - T120V from 1967 to 1973, they were also fitted to the T140V - T140D - T140E from 1973 to 1978 - Les Harris also fitted them to his Bonneville's from 1985 to 1987, all had the same internal bore of 30mm but obviously different jets etc. The 930s would not have been fitted as standard when new on the 1964 they came later on. It's a good job your mate has a good knowledgeable friend like yourself otherwise it sounds like he may struggle a bit. I will let you know re the K33 carbs as soon as I can. Let the forum know how you get on.
     
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  8. Iceman

    Iceman Crème de la Crème

    Apr 19, 2020
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    Hi Stephen, sorry it has taken so long to get to the bottom of your carb issue, however here is some information that may shed light on your carbs. The carburettors on your bike were made by Grosvenor Works, the company that owned Amal before Burlen. They didn’t stamp the carburettors with specification numbers as the carbs were sold into the trade and jetted by individual dealers. It is safe to say the supplying dealer stamped the carbs hence the strange numbers. Amal can supply the correct carbs if you wish to go down that route, although a pair will not be cheap. I hope this helps you.
     
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