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Amal Premiers don't fit

Submitted by karl_nixon on Fri, 29/03/2013
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Commando

Hello All, I am (still) rebuilding my Mk2a 850 Roadster and today the job was to fit new pair of Amals. All was going well (if a bit fiddly - single carb people can feel smug at this point) but as I tightened the second carb and manifold onto the head (rh10 type) the two inner faces of the carb mounting flange and the inner part of the casting, that would be the throttle stop screw housing if it was on outer face, hit each other just before the manifold seats on the head ( BAD WORDS WERE SAID). Looking at the old carbs they have been cast with small flats in these areas (MORE BAD WORDS) It's Easter so I can't phone the makers or supplier (YES YOU GUESSED IT - MORE BAD WORDS) has anyone else had this problem with new Amals?? Have I got the wrong carbs or do I have to take a file to a pair of new carbs???? I bought them thinking they were worth the money because of the improvment over old type and that they would fit without a hassle (MY LIST OF UNPRINTABLE WORDS IS NOW VERY LONG) Thank you for reading - KARL

Submitted by peter_weait on Fri, 29/03/2013

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HI Karl These carbs are made to fit many bikes, if the rest of the carbs are right (jets, slides, needles, etc ) just file the flats as per your old ones and make sure you clean out the filings out. I have had to do this many times. I have known people not notice the problem and bent the carb. Good luck Peter Weait

Submitted by alan_clarke2 on Fri, 29/03/2013

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Previously wrote:

HI Karl These carbs are made to fit many bikes, if the rest of the carbs are right (jets, slides, needles, etc ) just file the flats as per your old ones and make sure you clean out the filings out. I have had to do this many times. I have known people not notice the problem and bent the carb. Good luck Peter Weait

Hi Karl, I had the same problem last year when I fitted new Amals toan 850 Mk2A. I did the same thing as Peter, I filed the bit off that was fouling the other carb. I asked the supplier about this and they told me that If I had ordered carbs for the Mk3 Commando they come with the bit machined off.

Cheers Alan, Shenstone branch sec.

Submitted by richard_payne on Fri, 29/03/2013

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The original build code for the Commando carbs included the fact that they machined back the unused tickover screw bosses to allow for the close fitting parallel inlet tracts. 'Standard' Amals or carbs built up from standard spare parts have never included this and it has always been necessary to gently file the inner boss on each carb. It's simply a consequence of the use of a universal casting. It has nothing to do with the 'Premier' aspect. It is probably thirty years since I first had to do this.

Those hours spent filing billet into cubes at school suddenly become worthwhile.

Submitted by anthony_curzon on Sat, 30/03/2013

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There was a service release that was issued by Norton's in the late 1960's or 1970 that explained about this carb problem. It was on a very large poster, and explained that if the carbs do not fit correctlyto file them for clearence. I managed to find this service poster a while back, and it has a lot about the other service problems that are Commando related.

Submitted by mick_prentice on Wed, 10/04/2013

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Ordered my carbs for a 72 Interstate direct from Amal, fitted first time no problem at all. Have to say they have been some of the best money I've spent on the bike in 30 years, also ordered the thinner air filter element and SS mesh from RGM, makes playing with the carbs at hell of a lot easier, again good money well spent.

 


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