Amal Premier carbs

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My carbs are shot and I’m going to buy premiers for my ‘73 Norton Commando.
I’m running Donald Pender’s throttle assembly without choke assembly.
My question is are parts from the old carbs interchangeable with the premiers? Like the mixing chamber top, float bowl and jets?
 

Fast Eddie

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My carbs are shot and I’m going to buy premiers for my ‘73 Norton Commando.
I’m running Donald Pender’s throttle assembly without choke assembly.
My question is are parts from the old carbs interchangeable with the premiers? Like the mixing chamber top, float bowl and jets?
Yes.
The pilot jet is very different and much improved on the Premier though so no interchangeability there.
 

cliffa

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When you get them I would strongly advise removing the air screw and pilot jet and shake them or blow them through as many folks (including me) have found machine swarf in the centre mixing chamber which upsets the idle.
 

lazyeye6

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Order with the #25 pilot jet otherwise they will ship with a smaller size which will make you very unhappy.
 

marshg246

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Order with the #25 pilot jet otherwise they will ship with a smaller size which will make you very unhappy.
Premier carbs for 850s come with #19 and 750s come with #17 there is no #25 - that's the old days when there were pilot jets in the MK1 carbs and that's today's the MKII carbs - not the Premier MK1 carbs.
 

Tornado

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OP:
Why do you need to swap parts of MKI to your new Premiers?
They come fully assembled.
 
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The old 25 pilot bush has a 17 thou hole, same as the Premier #17 pilot. Somewhere in the new pilot circuit the fuel routing has an effect and on some engine the Premier #17 acts lean so a Premier #19 jet works better.
 

Fast Eddie

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My 650 Bonnie needed #19s and so do many Tridents. So hole size notwithstanding, there’s definitely something making them run leaner it seems.
 
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I would strongly suggest you consider purchasing your Premier carbs from Greg Marsh (see his response above). He had the best price of any supplier (see possible discount for Forum members), quick shipping, plus if you ask him like I did, to check carbs for any factory left over junk inside, he will take them apart and make sure everything is really plug and play. I really appreciated that service since I am not a mechanic and did not want to mess with my new carbs. His price might be competitive even in your location. Plus a great guy to deal with and takes the time to answer questions, no attitude. Check him out. I was super happy with the product and with Greg. Good luck, you will like them.
 

marshg246

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My 650 Bonnie needed #19s and so do many Tridents. So hole size notwithstanding, there’s definitely something making them run leaner it seems.
The T120R I just finished is running fine with #17 but my air screws are out 1-1/8 turns and are a little touchy so #19 might have been better. It has a new exhaust system that appears as stock, but the mufflers are basically open and it has standard Triumph air filters. The last T120R I built had original mufflers and with #17 the air screws were out slightly over 1-1/4 turns and not touchy. So, IMHO, there's more to it. All bikes with standard carbs work (for better or worse) with the fixed jet.

I have the #19 jets in stock, but they are expensive so I only install them when I really have to.
 

marshg246

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My 650 Bonnie needed #19s and so do many Tridents. So hole size notwithstanding, there’s definitely something making them run leaner it seems.
I learn something every day! I responded to this that the 70 Bonnie I had just finished worked fine with #17. That was true, but...

When setup to idle nicely when cold and to take a throttle blip without stumbling, the air screws were out 1-1/8 turns - not terrible. However, when warmed up, the idle was too fast. Adjusted the idle for warmed up and put the bike away. Yesterday it didn't want to idle when cold so I turned the idle up and went for a ride - again when warm, too fast - again reset and put the bike away.

Today I put in #19 pilot jets in and turned the air screws out 1-1/2 turns. Bike fired and idled at about 600 RPM. Got on and went for a ride. Once warmed up, the idle was around 1000 RPM. Touched up the air screws - now both are about 1-3/8" turns out and it's running great.

Just a theory - I think it's not an air/fuel mixture issue but an amount of mixed air and fuel being fed to the cylinders. Why? I'm now allowing more air and more fuel to flow and it is running better, especially when cold.
 

worntorn

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I see that Amal now offers the Premieres in Aluminium rather than Mazak.
I'm not sure that this is an actual improvement as most motorcycle and automotive carbs are made in some form of Mazak because it works so well for intricate castings.

Glen
 

marshg246

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I see that Amal now offers the Premieres in Aluminium rather than Mazak.
I'm not sure that this is an actual improvement as most motorcycle and automotive carbs are made in some form of Mazak because it works so well for intricate castings.

Glen
They have had 600-series in AL for a long time. The dealer price list and web site do not list 900-series in AL.

600-series: http://amalcarb.co.uk/mk-i-concentric-series/600-series/aluminium-premier-carbs.html

This is the second time today I've heard this - where did you hear it?

They are still out of stock on most 900-series Premier carbs and have been on and off for over three years. I have many backorders waiting for them.
 

marshg246

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Very interesting - I've written Amal to see what the #$)*#$)*%)#$ is going on.
 

marshg246

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Update..

Amal is working on producing 900-series carbs in AL. They have not been officially released and therefore do not show on their web site or in the dealer price list. Coventry Spares is the only place that got any and that was due to the age of their backorders. The point of the AL is reduced weight. According to Amal for the 600-series "The aluminium carburettor offers a weight reduction of around ¾ lb over the traditional zinc alloy type."

Amal continues to have trouble producing the 900-seies carbs (standard and premier). For instance, for all my outstanding backorders, they can only supply one today that is for Norton and three that are for Triumph.
 

worntorn

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Wow, a pound and a half on two carbs, that's a lot if you are building a light bike.
I'm struggling to find ways to knock off a couple of ounces here and there for the lightweight Commando project.
I have carbs for it but might need new ones:)

Glen
 

cliffa

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I'm sure that Surrey Cycles have done aluminium for years.


whether they have stock is another question though.
 
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