Premier Carbs on an 850

Hi guys a friend is considering fitting Premiers to a Mk2 850 and has asked for my/ your help. Do Premiers sill have the cut away spray tube and 4 ring needles? I cannot see either on Amal/ Berlin's web site.

Only if you buy the ones specifically for 850, the generic Premiers will come with the std spray tube and needle.

If you go to the Amal site and go in via the model search selecting 850 MK2 you get to


They should also have the 19 pilot as std instead of the 17 fitted when the premiers were introduced.

Short answer is yes, if you get the right pack. Greg Marsh is who you want to ask. He set me up with the correct Amal Premier pack for my MK2 850.

PACK 136

Bonzo said:

PACK 136

Andover Norton Parts Drawings - Genuine Andover Norton Factory Parts - Commando Parts

Andover Norton Parts are the only Norton spare parts in the market manufactured to original drawings, within the factory-approved tolerances, from the correct materials, and with the correct finish.

andover-norton.co.uk

Click to expand...

That's an interesting variation of main jet sizes for the 850s. Is that because of different air filters a d silencer combinations? If so, if you're running non-stock items (e.g. not using black cap silencers) that may affect which pack is the right one.

Mart UK said:

That's an interesting variation of main jet sizes for the 850s. Is that because of different air filters a d silencer combinations?

Click to expand...

Yes, 850 Mk1 and Mk2 carb specs. are different to Mk1A, Mk2A and Mk3, however, the information for "850 Mk2a PACK138" (3.0 slide, 200 main jet) in the AN list is wrong! "932/35 & 932/36" are later Mk2, not "Mk2a".
The next line of the list has "850 Mk2a/Mk3, PACK113, 932/33 & 34" which is correct!

" 06.7334
CARB PAIR - AMAL PREMIER 32MM (850 MK2A/Mk3) 220 JET PACK 113"

L.A.B. said:

Yes, 850 Mk1 and Mk2 carb specs. are different to Mk1A, Mk2A and Mk3, however, the information for "850 Mk2a PACK138" (3.0 slide, 200 main jet) in the AN list is wrong! "932/35 & 932/36" are later Mk2, not "Mk2a".
The next line of the list has "850 Mk2a/Mk3, PACK113, 932/33 & 34" which is correct!

Motorcycle parts and spares for Norton motorbikes - Genuine Andover Norton Spare Parts - Andover Norton Motorcycles Parts - Original Andover Norton Parts

Motorcycle parts and spares for Andover Norton motorbikes: Andover Norton manufactures and supplies all Genuine Factory Spare Parts for Norton motorcycles built before 2002.

andover-norton.co.uk

" 06.7334
CARB PAIR - AMAL PREMIER 32MM (850 MK2A/Mk3) 220 JET PACK 113"

Click to expand...

Thanks LAB. So, that's the correct pack if you still have black caps and the original airbox. I have neither, which I'd expect is true for a lot of mk3s. Would that suggest starting with the mk1 pack?

That said, I toy with the idea of going to 2 carbs from my single 34 series 2 Amal, just to see if I'm missing something and because I don't [currently!] have any excuses to work on the bike. But, I'm happy with how it currently runs, so....

Mart UK said:

So, that's the correct pack if you still have black caps and the original airbox. I have neither, which I'd expect is true for a lot of mk3s. Would that suggest starting with the mk1 pack?

Click to expand...

Yes, although the primary difference between 850 Mk1/Mk2 and Mk1A/Mk2A/Mk3 is main jet size so a carb pack with 260 main jets would perhaps be a better starting point where changes have been made to the airbox and exhaust system.
All standard 850 carbs should have the 928/107 stepped spray tube and 928/104 needle.

However, according to both the Mk2/2A parts supplement and Mk3 parts book, these carbs supposedly had the 622/055 float bowls with the 0.125" float needle seating orifice instead of the usual 0.100". I don't know if the currently supplied carbs or carb packs actually have the 622/055 float bowls or not!

The Mk2/2A/Mk3 carbs would have had the double 180-degree banjos for the later fuel line and not the previous single banjos used with the 'H' fuel line, however, the banjos were originally part of the fuel line assembly, although AN now sells the individual fuel line components.

Thanks for that, our problem in New Zealand [being so far away- freight costs] one of the Andover Distributors here sent my friend a Generic set of premiers I think the number was 300/301, no cutaway spray tube, #3 slide and no chamfer on the bodies, we did not open them up to see what needle etc was there, I suggested he send them back.

You will find various lists on the Internet of which carbs go with which "year" or "model" of Commando. As far as I can tell, besides mistakes, Amal uses records of what was (pre-)ordered and when, and AN uses parts manuals. For instance, Amal lists this: 1974 and later Commando Roadster MKIII 850cc R932/42 L932/43 but there is no evidence that Norton ever used those carbs.

Since there is no such thing as a "model year" for Norton, and "Marks" were changed whenever, and there wasn't a parts manual for each model/mark, there is no authority on which carbs you need. I've tried very hard to make my listing the best it can be with help from some here and the available documentation. See the bottom of this page: https://www.gregmarsh.com/MC/Norton/CommandoID.aspx

The good news is that there is actually little variation in the carbs. The 850 carbs are all 932s and only really vary in main jet size - they all have 3-1/2 slides, 106 needle jets, Norton-specific needles and the Norton-specific spray tube. The 750 carbs are either 930s or 932s but all have 3 slides, 106 needle jets, standard needles, and standard spray tubes. Amal specifies #19 pilot jets for the 850 sets and #17 for the 750 sets, but I order them with #19.

The air cleaner, mufflers, and gasoline determine the main jet but unless you use more than 3/4 throttle a lot, the size is not critical. Based on old Triumph documentation, I recommend one size bigger for E10 gasoline.

Amal carbs have a number like R932 (right side 32 mm) and 2 or three more numbers such as 42. The second number defines the carbs variables. When that second number is 300 or 301, it is a generic carb that the dealer is supposed to make right for your need. They are never right for an 850 since they have the standard needle and spray tube. There are also stories of all sorts of aftermarket parts being put into them.

If you are trying to win concours shows, you need the right second numbers if the judge is knowledgeable but otherwise, the second numbers don't matter.

As always, you can call to discuss. 703-200-4025.

Thanks Greg, I have owned raced and worked on Commando's for close to 50 years and am quite familiar with normal Concentics and their differences but until now had no experience with Premiers. My friend asked me to view the Premiers that he had ordered from the Dealer specifically for a 1974 850 Commando which is by numbers a Mk2, as stated the carbs were suppled with standard spray tubes, #3 slides and did not have the chamfers opposite the idle adjusting tubes. I was unsure if Premiers had the cut away spray tubes and 4 ring needles and appreciate you confirming that they should.

All Concentric Mk1s whether standard or Premier need the flats on the unused throttle stop bosses (and inner mounting flanges to a lesser extent) or they won't fit side by side on the inlet manifolds without clashing, however, that can easily be rectified although it should've been done by the supplier if generic 300/301 carbs.

The 928/107 stepped spray tubes and 928/104 needles were fitted to cure what was a non-existent problem on 850 models in order to pass a US acceleration test requirement when mutes were fitted to the exhausts and under test conditions that wouldn't be encountered during normal riding.

My Mk3 has generic 932/300 & 932/301 carbs with standard flat-topped spray tubes, 622/124 4-stroke needles, and 3.0 slides. It runs absolutely fine in that configuration and I doubt it would run any better with the stepped spray tubes, etc.