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premier carbs #569229
10/26/14 11:36 pm
10/26/14 11:36 pm
Joined: Sep 2009
Posts: 632
SEATTLE WA
S
SEATTLE GS Offline OP
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SEATTLE WA
do these carbs come jetted for Norton with the Norton only needle and spray tube?

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Re: premier carbs [Re: SEATTLE GS] #569235
10/27/14 1:30 am
10/27/14 1:30 am
Joined: Feb 2014
Posts: 1,077
Lancaster, California
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Originally Posted By: SEATTLE GS
do these carbs come jetted for Norton with the Norton only needle and spray tube?



A standard AMAL Premier 930 Carb will not. You must specify when ordering what application you will be using the carbs on. Norton 750 930/30A & 930/31A. Norton 850 932/35A & 932/36A

Re: premier carbs [Re: SEATTLE GS] #569256
10/27/14 7:26 am
10/27/14 7:26 am
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Scotland
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There should be 2 850 specs, pre black plastic airbox eg MK1 and MK2 and the black airbox type for MK2A and MK3. The stepped spray tube was in the Black plastic airbox with a smaller main jet to match the black cap silencers, by fitting reverse cone silencers you need the larger main jets.

Re: premier carbs [Re: kommando] #569266
10/27/14 10:11 am
10/27/14 10:11 am
Joined: Mar 2006
Posts: 3,657
Norfolk, UK
L.A.B. Online content
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Originally Posted By: kommando
There should be 2 850 specs, pre black plastic airbox eg MK1 and MK2 and the black airbox type for MK2A and MK3. The stepped spray tube was in the Black plastic airbox with a smaller main jet to match the black cap silencers, by fitting reverse cone silencers you need the larger main jets.


According to the available information including the AMAL (Burlen) spec. list, all 850 932 carbs (5 variants) had the 928/107 stepped spray tubes and matching 928/104 4-ID ring needles.
An early 850 press release printed in the April 1973 copy of Motorcycle Sport also mentions that the 'new' model (which can only refer to 850 Mk1 at that time) has: "cutaway spray tubes".
If any 850 carbs originally had the standard 622/074 flat-topped spray tubes and 622/124 2-ID ring needles, then neither of those parts appear in either the 850 Mk1 parts list or Mk2/Mk2A parts supplement.

Re: premier carbs [Re: SEATTLE GS] #569288
10/27/14 1:23 pm
10/27/14 1:23 pm
Joined: Dec 2004
Posts: 9,332
Scotland
kommando Offline
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The 850 carb specs are

73-74 850 (with reversed cones)932/29-30 260 25 3.5 2
73-74 850 (with black caps)932/31-32 230 25 3.5 2 or 3
74 850 932/35-36 260 25 3.5 3
74 850 932/33-34 220 25 3.5 2
75 850 932/33-34 230 25 3.5 1 or 2

As for the stepped cutaways never having a MK1 or MK2 850 it may have been a all 850 change but

http://www.inoanorton.com/docs/TheNortonCarburetor.pdf

refers to Both 30 mm (type 930) and 32 mm. (type 932) bores were used at times on both the 750 and 850 motors. In addition, two types of spray tubes were fitted over the years. This is the brass tube which projects up into the center of the bore. Later 850's had a notch cut off the inside surface of this tube.

So does
Quote:
later 850's
mean all 850's or Black air box 850's, the parts books LAB refers to would suggest all 850's

Re: premier carbs [Re: kommando] #569295
10/27/14 2:30 pm
10/27/14 2:30 pm
Joined: Mar 2006
Posts: 3,657
Norfolk, UK
L.A.B. Online content
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Originally Posted By: kommando

http://www.inoanorton.com/docs/TheNortonCarburetor.pdf

refers to Both 30 mm (type 930) and 32 mm. (type 932) bores were used at times on both the 750 and 850 motors.


That sentence is slightly misleading or wrongly worded, as it tends to suggest 930 and 932 carbs were used on both the 750 and 850 models when as far as we know only the 932s were fitted to 850 models although 750 models did use both sizes, and 932s fitted to 750s (932/19&20 and 932/26&27) are not the subject of the discussion here.
Unfortunately, the INOA list doesn't include the relevant spray tube and needle information for each individual build spec., whereas the AMAL list supplied by Burlen does, and 932/29-36 are all listed as having the 928/107 stepped spray tubes and 928/104 needles.




Originally Posted By: kommando
In addition, two types of spray tubes were fitted over the years.

This is the brass tube which projects up into the center of the bore. Later 850's had a notch cut off the inside surface of this tube.

So does
Quote:
later 850's
mean all 850's or Black air box 850's, the parts books LAB refers to would suggest all 850's


It is often thought that only the black airbox 850'A' models (and 850 Mk3) had the stepped spray tubes, however the available information doesn't seem to support that.
In addition to the AMAL build list and the absence of any flat topped spray tube and 2-ID needle being listed in the '73 and '74 parts books, the factory manual for '73 750 & 850 has no information relating to the black airbox 'A' model, however only the stepped 928/107 spray tube and /104 needle are listed in the carb specifications for '850' along with '260 main jet', etc..

http://www.classicbike.biz/Norton/Repair/70up_Commando/70upCommando.pdf

Re: premier carbs [Re: SEATTLE GS] #569311
10/27/14 4:59 pm
10/27/14 4:59 pm
Joined: Aug 2001
Posts: 1,264
Hamilton, Mass. USA
D
Dave Comeau Offline

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Hamilton, Mass. USA
Can't say I have ever seen an 850 without stepped spray tube except for guys using the generic 300/301 replacements. I surmised that the original requirement for the stepped tube was primarily due to the more free flow balanced exhaust...
Well if you replace with 750 style pipes then a straight spray tube would make sense...


dynodave
BSA 3 1961-1963
Ducati 3 1992-2002
Norton many 1951-1975
87 Serv-Equip 100HP MC brake dynamometer,
Re: premier carbs [Re: SEATTLE GS] #569360
10/28/14 12:13 am
10/28/14 12:13 am
Joined: Sep 2009
Posts: 632
SEATTLE WA
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SEATTLE GS Offline OP
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A FEW MORE DETAILS...This concerns a MK3 WITHOUT the airbox. Just K&N

earlier reverse cone muffs, not stock black caps.

The carbs that arrived at my door step came with

#3 slides

straight tube spray tube

2-ring needles

Excellent for a Bonneville but ??? for a Norton.
Send them back? If nothing else the slides seem too rich. What is the jetting for a 1974 850?

Re: premier carbs [Re: SEATTLE GS] #569378
10/28/14 5:44 am
10/28/14 5:44 am
Joined: Dec 2004
Posts: 9,332
Scotland
kommando Offline
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Quote:
What is the jetting for a 1974 850?


Main/pilot/slide/needle postion
74 850 932/35-36 260 25 3.5 3
74 850 932/33-34 220 25 3.5 2

260 for reverse cone, 220 for blackcap silencer

Re: premier carbs [Re: SEATTLE GS] #569381
10/28/14 6:03 am
10/28/14 6:03 am
Joined: Mar 2006
Posts: 3,657
Norfolk, UK
L.A.B. Online content
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Originally Posted By: SEATTLE GS
A FEW MORE DETAILS...This concerns a MK3 WITHOUT the airbox. Just K&N

earlier reverse cone muffs, not stock black caps.

The carbs that arrived at my door step came with

#3 slides

straight tube spray tube

2-ring needles


Sounds like you've may have been sent a pair of generic 932 300/301 carbs?
Do they have the necessary machined flats to fit a Commando?
What size are the main jets?

Originally Posted By: SEATTLE GS
Excellent for a Bonneville but ??? for a Norton.
Send them back? If nothing else the slides seem too rich.


The slides could possibly be too rich, the spray tubes and needles can be changed if necessary.

Re: premier carbs [Re: SEATTLE GS] #569454
10/28/14 3:54 pm
10/28/14 3:54 pm
Joined: Sep 2009
Posts: 632
SEATTLE WA
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the carbs have not been shaved so they are generic but sold with the idea that they have been jetted for Norton. Main jet is 260.

Anybody have a factory manual for an 74 Commando? What are the jetting specs?

Re: premier carbs [Re: SEATTLE GS] #569456
10/28/14 4:00 pm
10/28/14 4:00 pm
Joined: Mar 2006
Posts: 3,657
Norfolk, UK
L.A.B. Online content
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Originally Posted By: SEATTLE GS
Anybody have a factory manual for an 74 Commando? What are the jetting specs?


There is no '74 factory manual, the specs. for '74 are as kommando posted previously.

Re: premier carbs [Re: SEATTLE GS] #569570
10/29/14 11:00 am
10/29/14 11:00 am
Joined: Dec 2011
Posts: 55
California, US
P
Peter_Joe Offline
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California, US
Originally Posted By: SEATTLE GS

Anybody have a factory manual for an 74 Commando? What are the jetting specs?


Here is a page from my Norton 850 Commando Mark 2/2A Riders manual (p/n 065321)that lists the carburetor settings. As a matter of fact this is the only place in the whole rider's manual that the Mark 2 or 2A is even printed. Everywhere else in the manual it just refers to the 'special noise control models' or the 'not-special noise control models'.


Re: premier carbs [Re: SEATTLE GS] #569648
10/29/14 9:45 pm
10/29/14 9:45 pm
Joined: Sep 2009
Posts: 632
SEATTLE WA
S
SEATTLE GS Offline OP
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SEATTLE WA
Thanks for the info.

Re: premier carbs [Re: SEATTLE GS] #569708
10/30/14 3:03 pm
10/30/14 3:03 pm
Joined: Aug 2011
Posts: 31
Western North Carolina
J
johnhannah Offline
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Western North Carolina
We installed a set of AMAL Premier carbs on a 73 850 Commando and a 72 750 Commando Combat this summer. Both use 932s but are set up differently.The 850 carbs arrived with a 3.5 slide, pilot RJ17, NJET 106 and main jet 260.These had the proper stepped cutaway spray nozzle.With the clip on the needle in the middle and the pilot mixture screw out 1 turn they are perfect. The Combat setup came with a 3.0 slide and 230 main jet. We had trouble with excessive popping on idle till Len figured out the problem after looking at the original carbs. The original carbs had the blank casting for the slide adjustment screw on the inboard side of the carbs notched to allow a close fit on a Commando. On the Combat motor the carbs were touching and not allowing a proper seal with the manifold. A bit of minor machining on the bodies and all was fine. No more popping and they adjusted properly.These carbs transformed both bikes and a steady 1000 rpm idle is excellent.

Re: premier carbs [Re: SEATTLE GS] #569728
10/30/14 5:57 pm
10/30/14 5:57 pm
Joined: Oct 2007
Posts: 159
Belgium
7
79x100 Offline
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Belgium
All standard Commando carbs originally had the unused boss machined off and non-specific replacements need a file taking to them.

Do the Premiers for Commandos have the small holes drilled where the tickler tubes insert...and what was it for anyway ?


'39 WD16H
'75 850 Commando
Re: premier carbs [Re: SEATTLE GS] #569731
10/30/14 6:37 pm
10/30/14 6:37 pm
Joined: Mar 2005
Posts: 10,131
Boston, Massachusetts
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John Healy Offline
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Quote:
and what was it for anyway ?


Vent!


Re: premier carbs [Re: 79x100] #569733
10/30/14 7:22 pm
10/30/14 7:22 pm
Joined: Mar 2006
Posts: 3,657
Norfolk, UK
L.A.B. Online content
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Originally Posted By: 79x100

Do the Premiers for Commandos have the small holes drilled where the tickler tubes insert
...and what was it for anyway ?


I think AMAL dispensed with the vent holes when they started fitting the extended 'waterproof' ticklers, so from around 1973?

Re: premier carbs [Re: L.A.B.] #569741
10/30/14 7:53 pm
10/30/14 7:53 pm
Joined: Oct 2007
Posts: 159
Belgium
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79x100 Offline
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Originally Posted By: L.A.B.
Originally Posted By: 79x100

Do the Premiers for Commandos have the small holes drilled where the tickler tubes insert
...and what was it for anyway ?


I think AMAL dispensed with the vent holes when they started fitting the extended 'waterproof' ticklers, so from around 1973?


I don't know. I thought that the 932 R33 (and L34 ? but I can't see that one) were original to my Mk3 and that they always had 'waterproof' ticklers. What puzzles me is that the hole seems to be completely closed by the tickler tube so I can't imagine where any breather function arises.


'39 WD16H
'75 850 Commando
Re: premier carbs [Re: 79x100] #569747
10/30/14 8:26 pm
10/30/14 8:26 pm
Joined: Mar 2006
Posts: 3,657
Norfolk, UK
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Originally Posted By: 79x100
What puzzles me is that the hole seems to be completely closed by the tickler tube so I can't imagine where any breather function arises.


With the waterproof ticklers, the vent isn't needed because the float chamber vents through the tube. With short ticklers I think there's a chance the tip of the rider's finger can close off the drilling when the tickler is pressed fully down which would result in an airlock if it wasn't for the vent.

Edit: Looking at various period photos it seems AMAL continued to drill the vent hole until around 1976-'77 possibly because it appears that Triumph didn't adopt the waterproof ticklers until then? The 'believed original' 930s fitted to my '78 T140V don't have the vent holes.

Last edited by L.A.B.; 11/02/14 8:49 am. Reason: Additional info.
Re: premier carbs [Re: L.A.B.] #569847
10/31/14 4:12 pm
10/31/14 4:12 pm
Joined: Oct 2007
Posts: 159
Belgium
7
79x100 Offline
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Thanks, L.A.B. That all makes sense. I enjoy these odd differences even if I can't always see the point of them...I wonder who first coined the term 'waterproof' for the shrouded ticklers ('cause they ain't !)


'39 WD16H
'75 850 Commando

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