Hi Guys, I intend to fit a pair of Premiers to my Mk.3 but not sure on jetting.
I have straight through peashooters but I need to replace the exhaust pipes, are the linked pipes or the straight through pipes better, and would either type affect the jetting?
I am also replacing the black box with a ham can filter.
I imagine all of the above could change the jetting, any advice would be greatly appreciated.
Previous post
A day or two ago, someone posted a detailed list of carb specs to suit my Mk 3 setup as stated above, but the post has disappeared!?
I was about to thank the person for the information, but now not able.
Was there a problem with the information given and I'm still looking for an answer to my question?
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The #19 pilot jets are a…
The #19 pilot jets are a great solution, and allow you good adjustment of the air screw.
Without #19s you are not able to use the 1 1/2 turns adjustment as your starting point for fine tuning (it's more like 1/4 turn with the #17, so not enough adjustment in my opinion)
I would advise you to go for the proper 932/42 and 932/43 carbs rather than the baseline 930/300 and 932/301 which are jetted by resellers.
The correct model for the bike has the correct notched spray tube (which is an absolute pain to retrofit), and the float needle bushing set to the correct height (which means you don't need to fight with bending the tangs on the float)
When you order from Amal, you can also ask them to use the 622/054 high flow float bowls, which are a worthwhile upgrade. These are not standard on the MK3, so you need to ask for them.
With peashooters and ham can exhaust, you will need to modify the jetting a little (removing the 850 balance tube makes negligible difference to carburation)
A 260 main jet and needle position 3 is a great starting point for setting it up.
I would recommend you consider the RGM narrow ham can kit - it makes life so much easier!
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Reply from Burlen
Grant, this is the reply I got back from Burlen/Amal after I specified exactly what you recommended. It looks a bit different!
Your thoughts?
PACK 113 is the part number for a set of 850cc Commando carburettors that contain all the parts you have mentioned in your email. The specification numbers of the carburettors in the set are 932/33 and 932/34.
They are supplied with 260cc Main Jets, 19 Premier Pilot Jets, .106” Needle Jets and 3 ½ Throttle Valves. They also use the correct spray tube and throttle needle for the 850cc Commando and the .125” seating high flow float bowls. The needle clips are set in the middle position as per the original Norton requirements but as the needle has to be removed to fit a cable you can adjust that when you fit cables.
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PACK113 is for a MK2a If…
PACK113 is for a MK2a
If they are recommending you go up that route, I am surprised they didn't recommend PACK138 - which is the US MK2.
MK2 had ham can and peashooters, compared to the MK2a which had the black box air filter and bean cans, so quite different.
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Mk3 with Peashooters and no balance pipe set up
1977 Mk3 set up - great results on this upgrade and set up - no flat spots - lots of power delivery - starts first time - great tickover etc.
Ok= Replace with as new AMAL CONCENTRIC R300/932
32mm carbs (Premier)
CURRENT SET UP
New carbs fitted December 2024
Pilot jet upgrades standard on Premier models.
Needle = 4 ring position 1 (top groove) Andover Norton suggest position 1 also
Main jet 260 Andover Norton suggest 260
Slide 3.5 anodised
Needle jet 106
Mixture screw 1 1/2 turns out Andover Norton suggest 1 1/4 turns out
Stay up float upgrade (resists ethanol).
Ally float needle upgrade Viton tipped (resists ethanol).
- Set slide into carb body (no cables) - adjust slide stop screw (tick over) so that both slides measure the same from top of carb body (no cap fitted) to top of slide body. This ensures that adjusting tick over is truly balanced / coordinated.
- Ensure that both choke slides are set the same and fully at the top of the carb body when the choke is off (cable is tight).
- Ensure that the slide bodies are both synchronised together by pulling throttle cable and both slide bodies reach the top of carb body at the same time.
- Set mixture screw to 1 1/4 turns out as a starting point for adjustment.
- Adjust mixture screw to result in maximum tick over for each carb.
- Adjust tick over (slide stop) to give required tick over - ensure that you apply same adjustment to both carbs so as to maintain the balanced / coordinated set up from stage 1 above
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Thanks Grant, I will ask the…
Thanks Grant, I will ask the question, your suggestion certainly seem to make more sence.
Brian, thanks for your advice. I wasn't going fit the chokes, just tickle the carbs on a cold start.
your thoughts?
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Reply from Amal
Here is the reply I got from Amal, your thoughts Grant?
Dear Mr Finlay,
PACK 113 is the only set of 850cc Commando carburetters which use the .125” high flow float needle seatings as standard. It contains 932/33 and 932/34 which are the carburetters listed in the Norton Parts List for Mark 3 850cc Commandos beginning with engine number 325001. We will have to change the Main Jets to the 260cc size you requested but otherwise these match the specification you detailed in your initial e-mail.
Kind Regards,
Phil Beresford
Technical Sales Advisor
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I think we are being victims…
I think we are being victims of parts consolidation!
The MK3 uses PACK114 which consists of 932/42 and 932/43
...I'm probably just knit picking at this point - I hate it when the supposed experts tell you something different to what's in print and is displayed on their own website for no other reason than to suit their own narrative.
I guess it doesn't matter provided they are speccing your new carbs to accommodate the changes you're making.
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I use the set up below on…
I use the set up below on MK3 that is close to the OP.
#19 pilot
106 Needle Jet
260 Main Jet
Cutaway spray tube
Needle on weakest setting.
The above assumes peashooters, no balance pipe and the one thing many above forgot to mention, no ventruri's in the black airbox.
The above is the jet pack supplied for the early 850 - carb pack 136. The use of the Hi Flow needle seatings in pack 113 is beyond me when the pack uses a 220 main, mind you a lot of what Burlen do is beyond me.
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Hi, I got my premiers direct from Amal (Burlen Ltd) they sent mine jetted to the specification of my Commando. A great improvement on the original concentrics, which to be fair were probably worn!