Amal Needle decoding

I have a pair of Amal 932/029 MK1 carbs on my 1973 850 Commando, and I want to replace the oem needles, needle jets, and main jets. I went to the Amal order website and the number coding for needles only indicates 622/124 for 4-stroke needles, and 622/278 for 4-stroke special needles. Did Amal re-assign
a revised numbering system for the needles, as I cannot see the 928/104 needles that my shop manual states is the right replacement needles, or should I try to find needles 928/107, as stated in Jerry Doe's technical page?
I am going to replace the .106 needle jets with same, and 260 main jets with same.
Although the engine idles well, runs smooth and pulls strong, my right-side header is dark, dark blue at first bend, while left-side header is gold/very light blue at first bend. Headers are singular, not joined, 11/2 inch English Wassel's which were installed last year, and the discoloring started almost immediatly. Float levels were correctly adjusted for both carbs this season. Airfilter is stock paper, and using reverse-cone peashooter silencers. I checked for any intake air leakage with carb cleaner spray, and wd40, with no leakage apparent. All o-rings on carbs were also replaced with new.
I'm assuming right-side is running leaner that left-side, hopefully replacing both carbs with new needles and jets will even up the mixtures.
Thanks

I'm not sure how to identify the carb body by p/n but the choice of needles is 622/124 for the shorter needle with 2 ident rings or 928/104 for the longer ones with 4 ID rings. The 928/104 needles are used with later carbs having the cutaway spray tube.

Running lean on one side can be a warped carb flange, loose manifold mounting, or plugged pilot jet. Worn needle and jet tend to make things richer, not leaner.

singring said:

I cannot see the 928/104 needles that my shop manual states is the right replacement needles, or should I try to find needles 928/107, as stated in Jerry Doe's technical page?

Click to expand...

You won't find any "928/107" needles. That's a typo unfortunately, as 928/107 is the stepped spray tube (note the double entry-I will inform Jerry).

Check the top of your needles, there should be either 2 or 4-ID rings marked above the top clip groove?

As maylar said,the 928/104 4-ID ring needles are used with the stepped spray tubes, and 2 ID needles with the flat topped spray tubes.


622/278 is the special 5-ID ring T160 Trident economy kit needle, so Amal's listing is obviously wrong, as they list the correct 928/104 needle in their carb rebuild technical section.

http://www.amalcarb.co.uk/TechnicalDetail.aspx?id=11

You can find the 928/104 needle typing the part number into the express order box.

http://www.amalcarb.co.uk/ProductCatego ... arentId=48

singring
Why change your mains? This normally is a non wearing part.
CNN

I wouldn't worry about different coloured pipes. My left if dark blue & my right is golden yellow. You would be extremely fortunate to get them the same colour.

CNN, for aprx $10 for a set of mains, why not? The old ones could have oxidation deposits that are affecting flow.
Total parts and shipping will be aprx $52, also getting replacement brass fuel bowl drains.

Try doing a WOT plug chop with mains that you have. If plugs look good buy same. Find a suitable road fairly flat with a slight uphill grade so engine will be pulling and go WOT for a few seconds. Plug chop…then coast to stop with clutch in and inspect plug conditions. Black = rich White ash = lean. Tan… pretty close. Lots of info for Plugs on internet, but not this thread.
Also go again WOT for same time frame but then turn throttle back 7/8 ish…if engine speed increases then you need larger mains.
If you have money to burn then go up and down a size on the mains and play. Make sure there is no Buford T Justice Policeman looking out for you while you play or you will be singing a tune… “I don’t want a Pickle…I just want to ride my Motorcycle. :mrgreen:
CNN