Base settings after Amal rebuild

After a complete overhaul/rebuild of the 900 series Amals off of a 74' Commando, meticulous ultrasonic cleaning, bead blasted, new rebuild kits etc. I am asking if there is any variable off of the recommended adjustments I should be aware of or you used successfully.
In the past I have taken on a variety of SU's, Holley's, and other makes but never Amal carbs. I say this only to offer up I do have a clue about carb rebuilding.

If you have any insight toward settings of the needle position, and both air and idle screw setting positions off the given norm or other than the Amal settings for initial startup I sure would like to hear what your initial settings were.

I have reassembled these carbs in accordance with the Amal offerings and literature but am curious as to what others have encountered or adjusted upon initial attempt at starting.

Thanks in advance guys.


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I have found the factory settings per the owners/service manual to be pretty much on the money - at least on a stock 850. Very minor adjustments either way - less than 1/4 turn on the air screw from spec - optimizes the idle mixture. Needle position, etc as per stock. Obviously main jet size will need some sorting if you are not at sea level and possibly if you are using non-stock items - like the air filter in your pics or other than the stock manifolds/mufflers.

I don't know if you did this but one of the most critical thing in reworking a set of old Amals is to ensure that all the mating surfaces are true - carb surfaces, carb to manifold surface and manifold to head surface. Unless this was done recently, they are not and all sorts of niggling issues can arise from the fuel/air leaks that result. Over tightening the carb and the carb/manifold fasteners can warp the bodies and also cause the side to stick. Of course the slides/bores must be in good shape and there are several companies who can resleeve them /add better slides. New Amal Premiers come with the better slides. All the mating surfaces can be trued with some wet/dry sandpaper on a sheet of 1/4" glass or other suitable FLAT surface. Use a figure 8 motion of the part on the paper. Properly restored Amals will idle smoothly on the Commando at very low RPM - much lower than you will actually set the idle.

Despite all the common "Amals suck!" views, I have found them to be excellent carbs when in good condition. IMO, most of the Amal bashing that states "Mikuni's (or whatever) are much better" is based on comparing a pair of 40 year old Amals in clapped out condition with a new Mik or other carb. Hardly a fair comparison. Also if anyone tries to tell you that a single Mik (or whatever) carb is "better" than a pair of Amals, challenge them to a drag race for pink slips - but first ensure you have space in your garage for another Commando.

To be fair, ONE carb is easier to adjust than two and, for practical daily use, the single Mik works great. It's only at higher speeds - say 75MPH+ - if you go to WOT that the difference is noticeable.

Agree. But Id say better value to simply purchase a new pair of Amal Premmies than to over haul what you have. By the time you are finished you
have saved much and an overhauled original amal isnt as good. That is how it worked out for me.
My experience with 750 Triumph is the same as your one or two carbs argument. For normal riding the single carb is probably better. It just doesnt
look as cool!

Totally agree with: 1 Buying new Premiers and, 2. No way any single (frankly I'd say ANY other carb, single or dual) looks as cool as a pair of Amals with the OEM cheese box filter box.

FWIW this is what I found out from personal experience..

1) Onder was correct when he said it was probably better and more cost efficient to get a new set of Premieres instead of buying all the upgraded parts to rebuild the old ones.
2) Never over tighten any of the screws or nuts. I use purple locktite and just nip them up till the spring washers compress.
3) If you have removed the bean can mufflers I am willing to bet you can go with #3 slides or even spec out your carbs to “pre emission standards”. I have a pretty stock 850 and found the #3’ adds a lot to the mid range.
4) Make sure you float levels are equal on both carbs.
5) Spend a little extra time and make sure they are sync’ed perfectly.
6) Depending on where you live chokes may not be necessary.
7) As also mentioned make sure all mating surfaces are flat. If the surface that goes up against the manifold appears to be bowed just don’t sand it down on a plate of glass. That might be a sign the bodies are distorted. There is an article some where that describes how to straighten out the bodies.

I probably missed some stuff but reading Bushman’s carb setup info will cover the rest
Pete