Author Topic: Amal Carb  (Read 1041 times)

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Columbia13

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on: October 31, 2021, 05:41:53 pm
Hi, I have a 2008 350 cast iron which has a 626 Amal mk1 concentric carb on it. With a Hitchcocks S&B pancake air filter and a standard exhaust. Could anyone please recommend what number main jet I should have in and what position the throttle needle clip should go on. thanks in advance Michael


Karl Childers

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Reply #1 on: November 01, 2021, 04:03:37 am
The  replacement air filter will only have so much effect on performance and overall air flow if you are still running the stock muffler I don't think it would need drastic changes unless you are starting out with an unknown replacement carburetor.  How is the bike running at the moment? Is it OK or running lean or rich? what elevation are you at? A location that is arid or humid? all of these things will effect what jets to use and what needle setting is needed. More information would be helpful to get yours dialed in.

https://www.oldbritts.com/amal_tun.html
« Last Edit: November 01, 2021, 04:09:35 am by Karl Childers »


Columbia13

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Reply #2 on: November 01, 2021, 02:50:32 pm
It ran reasonably well considering, but it was rich.
The flange was bent and the slide was sticking (I have now sorted this out)
The clip on the throttle needle had somehow wound itself up past the first coil of the spring, so the needle wasn’t going all the way down.
I’m going to replace the spring, needle and clip with new parts that’s why I wanted to check the main jet number while I’m at it, it currently has a 160 fitted.
I’m in the UK so it’s always cold and damp, at least it is hear in the North East!

P.S. if I fit an insulating gasket, such as the phenolic type supplied by Amal, should I leave the flange O ring in place or remove it?


Karl Childers

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Reply #3 on: November 01, 2021, 05:28:33 pm
It sounds like the needle clip situation was a be big contributor to the problem I would put the needle at the lowest setting and see how it runs in the half throttle range, you'll probably be OK with the 160 main so try that first with the needle dropped, 3/4 to full throttle should tell if you  should go down a size or two on the main jet or stay with what you have. Jets are cheap for Amal's I would pick up a few sizes to experiment with. My preference would be gasket only for the carb flange, if the surface is smooth and truly flat, don't over torque the mounting nuts and it should seal well.


Columbia13

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Reply #4 on: November 01, 2021, 07:41:45 pm
Thanks Karl, your advice is much appreciated.