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Amal concentric carb fitted to BSA M20 - correct settings?

Hi,

I have a 1943 BSA M20 and a previous owner has fitted an Amal 626 concentric carb to replace the original. Does anyone know what settings would be correct for this carb on an M20? Has anyone fitted a 626 conentric to the same bike? I figure there were probably lots of people who did this when the original carb was no longer serviceable, so someone must have done the numbers already...

Cheers,

Carl

email (option): carlrholm@gmail.com

Re: Amal concentric carb fitted to BSA M20 - correct settings?

Use the same settings as for a monobloc...You will find those in 1954 and onwards manuals/handbooks...

The concentric and monobloc carbs function and are set up in exactly the same way, in fact the main jets are dimensionally identical...I've used pre monobloc, monobloc and concentrics (MK 1 and 2) over the years for various bikes and they are all interchangeable if correctly specified and set up for application....

Note however that the spec. and settings laid down by BSA and Amal are only intended to get the bike running in the right area...You may still have to adjust needle settings, pilot air settings (from the base line 1-1 1/2 turns out from fully closed) to get everything running perfectly, due to the production and wear variations of the individual machine...Ian

Further to the above...Monobloc settings....

Choke size 1" (25.4mm)
Main jet 240
Slide cutaway No 5
Needle position 2 (the middle one on a concentric)
Needle jet .1065 (these are usually 106s these days as the 'half' sizes aren't generally available)

The slight difference in choke size between 25.4mm and 26mm will make no practical difference to jet sizes...

email (option): ian@wright52.plus.com

Re: Amal concentric carb fitted to BSA M20 - correct settings?

From a previous discussion on this topic

http://pub37.bravenet.com/forum/static/show.php?usernum=3155626639&frmid=16&msgid=1243423&cmd=show

email (option): bsansw1@tpg.com.au

Re: Amal concentric carb fitted to BSA M20 - correct settings?

Thanks Ian, that's very helpful of you!

email (option): carlrholm@gmail.com

Re: Amal concentric carb fitted to BSA M20 - correct settings?

Thanks, Trevor.

email (option): carlrholm@gmail.com

Re: Amal concentric carb fitted to BSA M20 - correct settings?

For the past few years I use a concentric 626 with a number 3 slide

John

email (option): john.kater@chello.nl

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