The BSA A7-A10 Forum

Technical => Amal, Carburation => Topic started by: owain on 05.01. 2019 18:07

Title: Concentric carb recommendation for a 1950 plunger A10
Post by: owain on 05.01. 2019 18:07
I'm thinking of buying a new concentric carb for my 1950 A10 plunger which is running original 6v dynamo/mag. It originally had an AMAL 276 but I swapped that to a used AMAL concentric carb that I bought at an autojumble. The issue is that I think the concentric is pretty worn out as it's not providing consistent performance.

Does anyone have a recommendations for the correct sized concentric carb for an iron head 1950 A10? It'd also be super appreciated to know what jettings/ needle positions your running in an A10 with a similar carb setup?

Many thanks!
Title: Re: Concentric carb recommendation for a 1950 plunger A10
Post by: Triton Thrasher on 05.01. 2019 19:36
What size is the inlet you want to bolt it onto?
Title: Re: Concentric carb recommendation for a 1950 plunger A10
Post by: edboy on 05.01. 2019 19:42
hi, i m running with concentric 28mm size.
needle top, 3 1/2 slide and 240 main [ poor memory ] for main jet.
you can ditch the air filter as well if you like as makes no difference to performance
Title: Re: Concentric carb recommendation for a 1950 plunger A10
Post by: worntorn on 05.01. 2019 22:39
If it makes no difference to performance, why not keep the air filter?
Having a filter in place definitely increases the life of the rings, bore , pistons and also carbs.

Glen
Title: Re: Concentric carb recommendation for a 1950 plunger A10
Post by: muskrat on 06.01. 2019 03:59
On a plunger with a concentric I don't think the rubber connector will fit. It won't on my A7 plunger. It's a 900 series, don't know about the 600 series.
Cheers
Title: Re: Concentric carb recommendation for a 1950 plunger A10
Post by: WozzA on 06.01. 2019 04:41
I'd also be interested to know what size Concentric & jettings ?   *????*
My '51 plunger's 276 is just not doing the job.. 
Title: Re: Concentric carb recommendation for a 1950 plunger A10
Post by: Simon59 on 06.01. 2019 15:35
I'm also very interested... the 276 carb that came with my A10 plunger 'barn find' is pretty worn so I would be keen on fitting a Concentric instead, as they are quite a bit cheaper!
Title: Re: Concentric carb recommendation for a 1950 plunger A10
Post by: Rex on 06.01. 2019 16:03
Can't help with an A10, but my recently completed A7 (1951) ended up with a 200 main jet, a 3 slide and the needle in the bottom groove. Amal Premier running with a bell mouth as the air filter components were missing.
Title: Re: Concentric carb recommendation for a 1950 plunger A10
Post by: edboy on 06.01. 2019 18:07
there are dumpy gauze bellmouths for concentrics available that squeeze in between the frame. handy if you dont have an original airbox and are using the enfield 6v battery carrier instead.
if you luckily own the original air box then keep the air filter. your choice.
Title: Re: Concentric carb recommendation for a 1950 plunger A10
Post by: morris on 06.01. 2019 18:50
My ‘52 A10 plunger is running great on a concentric 928 (came with the bike)
It just runs a tad lean on the pilot which I am planning to replace by a 25 on the first occasion.
Actual settings;
20 pilot
3 1/2 air slide
106 needle jet (needle position 2 from top)
250 main
Title: Re: Concentric carb recommendation for a 1950 plunger A10
Post by: WozzA on 07.01. 2019 02:01
Thanks morris...  I've been thinking about what fits .. thats a great help should I have to go down the carb replacement  track.. *wink2*
Title: Re: Concentric carb recommendation for a 1950 plunger A10
Post by: owain on 07.01. 2019 13:02
Thanks for the replies. The worn 930 concentric seems to fit fine on the '50 plunger. Although a little cramp. I'll put a new 928 on the shopping list and give it a go. The inlet size on the 600 series seem to be abit too small e.g. 26mm. I was also thinking of saving a few quid with a Wassell instead of Amal...some people say they work fine and others say that they are poorly made though :/