The BSA A7-A10 Forum

Technical (Descriptive Topic Titles - Stay on Topic) => Amal, Carburation, Fuel => Topic started by: mario medeiros on 02.12. 2013 12:52

Title: concentric carb on a10?
Post by: mario medeiros on 02.12. 2013 12:52

Have a 1957 a10 i just bought and i know it is to have a mono block carb but someone replaced it with a concentric and i just wanted to ask which one will work on my 650?And does a concentric work well on a a10?Thanks

Title: Re: concentric carb on a10?
Post by: muskrat on 02.12. 2013 18:52

G'day Mario.
I don't have one on an A10 but I do have a 932 on my '51 A7 (with a '57 SS top end) and a friends '52 A7 ST has a 626. Both work quite well once jetted correctly. The cons do suffer with a sticking slide if the mounting nuts are too tight. They don't suffer from altering idle speed when on the side stand or upright.
Cheers

Title: Re: concentric carb on a10?
Post by: Billybream on 02.12. 2013 19:13

Hi Mario.
I have Mk 1 type 900 concentric on my Super Rocket, been fitted since 1970. Just overhauled with new stayup float and needle valve kit. No running issues to report.
Burlin Fuels is great web site for Amal : http://amalcarb.co.uk

Title: Re: concentric carb on a10?
Post by: Seabee on 02.12. 2013 20:33

Hi Mario,

I have one on my 57 RR and it works well.  I only have the tickler for cold starts, so on a really cold day it can be a bugger to start!

Seabee

Title: Re: concentric carb on a10?
Post by: mario medeiros on 03.12. 2013 00:11

Hi Seabee,what kind do you have?as far as a model number,thanks

Title: Re: concentric carb on a10?
Post by: Topdad on 03.12. 2013 12:11

I've had a concentric on my A for over 7yrs and it hasn't ever caused a problem, BobH.

Title: Re: concentric carb on a10?
Post by: Seabee on 03.12. 2013 12:57

Sorry Mario, it's a 932.  Not sure on jetting as it was on the bike when I bought it and ran so good I left it alone!  I do wish it had a choke as my concentric does on my 61 A10.

Title: Re: concentric carb on a10?
Post by: Duncan R on 03.12. 2013 17:00

Mine also runs a concentric with no issues - Seabeee, if you are not allready aware you can reto fit a choke I got all the parts from Burlin fuels. Didn't seem to make much difference though.

Cheers

Duncan

Title: Re: concentric carb on a10?
Post by: taroha10 on 03.12. 2013 21:17

My super rocket also runs fine on a concentric. It doesn't like ticking over on the side stand but to be honest I haven't spent any time trying to find out why. Not sure off the top of my head what size or jetting it has.
Good luck with it.
Mark

Title: Re: concentric carb on a10?
Post by: Ted_Flash on 04.12. 2013 07:45

My '50 GF has a concentrric 928, no.3 throttle valve, needle position 1, needle jet 106, main jet 220, no filter, 356 cam.

It runs clean all the way through the rev range, and have checked with colourtune plug.

Title: Re: concentric carb on a10?
Post by: victortrry on 03.06. 2014 07:23

I have tried to fit a 930 concentric on my 54GF but it is too tall, how does it fit on s 50GF?

Title: Re: concentric carb on a10?
Post by: muskrat on 03.06. 2014 09:53

G'day Victor.
Is that a 930 Mk1 or a 2930 Mk2 concentric? I'm sure the 930 will fit, not sure of the 2930.
Cheers

Title: Re: concentric carb on a10?
Post by: victortrry on 03.06. 2014 10:37

Mark 1 concentric, its too high.

Title: Re: concentric carb on a10?
Post by: olev on 03.06. 2014 10:53

Musky,
I have a 52 A7 ST (work in progress) - probably the same as your mates.
Can you ask him if he wrote down the jetting etc for his 626.
I'm assuming it doesn't have an air cleaner
Was contemplating using a keihin type JRC but might hunt down a 626 after reading this.
I've got a 930 working well on my greeves. Havent had any luck in the past with mikunis.
cheers

ps. serious game of footy the other night. hey!

Title: Re: concentric carb on a10?
Post by: Ted_Flash on 03.06. 2014 12:02

Quote from: victortrry on 03.06. 2014 07:23

I have tried to fit a 930 concentric on my 54GF but it is too tall, how does it fit on s 50GF?

Fits fine, about an inch clearance to the frame.  I can't get the slide out with the carb in situ, but there's no problems with the cables.

Should have mentioned - flat top 7.25 pistons fitted.

Title: Re: concentric carb on a10?
Post by: muskrat on 03.06. 2014 20:40

Victor, plunger or SA, iron or alloy head? I know there's a problem fitting a concentric to a A10 plunger with alloy head. No problem with an A7 plunger & alloy head.
Olev, I'll be giving it a service next week. I'll have a look.
Cheers