Return to Amal Mk1 Concentrics

Hi chaps - after being rather dissapointed with a single carb on my 920 Mk 2A I've decided to go back to a pair of good old 32mm Mk1 Amal Concentrics (OK I know they wear like hell and are made of monkey metal but they are what was specified originally - probably because that was all there was - - ) but they did work well. I'm getting on a bit now and I need a motor that starts easily ( at present it's very hit-and-miss). I'm looking at 2 x 32mm units with choke slides but no air filters to start with - I won't bore you with the details - - - Ignition is cock-on via Tri-Spark Classic Twin.

Any advice ???

Cheers

Twin carb abvice? Would you consider a setup that did not come as stock 40 years ago?

http://www.jsmotorsport.com/products.asp

http://www.jsmotorsport.com/technical_Carbs.asp

scroll down the page a little, two 32mm flatslides all prejetted and come complete, everything, and they are magnificent, they have chokes, start easily, idle like a rock all day, and just plain flow, to me they feel much more responsive and stronger metered flow than the twin amals I replaced them with. I will never go back.

And no, I have nothing to do with Jim Schmidt, I just really like his flat slides for my commando

I have the twin 32mm Amals on my '74 with Tri-Spark ignition and they work very well. You will get all kinds of advice about how to use a different set-up from the one you've chosen, but you'd like to use the Amals. I bought a set of new ones from Baxter Cycle to replace my worn ones. I did need to do a bit of fiddling initially, but they have been fine for about 3,000 miles.

I first placed them on the bike with the main needle in the centre position, then adjusted the idle when warm. I synced them using the "drill-bit method". After riding it a little and fouling the plugs, I altered the needle position and reset the idle. It now starts half-way through the first kick every time (flooding if cold, none if warm) and immediately idles at 900 - 1000 rpm without need for me to rev it. I've even stopped using the choke slides when cold.

Best of luck - it can be done!

Paul.

Good choice I would say. I run 30's I think and have 35k miles on them. Don't believe the myth about all of them needing re sleeving. It is just a way for them to relieve you of some hard earned cash. Come to think of it there seems to be a number of myths regarding our bikes. But, thats what makes the world go round.

I used to use the drill bit method, or use my eyes etc.
I now unscrew the idle screws & hold it on the cables. If one side is firing harder, adjust the cable on the other side to give it a bit more throttle until firing evenly. Saves me dismantling anything. Seems to work for me.

1up3down said:

Twin carb abvice? Would you consider a setup that did not come as stock 40 years ago?

http://www.jsmotorsport.com/products.asp

http://www.jsmotorsport.com/technical_Carbs.asp

scroll down the page a little, two 32mm flatslides all prejetted and come complete, everything, and they are magnificent, they have chokes, start easily, idle like a rock all day, and just plain flow, to me they feel much more responsive and stronger metered flow than the twin amals I replaced them with. I will never go back.

And no, I have nothing to do with Jim Schmidt, I just really like his flat slides for my commando

Click to expand...

These sound interesting, how much work was it to set them up? I have a single Mikuni now but think it might be sapping some of the power that the motor could be developing. Sweet running is more important than power to me, but I hate to give anything away!

Vintage Paul

I too am happy with the JSMotorsports PWKs which replaced a set of stock but badly worn Amal 32s. JSMotorsports supplies everything you need for the swap and the post-sale support is exemplary.

Fitting flatslide carbs will mean increased performance and economy, smoother running, and no need to sleeve them due to very rapid wear of shoddy pot metal component parts.

My 2 cents. Re-sleeved Amal is a cost effective carb solution for a Commando.
No big bucks needed, easy to tune and works well when correctly set up.
In my opinion they provide easy starting, solid idle, good fuel effeciency and runs well.
On the negative side is the sensitive idle circuit but it is relatively easy to clean if needed.

Yes it is old stuff but so is the rest of the bike and that is why I like it

Per

Jim Schmidt is selling the complete dual flat slide set up for $445, includes cables, manifolds, filters, etc etc

I don't know how much new amals are, or manifolds, but I thought the flat slides were very reasonable

Why buy new Amals, get used ones and re-sleeve.
I have friends running the same re-sleeved Amals for over 10 years and they ride a lot!

And NO, I do not work for or get paid by anyone doing re-sleeve service.

Per