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[ExREEFI]

I've converted my 09 C5 with the Amal Mk1 kit. It looks great and i'm happy with the result.

A question for Amal gurus if I may? I've removed the air slide - it does nothing here in Oz where we don't get very cold weather and it's one less cable to run. The cable entry has been blocked with a bolt and some silicon. Just wondering if the missing air slide causes any issues given it leaves a fair size gap in the internals? Sometimes the bike will stall when running to a stop. The idle isn't set very low, about the same as the EFI was. It seems wrong to have an Enfield idling at Japanese single rates.

[Thack]

I've experimented with leaving out the air slide, and can honestly say it made no perceptible difference at all. Certainly it didn't cause any tendency to stall in the way you describe. I think you'll be just fine. I should point out that the Mk1 is a very crude carburettor, and you might end up having to live with that stalling. However, I bet you can mitigate it a lot by tweaking the tickover mixture one way or the other. I'd experiment - nothing to lose. Meanwhile, you're happy you have no air leaks anywhere?

[mauri]

shhhhhhhht thack, don't say that the mk1 is a crude carb.
this is a pro amal board.

this equates to:

the mk1 is good
the monobloc is even better
the pre monobloc is simply the king of carb's
the GP is in a class of its own, it simply out performs anything existing period.

now put yourself in a corner for at least half an hour.

[Gwilly]

I'm no Amal guru but a brand new Amal mk1 should be fairly good to tune and use..

Go back to the basic procedure, adjusting pilot screw and throttle stop (warm engine) until a nice even tick over obtained..

As a rough guide less than one turn out on the pilot screw means you have a possible air leak at manifold or pilot jet too weak..

If more than two turns out then possible pilot jet too rich or air filter restrictive..

The needle may need raising or lowering by one notch to fine tune mid range throttle, plug chops may help with full throttle main jet sizing but i expect its quite close to correct if supplied jetted by MrH..

You haven't mentioned if the exhaust has been changed or how the ignition timing is now set up..

[Thack]

LOL, Mauri! You are quite right - I won't win any friends by speaking my mind about Mk1 Concentrics!

[Thack]

Even though I'm a great fan of CERTAIN carburettors, I'm not sorry to see them go; fuel injection has the potential to be so much better, although it's obviously impractical for the average owner to alter the tuning.

[Presto]

Whatever comments may be made about the Mk1 Concentric being ‘made down to a price’ (which was true) or however ‘crude’ they may be compared with other more sophisticated (and much more expensive carbs) a short visit to the National Motorcycle Museum will demonstrate just how effective they can be when set-up correctly. The Museum houses dozens of the most noteworthy British bikes that were fitted with Amal Mk1s: road bikes of course but especially famous competition machines of all types: road racing, solo, sidecar, production racing, 'works', 'private', short circuit and TT; motocross; enduro; grass track; trials and so on and so forth. These were not 'also-ran' machines but machines that won their classes time and again. The proof and the pudding!...

[Thack]

Presto, I don't really find that a very convincing argument, because there weren't many alternatives to the Amal. Some, yes, but not many. And even if the Amal was the best of them, that was only because the others were even cruder (by today's standards). Many of the bikes you list had 6V Lucas electrics and brakes less effective than a brick on a string - that doesn't make them "good", merely that there was nothing better available at the time. The biggest improvements in carburation came with the Italians, Germans and Japanese: Del 'Orto, Bing, Mikuni, Keihin, et al. These are WAY better than the Mk1. Even Amal acknowledged this by bringing out the Mk2, which was essentially a Mikuni copy and a big improvement. The Mk1 may have been acceptable back in the '60s and earlier, but why use it nowadays when the Mk2 is readily available and so much better? The Mk1 belongs in the dustbin of history, along with the Monobloc, 6V electrics, incandescent rear lamps, etc, etc. Note: I am NOT arguing against using the Mk1 for purposes of historical authenticity. If that is important to you, then of course fit one. But to actually CHOOSE a Mk1 over a Mk2 as part of improving your bike seems daft to me.

[Presto]

This ‘discussion’ could go on and on and get nowhere. But just to add that I’m talking of bikes in the mid to late 60’s (I thought the Mk1 came on the scene in 1966) when the (better) German and Italian carbs were already available, and were in fact being used on their own nation’s competition machines. It was against those machines that bikes fitted with the Mk1 repeatedly prevailed. It’s the difference between theory and practice. No one is saying that Mk1s are 'the best', only that they are by no means the worst!

[John R]

The air slide doesn't do anything in Oz, England or probably anywhere else for that matter.