Amal needle position number

Hi

When people quote Amal needle position 1, 2 or 3 which numbers
refer to top, middle or bottom groove?

Thanks

My understanding is that the top groove is always number 1 on Amal’s.

I’m even more sure that number 2 is always the middle on a 3 groove needle

Hi Fast Eddie
I was fairly sure the middle was number 2
Perhaps strange that the recommendation for 850 MK1 with straight through and ham can air filter is Groove 1
(leaner) but that for 850 with black plastic air box is number 2 (richer) with either pea-shooters or black cap silencers?
As I thought the perceived wisdom was that the black box was more restrictive than the ham-can filter?

Staytite said:

Hi Fast Eddie
I was fairly sure the middle was number 2
Perhaps strange that the recommendation for 850 MK1 with straight through and ham can air filter is Groove 1
(leaner) but that for 850 with black plastic air box is number 2 (richer) with either pea-shooters or black cap silencers?
As I thought the perceived wisdom was that the black box was more restrictive than the ham-can filter?

Click to expand...

You probably think that if you improve gas speed through the motor you will need more fuel? And you probably also think more fuel in the combustion chamber = more power.

To a point this may be true, but it is never as simple as that is it?, and is illustrated by the fact that race motors don't always have huge jets compared to road motors.

Extra gas speed through the inlets improves the 'sucking' of fuel through the same size carb jets, thereby delivering......more fuel.....through faster fuel flow. (and probably better atomisation as well, but let's keep it simple).

The restrictive exhaust and filter can lead to reduced gas flow and less 'suck' at the jets = less fuel flow into the inlet tract = bigger jet area required to deliver sufficient fuel at the reduced flow rate!

Percieved wisdom is rarely useful, because perception very often does not tie up with fact!

Though you may have meant 'received wisdom', which is often even less useful, dependent on who you received it from!

Went to Paris yesterday so feeling philosphical!

http://amalcarb.co.uk/faqs/

"Q: Needle Clip position, top down or bottom up?


A: Something that crops up all the time is whether you count the needle clip slot from the top down or bottom up. With all Amal carburettors the clip position is top down."

Thank you Fast Eddie for the thoughts and LAB for confirming the number order.
And Steve for the perceived/received wisdom and philosophy from Paris!

I did not want to start another Amal thread: I was just toying with the idea of richening
up the needle valve to lower the potential of blueing my new shiny down pipes. The old
down pipes only lasted 31 years

As the bike runs fine with the needle in number 2 (middle) position I was reticent to fix
something which isn't broken

So I've left it on number 2 and fitted the new down pipes and it runs fine. Now just need it to
stop raining so I can terrorise some tarmac

Thank you

Blue-ing of exhaust pipes might have something to do with the process which is used to chrome plate them. Some chromed pipes seem to go blue almost immediately. I cannot imagine sacrificing performance to try to stop the pipes from going blue. Raising the needles one notch on a motor which uses petrol, makes a big difference.