It's the little things

I have crawled around these Amals inside and out, or so I thought. Sleeved, new floats, new needles and jets new every damn thing. The ignition is dialed in.
And the left side still is running rich...WTF!

I am sitting on my short stool staring at the left carb thinking what else could it be. As I continue to stare I spot a black fleck on the air adjustment screw. I wipe my finger on it and its a tiny piece of rubber.
Huh. Where did that come from...on goes the light bulb.
I unscrew the air adjustment screw and take a look at that tiny little O ring. Its got a big hack in it.
Its not sealing.
I put in a new air adjustment screw with a new O ring and guess what?

The world is right again.

Feels good when things go right!
I've got an old three-edge awl that I use to put a bevel on the inside edge of those adjuster holes to help ease in the rubber o-rings.

A little smear of dielectric grease helps, too.

Yep, the tiny o-rings can harden and crack, almost invisibly, and baffle your brains out...

That’s a good find, glad you’re sorted.

As mentioned above, silicone grease is a great help on these, prevents damage when installing, delays binding / cracking etc.

Just one small point, a damaged O ring here will allow in more air, thus causing weakness, not richness.