Amal main jet?

[g52ss]

Call me frugal if you must. Would like to resize the main jet of the Amal two jet carb for my WS. Understand that the change for 25:1 fuel would be to downsize the opening from standard #45 to #40. To modify the #45 jet I'd solder the old hole & redrill for the new size. Have the microdrills & experience from previous Webber work. Would someone tell me the size opening in the #40 jet?

Don

[Charles UK]

Not quite as simple as that, the 40 & 45 do not relate to the hole size directly, they stand for the number of drips per minute that they pass of a certain viscosity liqued.

All the amal jet holes are reamed, as a final sizing tool, so they have a perfect finish. So if you drill the hole exactly the same size it might well allow less fuel to pass than you would expect, due to tool marks left in the solder.

I have tried measuring the 400 series Amal carb jets with letter drills, as I almost have a full set of them between 90 & 155 but lots of them don't correspond exactly with them as the gaps between the letters, vary between 4 & 12 thousands of an inch.

So my advice to you would be to stick with the jet you've got, & try lowering the needle, until you get the plug the right colour, then file another groove in it, if you dare.

But please don't seize your motor by running it too weak.

Charles

[CatiGull]

Dont all the Amal carbs run 25;1 out of the box??

[John@sos]

The Amal 2 Jet needs the 40 size main jet to run on 25:1, simple as that, they are just £6.50 plus postage.

There is no other adjusdtment on a Amal 2 Jet.

The Villiers has a needle you can change or tinker with, new needle just £6.00 plus post. See the FAQ pages for much more.

And yes the Amal 400 series are all on 25:1 as is the Bing.!

hope that helps clarify matters,

Regards,
John
SOS

[CatiGull]

Thanks john, as always. Happy Spring. Listen for the bbzzz of my Forty Plus from across the Atlantic this weekend...it will be Abigail and me going up the Hudson...