Amal concentric pilot jet bush

It's well documented that Amal went from a pilot jet screwed into the float chamber
To a pilot jet bush
The reason was given is the signal from the engine was too weak for a jet so far away I believe
Has anyone on here tried drilling the pilot jet bush out,and reinstating the screw in type just to see if it works?

baz said:

It's well documented that Amal went from a pilot jet screwed into the float chamber
To a pilot jet bush
The reason was given is the signal from the engine was too weak for a jet so far away I believe
Has anyone on here tried drilling the pilot jet bush out,and reinstating the screw in type just to see if it works?

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A very common mod down here. Friend has done dozens of carbs. Mostly so you could clean out the idle mixing passages properly. Not so common now the Premiers have come in.

johnm said:

A very common mod down here. Friend has done dozens of carbs. Mostly so you could clean out the idle mixing passages properly. Not so common now the Premiers have come in.

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Yep I have drilled the back of the carb and fttting a plug so I could rod the pilot bush properly
I was wondering if anyone here had direct experience of before and after drilling out the bush and adding a pilot jet into the redundant threaded hole
And if the reason that Amal give is actually correct
Or maybe just cost cutting maybe?

baz said:

Yep I have drilled the back of the carb and fttting a plug so I could rod the pilot bush properly
I was wondering if anyone here had direct experience of before and after drilling out the bush and adding a pilot jet into the redundant threaded hole
And if the reason that Amal give is actually correct
Or maybe just cost cutting maybe?

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I have just done this mod for a single carb on an Indian Velocette 500cc venom engine. it works brilliantly. we knocked the original pilot tube out.

nimrod said:

I have just done this mod for a single carb on an Indian Velocette 500cc venom engine. it works brilliantly. we knocked the original pilot tube out.

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What size pilot jet did you use?

Baz,.... it's like you read my mind. I bought the screw in pilot jets 30 years ago thinking I would do just what you are proposing. After doing as much reading as possible, instead I did what you did. I drilled out the back side of each carb so I could access the pressed in jet passage from behind it, then I threaded the hole I drilled for a set screw to seal it back up... I still have the "screw in" style jets in my carb parts bin. I believe they say "25" on them, and best as I can recall that was the proper size for my 930's..

As you said the beauty of the old style idle jet is you could remove them and clean them out. I don't know if the second part of your question is true because I never pulled the pressed in idle jet because of the modification we both did to make servicing it easier... It does make sense that the jet being closer to the pulse is better than being further away....

baz said:

What size pilot jet did you use?

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I think it was a 25, if I find it different I will let you know cheers