Amal Concentric spray tube replacement DIY

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p400

p400

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I have a pair of 930 Amal Concentric with standard spray tubes and I want to convert them to the 850 notched spray tubes.

Certainly "knock the old out and knock the new in" is a basic instruction, but I need help from someone who is successfully doing this on a regular basis.

Should the Amal carb body be heated up ? or does it matter?

Any special tool needed to knock out or install a new spray tube?

Shown below I am going from "4 stroke" to "Norton"

Amal Concentric spray tube replacement DIY
 
They are easy enough to change just drift them out
A bit of heat will always help but depending on what you are doing and the spec of your bike just try the 2 ring needles first
Were the stepped spray tube/4 ring needles used in 930 concentrics?
I have only seen them in 932s
 
baz said:
Were the stepped spray tube/4 ring needles used in 930 concentrics?
I have only seen them in 932s
Click to expand...

I'm fairly sure the answer is no.

Not sure what will happen with the Norton spray tube and non-Norton needle. If I were going to change the spray tubes (I wouldn't), I would get a pair of the Norton needles, Part # 928/104

See the details pages linked from the last table here: http://gregmarsh.com/MC/CommandoID.aspx
 
baz said:
They are easy enough to change just drift them out
A bit of heat will always help but depending on what you are doing and the spec of your bike just try the 2 ring needles first
Were the stepped spray tube/4 ring needles used in 930 concentrics?
I have only seen them in 932s
Click to expand...

The stepped version was done for the MKIII to address a hesitation problem with the restrictive intake/exhaust as I recall. Would've been on 32 mm carbs.
 
maylar said:
The stepped version was done for the MKIII to address a hesitation problem with the restrictive intake/exhaust as I recall. Would've been on 32 mm carbs.
Click to expand...

The stepped 928/107 spray tubes and 928/104 4 ID ring needles were standard for all 850 carbs.
 
If you have access to a lathe, turn a two diameter drift. The small dia. should be a couple of thou. down on the bore size of the bush, & the large dia. a couple of thou. down on the o/d of the bush. The tap out easily & are just as easy to replace. Without a proper drift you will probably damage the new bush.


Martyn.
 
Warm the carb body with a heat gun, hot water, or a hair dryer. Use a SOFT (plastic or wood) dowel, rod, pencil to gently push them out.
 
Just tap them out, unless corroded it is easy. I put the 2 stroke spray tubes in, had to adjust needle height. I don’t know why I did it, just thought it a good idea. The bike runs good.
Tap them back in and getting aligned is probably the hardest part.
 
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