Remove jet holder through drain plug?

[maylar]

If one was to replace the Amal needle jet, can the jet holder be removed through the drain plug or does the bowl have to be dropped?

 

[Triton Thrasher]

Not through the bung hole on a Mk1 Concentric. You have to take the bowl off.

 

[lazyeye6]

I beg your pardon. I have removed and replaced the needle jet holder with the needle jet from the drain plug without
removing the float bowl. Did it with a standard socket wrench.

 

[gortnipper]

You can the main jet, but not the needle jet which sits above it. The hex is too large for the drain hole.

 

[maylar]

Anybody know the hex size of the jet holder?

 

[MexicoMike]

At least one size larger than the drain hole!

As GortN said, you can't remove the needle jet with the float bowl in place, only the main jet...and only if you didn't tighten the main too much where the needle jet holder unscrews instead of the main jet!

 

[gortnipper]

IIRC, the jet holder is 1/4W.

Correction, I think now it is not 3/16W since this article shows using a 13mm wrench, and 1/4W is 13.34

https://www.motorcycleclassics.com/mc-how-to/amal-concentric-carburetor-overhaul

 

[Fast Eddie]

...and if you didn't tighten the main too much where the needle jet holder unscrews instead of the main jet!

Ha! Been there / done that !!

 

[ELLIS]

Try using a box spanner, as i have removed the needle jet using one on my premiers.

ELLIS

 

[Fast Eddie]

It’s not got anything to do with the type of spanner / wrench / socket used... the jet holder itself will not fit through the drain hole. And unless the jet holder is removed, access to the needle jet is impossible.

I checked it out just now to make sure I’m not going crazy (see pics below).

Unless there there are different sized jet holders..?

 

[baz]

A bit of subject really,but in a similar vane
"But I did hear of a gynecologist who took his work so seriously he papered his hall through his letter box!!!"
It's really not that much work to pop a float chamber off an Amal carb
And you can save a whole float bowl of fuel if you are careful

 

[Triton Thrasher]

You can do it on a Mk1.5 though.

Or maybe you can’t! See below.

 

[baz]

You can do it on a Mk1.5 though.

Didn't know that
Maybe you can with a MK2 Amal aswell I'm sure they had a large float chamber drain screw?

 

[Fast Eddie]

You can do it on a Mk1.5 though.

The plot thickens...

It’s correct that the mk1.5 has a bigger float bowl plug (same thread size as a mk11). But it’s still not quite big enough for the jet holder to pass through (according to my parts stock).

it’s very close though, a smaller one would fit through, which has me wondering if they made a smaller one at some point (can’t see such a thing on Burlens web site though)?

See mk1 and mk1.5 float bowls and plugs below and the jet holder in the mk1.5 plug hole...

 

[Triton Thrasher]

It’s years ago, but I thought I had got it out through the hole on the 1.5s. Maybe not, then!

 

[Fast Eddie]

Unless it had a smaller jet holder... that’s what I’m now wondering... it would make perfect sense to have done so... but there’s sense, and theres Amal sense...

 

[baz]

Unless it had a smaller jet holder... that’s what I’m now wondering... it would make perfect sense to have done so... but there’s sense, and theres Amal sense...

Don't think I've seen one with a smaller hex?
I know the two stroke adapter is shorter

 

[maylar]

Well, it doesn't matter to me other than it would avoid stressing some gaskets if I didn't have to drop the bowls. The good news is that it'll give me the opportunity to clean the idle passages before firing up next spring.

A related question though, is that of the life expectancy of a needle jet. I have maybe 10000 miles on these carbs and the engine runs fine, but most of my riding is on the slide cutaway and needle jet so I'm wondering if I should replace them as a matter of principle. I don't have pin gauges that small to check for wear.

 

[baz]

Well, it doesn't matter to me other than it would avoid stressing some gaskets if I didn't have to drop the bowls. The good news is that it'll give me the opportunity to clean the idle passages before firing up next spring.

A related question though, is that of the life expectancy of a needle jet. I have maybe 10000 miles on these carbs and the engine runs fine, but most of my riding is on the slide cutaway and needle jet so I'm wondering if I should replace them as a matter of principle. I don't have pin gauges that small to check for wear.

You'd do better just changing them to be honest

 

[Fast Eddie]

At 10,000 miles I would personally definitely change the needle jets AND the needles (zero point in replacing one without the other, it’d be like putting a worn piston in a new bore).