E: Engine Comet Amal MK1 Concentric

[Tony Wilkinson]

Any side bowl type 276 or 289 carb will drip fuel if the machine is sat on it's side stand, and also if the fuel taps are leaking internally...........Disconnect the fuel pipe connection and leave a small container under the tap overnight and you will find a lot leak internally...........This is the primary cause of leaks from these carby's............No amount of replacement gaskets and sealants will stop it.

I have new fuel taps which do not leak but carb leaks as soon as fuel is turned on. Still hopefully this will be cured once I have the Concentric carb fitted.

 

[greg brillus]

The float level is most likely too high if that is the case.

 

[James B]

I made this up in order to set the float level on mine.

I think the fuel level is about right as shown in the photo, but it is difficult to find specifications for this so happy to be advised otherwise

J

 

[James B]

Note the weepage telltale down the back of the float chamber, and the throttle stop that had decided to unwind itself

 

[greg brillus]

It is generally set at the base of the mixture screw thread, this is open to opinion on account of the angle some carb's are mounted to the engine, but your method of checking works best.

 

[Tony Wilkinson]

I am happy to report that the Amal MK1 (Burlen) Concentric is now fitted. I had to wait for a new throttle cable with a longer inner to get the bike running again. From first startup the bike sounded better and ticks over like a Swiss watch.
The seller said this carb was all set up for a standard Comet and he was not wrong. It runs cleanly throughout the rev range, starts easily and importantly does not leak, happy days.

 

[Martyn Goodwin]

I am happy to report that the Amal MK1 (Burlen) Concentric is now fitted. I had to wait for a new throttle cable with a longer inner to get the bike running again. From first startup the bike sounded better and ticks over like a Swiss watch.
The seller said this carb was all set up for a standard Comet and he was not wrong. It runs cleanly throughout the rev range, starts easily and importantly does not leak, happy days.

Hi Tony,

That was my understanding when I purchased and fitted a 30mm Mk1 to my comet. It came fitted with a 190 main. 3 pistons later I am now on a 240 main - it is amazing how well these bike run lean - till the piston fails!

Do you know how the carb is set up? What main, what needle jet, needle etc. ? Care to share?

Martyn

 

[Mike 40M]

When I bought my Comet it was fitted with a 930(?) Concentric. The seller mentioned that the idle jet has been drilled a bit. As it runs, idles and starts well, I haven't bothered to examine it closer.

 

[Bill Thomas]

I have only recently acquired my 1950 Comet and am generally pleased with it. I have had a number of issues and am slowly through them. The mag was weak and would die when the engine got hot. I have since replaced with electronic coil ignition which seems to work very well.
The bike was fitted with it's original 229 carburettor but despite rebuilding still suffered from flooding and constant leaking. I have recently purchased a used but excellent condition Amal (Burlen) MK1 carburettor 928/L301. It is said to be set up for a Comet and had indeed been fitted to one as it has the correct inlet stub.
It has a 200 main jet and before I install it, I would like some advice please. does this seem correct ?

The Britbike web site says 28mm 180, and 30mm 200 Main jet as a start setting, With standard Silencer and air cleaner !!!!?. As Martyn says, Worth going up a bit for safety, And with the petrol as it is ?.
Also if you have a straight through silencer, It will need a bigger main jet. Cheers Bill.

 

[Tony Wilkinson]

Hi Tony,

That was my understanding when I purchased and fitted a 30mm Mk1 to my comet. It came fitted with a 190 main. 3 pistons later I am now on a 240 main - it is amazing how well these bike run lean - till the piston fails!

Do you know how the carb is set up? What main, what needle jet, needle etc. ? Care to share?

Martyn

Hi, sorry for the late reply, I have been away.
It is a 928 L301 carb, 200 main jet, 106 needle jet and a no 3 cutaway slide, running with an Amal no 900 bell mouth, sorry can't remember what needle but clip in middle groove.