T24 Carb problem

[AustinWood]

Mogens idea seems good. I think it's almost certain that fuel isn't getting through the main jet into the airstream.
I don't think the needle valve can have this effect.

[Chris KC]

Are you able to substitute another carb (ideally from a running vehicle) if only temporarily and see if this fixes the issue? It could potentially save a lot of faffing about.

And are you quite sure you've eliminated an air leak at the manifolds? It took me two days to find mine, during which time I'd replaced nearly everything else on the engine!

[John Mason]

This problem of yours is bugging as much it is no doubt bugging you. It appears to me it is either not enough fuel or to much air. On the point of not enough petrol is the top of the float chamber properly ventilated thus allowing the correct atmospheric pressure to press down on the fuel in the chamber and thus get the correct amount into the jets. My reasons of thinking this out is. If you are only getting a small amount of fuel then by closing the choke you only get a small amount of air (the balance between the two are correct). Push in the choke and then to much air is introduced ( all out of balance) the engine stalls.
There is a vent hole some where in the top of the float chamber casting check it is nice and clear. Looking at a a drawing of your carb it looks to be somewhere around where the needle valve screws in and exits in the hole on the top 90% to the fuel inlet I may not be quite correct on where it is the picture is not that clear.

John Mason

[David.H]

This problem of yours is bugging as much it is no doubt bugging you. It appears to me it is either not enough fuel or to much air. On the point of not enough petrol is the top of the float chamber properly ventilated thus allowing the correct atmospheric pressure to press down on the fuel in the chamber and thus get the correct amount into the jets. My reasons of thinking this out is. If you are only getting a small amount of fuel then by closing the choke you only get a small amount of air (the balance between the two are correct). Push in the choke and then to much air is introduced ( all out of balance) the engine stalls.
There is a vent hole some where in the top of the float chamber casting check it is nice and clear. Looking at a a drawing of your carb it looks to be somewhere around where the needle valve screws in and exits in the hole on the top 90% to the fuel inlet  I may not be quite correct on where it is the picture is not that clear.

John Mason

Yes, John, it vents out of the "redundant" inlet  at 90 degrees  to the actual filler....Damn it , it is clear! The correct 1.5 shut off valve has arrive & I will try & find time tomorrow to try it....it came with 3 different sealing washer thicknesses, just to make it easy!

[David.H]

One wild idea ,Take main jet out ,Refit plug over  hole .This to be sure petrol canals from float camber to nozzle are free.
Then start engine  and pull strangler and it will stall nearly immediately due to over rich mixture. If not there may be some more to blow /dig out?

Mogens

That is worth a try!
D

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Are you able to substitute another carb (ideally from a running vehicle) if only temporarily and see if this fixes the issue? It could potentially save a lot of faffing about.

And are you quite sure you've eliminated an air leak at the manifolds? It took me two days to find mine, during which time I'd replaced nearly everything else on the engine!

Unfortunately the only other carb I have is on the RK saloon (a bronze FZ) that is causing me grief with (I think) the float level!!! see another post here somewhere>
D

[David.H]

Well all the bits went into the (jewellery ultrasonic cleaner, not a lot came out, very fine dust mostly.
put it back together wit the correct 1.5 float needle valve and away it went!started on full "strangler" (choke!) & quickly I was able to release the chain & reduce the need to strangle the engine & it ran smoothly. I need to adjust the slow running & throttle stop, but A RESULT!
Thanks for all your advice....unfortunately as I did two steps at once I don't really know if it was dirt or valve wot done it, but I incline towards float valve.
Now to sort the wiring...a mix of 1927/1931 components.
David

[John Mason]

Nice to know have it sorted David.