Zenith 24T2 advice please

[David.H]

In the picture is the throttle fully closed in the picture? Did you leave the old link in place? The one at 8 o'clock to the new one's 9.
REALLY helpful, many thanks
D

[Colin Morgan]

It looks like it is closed from the position of the old link?  I don't think I ever removed it.  The fine adjustment available on the length with this set-up was used to ensure the flap fully opened and fully closed as the throttle was pressed.

Colin

[David.H]

Thanks Colin, 
I am looking at my old Chummy today, so between these pictures and that I should be able to sort something. 
Typical that the linkage is between the block & the carburettor!!
Mr S**'s well known law applies !
D

[David.H]

I got to look at the other 24T2 assembly and the operating lever was 90 degrees different. I filed new slots in my lever and it operates fine...now to see if the "new" carb works. The drain tap leaked, so needed a clean up with 1200 grade both the tap and the seat...now good. The former fuel pie was manipulated to fit, the choke is a bit of a faff & will need some creativity. I will see if it runs later today! Plating with the main jet adjuster will be interesting. I also managed to get what I hope is a 50 slow running jet from a tractor man for £4.95...delivered!

[Bob Culver]

As with many other later Zeniths the operating principle is more Solex. The air bleeds are not tiny or particulalry precise and if you know approx how long drilling is, can make, or alter with solder. The smaller the richer the mix, esp at high air flows into engine.. 150 would probably be 1.5 mm

[David.H]

Thanks for that information. All is fitted & I will see how/ if it goes tomorrow!

[Colin Morgan]

Hope you easily find the sweet spot when adjusting the main jet and it runs well.

Colin

[David.H]

Thanks for the good wishes!
Good news:
It started first time Full choke. Ignition retarded.

Not so good news- the engine does not want to slow down! It runs very fast ie as if with a significantly wide open throttle! retarding the ignition of course slows it a bit (like on a veteran!) with much popping and banging.
Throttle stop is closed.
Slow running adjustment screw makes little or no difference.
I think the throttle butterfly is opening/closing. It did before the carb went on! To be checked.
There is no "ARB" (Air Cap) which should be a 150 (1.5mm) hole, but without it there is an approx 6mm hole. This should weaken the mixture by "ventilating" (reducing the depression) in the choke tube. Some applications have no Air Cap anyway left out to achieve this. Note I do not totally understand this and am paraphrasing the Zenith manual!
The (adjustable) main jet can be moved significantly. I set it as suggested earlier in this thread. Moving it does make a bit of difference, but the engine continues to rev it's little head off!
So is it the ARB? If I cannot find a 150 ARB Until I can then I can probably make one up from a suitable thread and drill it 1.5mm.

However I am pleased with this so far! At least it doesn't pour petrol over the hot exhaust like the 22FZ....

[Bob Culver]

from the picture there seems no scope for air entry except past the butterfly. Any book which describes the Solex principle will cover the air vent. (Even Zenith carbs with a compensator jet operate largely on solex principle) Is the wiper pipe open somewhere?

[David.H]

All it was was the "new" throttle linkage was awry! it was affected by the hand throttle (which with the Advance /Retard) is not well secured at the top of the steering column and I have not been brave enough to dismantle it all. Stator tubes ( I imagine it has one?) & their fixings are something I have never come to terms with!
So with the hand throttle link disconnected , and also the throttle link and just using the butterfly away it went and I was able to set up a decent tick over. So it is a matter of getting a linkage to work properly......
Thanks for your support folks!