Updraught Zenith FZ /FZB jets.

[Ray White]

I am switching from a Mazak FZB to a bronze FZ  carburettor and I have noticed there are two different size jets. 

The FZB main is 70 and the slow running 75. 

The FZ   main is 75 and the slow running 70.

Could someone please advise me which is correct?
  
Thanks,

Ray.

[Steve Jones]

Don't know if it's correct but the FZ on my SWB Salooon has 70 Main and a 75 Compensating jets. Goes very well.

Steve

[Ray White]

Don't know if it's correct but the FZ on my SWB Salooon has 70 Main and a 75 Compensating jets. Goes very well.

Steve

Thanks Steve.  That's the combination I have always had with the FZB on my car. The FZ I have is an unknown quantity so if there are no other replies convincing me to the contrary I will swap the jets over.

[Mike Costigan]

I don't recall the values, but I have always found the same combination on FZ and FZB

[Ray White]

I don't recall the values, but I have always found the same combination on FZ and FZB

Thanks Mike.  I repaired the FZB  many years ago but that repair has failed (not for the first time) so given that I have other carbs to choose from - including an FZ with very much less wear - I shall make the change.  I don't like anything that strays from the original where 'Trundles' is concerned but I think the time has come so what I am doing is taking all the best bits off of the poor old Mazak carb and fitting them to the bronze one.  

It cleans up nicely as well!

Ray.

[Howard Wright]

Hi Ray

In the three or so FZ carbs I have played with all have a larger slow running jet than main jet.  

Cheers

Howard

[Ray White]

Thank you Howard.  I have a copy of the Zenith instruction booklet but I can find no information in there.  I think it is great to have such a wealth of knowledge here on our forum.

Thank you,

Ray.