I need to re jet my nikki for a semi bridge. It's running 15:1 on idle aeround 2k rpm and maybe a little lean on power. Will the mazdatrix jets work in the slow speed position. If so how big should I go compared to the stock ones.

 

As I had a spare Nikki to play with, I just drilled jets until I was happy with the AFR.
I machined the primaries ventury to 24mm, and so far my stockport is happy with 110 on the primary fuel jets (from 92).
I dod not touch the idel jets, but I had to play with idle speed screw and richness screw.

We'll see when the halfbridge is closed and in the car again.

 

You need to go as large as you can but at some point you will need to modify the air bleeds. When I did my hogged out nikki I was able to get the nikki tuned without going that far but it was a stock port 12A. @jeff13b would have more knowledge about nikki jetting for various porting.

 

Have modified Venturis if interested. These are stock size worked good for my street port 13b. Can go bigger if u want. $20 plus shipping.