Hey,

I've just been through this exercise, with my L20b and flat top SU's.

This website has a lot of info and a excel file you can download to compare different jets.

Hitachi SU website

How do you know it's lean high in the rev range?
Alls SU's have stamped numbers on the needles, check what your needle is then find a comparison needle with the excel as an example I had M66 needles but I inceased the motor from 1800cc to 2000cc so I needed a needle richer across the whole rev range, so I orderd a pair of SU needle very simular to the M87 nissan needle and they work a treat. cost about $30 for a pair of needles.

As a first test try sliding the needles up all the way in the mounts this will increase the fuel across the rev range, but it should help you know if you need different needles or not.


Hitachi SUs and British SUs about the only part that is the same is the needles.

cheers