Now here you need a 5mm drill bit and very carefull hands. I wont put pics up for this as I dont think it will help. Look down the secondary passage from the top and then look through it from the bottom and you will see half way up there is a big turn creating a restriction. What you have to do is drill from the top and bottom carefully to remove the restriction But if you drill to deep either up or down you will put a hole out through the side of the carb. If you mark the drill bit with a texta 1/4 inch from the tip and don't go past this point up or down and then go little bit further at a time looking through the passage till the restriction is removed. First pic is a undrilled one and the second pic is a drilled passage and you can see the difference.
