Don't break those mixture screws!!

[pac00t]

i'm just putting out another caution after having inherited broken mixture screws... CAUTION!! On my carburators (79SF) you CANNOT feel the needles seat in due to the spring pressure. You will break the tips off before you know they have reached the bottom. I took the springs off, lightly seated the needles, then did my best by sight (micrometer?) to get the needles about that level with the springs in place. Then when you go to tune, know that you only have one turn worth of tightening left.

[newmaac]

The trick (I think) is to use the right screw driver.
The first time that I touched the mixture screws, it was with a long, skinny screw driver. I barely fit down into the bore, but had a good sized handle.
With a lfair amount of leverage, I found that I had siezed-up one of the screws before I realized that I had bottomed-out.

Now I use a little tiny handled screw driver that I have ground the tip to perfectly fit the screw head.
If you can only use the pad of your index finger and thumb, you are not likely to be breaking ANYTHING. I don't care if you drag your knuckles or not. )