It seems that everytime I drive my st 15, I have to reset the high speed needle settings. If i dont, the mixture will become too rich and I wont be able to get past half throttle. Is this normal, and how can I fix it??

Watch the needle with the motor running, is the needle vibrating a lot? You could mark the needle and the side to see how much it is actually moving.

ya thats normal u should reset all needles for that day like on a cold day it wont act the same on that setting thn it would on a hot day

No, that's not normal. Unless there have been drastic changes in weather conditions you're settings shouldn't be off so much that you can't get past half throttle. Most of the time you should only have to tweak your tuning for the exact conditions of the moment.

I agree that it's probably vibrating out. I don't really know of a solution either.. I'm not sure that you'd want to threadlock it, since you're going to have to adjust it.

use plumming tape the stuff in the whight and blue contaner u know plulling tape just put it on treads i do it to keep diff from comeing lose

are you talking about teflon tape?

ya that it y