I got two B's second semester junior year of high school. How much does that ruin my chances of getting into a good school?

Yes, it’s the UC weighted capped. As stated by another poster, the Bs could raise questions about your performance in college. You could ask your counselor if you should address it on your application. In my opinion your test scores and recommendations will help for your private options, but grades are king, and especially at the UCs.