hmmm... a jimi avatar and a link to an animation of jimi at monterey and you don't know the pentatonic scale???
pretty much every solo hendrix played is pentatonic. you might not know you know it but if you can play anything of his then you do.
that's the other thing, when it comes to improvising the less thinking you do the better you sound. there's an old blues saying
'if you're thinking you're stinking' and that most definitely applies to improvisation. i also recently read an article about how certain analytical parts of the brain shut down when a musician was really getting into their improvisation.
my best advice when it comes to improv, like any other aspect of playing music, is to just do it as much as possible. focus less on the modes and scales being played on your guitar and more on the overall sound of the music being created. another thing that helped me develop my skills and style was to play along to music that didn't already have a guitar track or wasn't rock based, like old school free jazz or electronic music.