1990 is the year.

I thought there was a point with backing the air screw out that it should rev down again or is that wrong?

Also when setting the slide height, do you set that height with the idol adjustment on the side of the carb, or open up the throttle on the handle bars and adjust it there? Also do you measure where it's flat when looking into the carb cause the middle has the round part on the slide that goes higher?