2006 VECTOR WON'T REV PAST 7000 RPM

[blue rider]

Bought a 2006 vector and it won't rev past 7000 rpm. Cleaned the carbs, clutches and everything is fine. What is the device on the side frame with the hoses going into the oil tank and air box? The carbs have butterflies and slides. The slides are connected to the throttle cable but how do the slides operate? Thanks for any help provided.