Hey. New to the site. I have a 2000 Polaris scrambler 400. Went to full throttle and stuck. The nuts on the top end came loose. Took it apart, replaced all seals. Now it starts and idles, but if throttle is applied will remain at higher rpm. Checked throttle cable and it is functioning properly. Do I still have an air leak in the lower end or are there other possible problems? Thanks in advance.

 

What nut? One one top of the carb for the throttle cable? Plus yes sounds like you still have a leak if throttle slack is ok and slide isn't sticking and works freely. Could be a split intake manifold sucking air,crank seals(especially the one behind the drive clutch) or even a head gasket,base gasket or sometimes even a leaking crank case can cause this. Best way is a leak down test or if you quick enough with some contact cleaner,spray all around the intake and base/head gasket and see if the rpms drop.