RE: Magnum 120FS RPM issue
2 HP ought to pull about 9000 W/a 15 X 8. You're only making a little more than 1/2 of that according to this [link=http://personal.osi.hu/fuzesisz/strc_eng/index.htm]HP/THRUST CALCULATOR[/link].
Is it broken in? What is the valve lash? Bad fuel? Too rich on the HSN?
Something isn't right for sure.