i just bought a 2003 sks 700. its been taken care of sorta. i just cleaned the power valves and he hasnt cleaned them for awhile but after that i took it for a ride and she kept boggin out at 60mph. so i changed spark plugs didnt do anything. now the engine revs up in the 7's and 8's doin 30mph. the clutches look like they are running correctly and it sounds to be hitting on both cylinders....any ideas of what could be wrong?