Complaint - No top end, cuts out, low end has no power below 5,000 RPM - Corrective action - New fuel pump contacts installed corrected top end speed. but the low end still bogging below 5,000 RPM. Corrective action - Removed carb assy found air valves stuck open. Cleaned carb's and air cut off valves out, re installed, adjusted mixture screws and synced. Low end power back to normal but has occasional miss at idle - Corrective action, installed new spark plugs. Bike now runs like new !!