I have a 2007 800 sportsman. I am not getting any oil to the top end of the motor. I have a 6mm camera lens and I can see the oil pump impeller spinning through the lifter journal but it is not sending oil to the lifters.

 

First thing to check is if it has an oil pressure reading. Remove the blind plug from the left side of the engine. Install a 1/8 npt adapter and oil pressure gauge. Crank the engine,warm to operating temperature. At 5500 rpm oil pressure should be between 35-39 psi. Plus are you using the correct oil filter for the 800? Oil from the pump is pumped through the filter then to the main oil galley. From there to the lifters. The filter has a relief valve that opens in case of filter blockage bypassing the filter media. Plus there is an oil pressure relief bolt on the top engine case by the filter. It's not normally removed,but you can remove it(engine off!) and there is a spring and a dowel pin under it. Make sure the opening is clean,you can use compressed air. Reassemble making sure the dowel's chamfered end goes first.

 

I will check it out first thing in the morning. I am thankful that even retired you still have enough interest in helping others.