Runs rough after valve adjustment

I have a 1984 Honda TRX 200. It was running fine until I decided to adjust the valves on it because it hadn't been done in forever. I consulted the owner's manual and followed the valve adjustment procedures step for step. I aligned the two timing marks to make sure that the engine was at the top of the compression stroke. Once I had the marks aligned, I then wiggled the rocker arms by hand and they were loose, which would mean that the engine was indeed at the top of the compression stroke. I then adjusted both the intake and exhaust valves to the specs recommended by the manual, which was .05mm(.002in). After I put the quad back together, it was difficult to crank. I did eventually get it cranked and it idled fine. It also runs fine at lower rpms, but at upper rpms it loses power and runs extremely rough! It spits a lot of white smoke out of the tailpipe when it is running. Also, the quad has a compression release lever, which is supposed to make it easier to pull crank. After the valve adjustment the compression release lever no longer works. The lever won't stick at the top like it is supposed to. Does anyone have any idea what could be wrong with it? I am out of ideas. Any help will be greatly appreciated! Thanks.