I've never done this before but after reading a few thread I decided to check my valves for the first time and to my surprise it was much easier than I thought.
My bike is a 2005 Sp 500 HO.
I first pulled the seat and the right side panel off, and that's it! It wasn't too bad to get at.
Next I pulled the spark plug out and removed both the head cover ( 8-8mm bolts)
then the side cam cover (5-8mm bolts).
Also remove the plug in the recoil cover (14mm bolt) to see the timming marks.
Next I turned the engine over with the pull cord untill it was at TDC of the compression stroke.
The best was to tell that your at TDC of the compression stroke is to rotate the engine until the
timing marks are parallel to rocker cover gasket surface.
The cam sprocket locating pin will be facing upward directly in line with the crankshaft to camshaft center line.
Now fine adjust by looking into the timing hole in the recoil cover and line up the upside down "T" on
the flywheel into the center of the hole.
Now using a feeler gauge, slide the .006" (.15mm)blade between the top of the valve and the bottom of the adjuster and adjust accordingly
To adjust, Loosen the locknut (10mm) and check clearance with a feeler guage. Clearance should be .006" (.15mm) for both, intake and exhaust valves. Turn the adjuster with a stubby flat blade screwdriver untill the proper clearance is achieved then tighten the locknut (5.8-7.2 ft. lbs) while holding the adjuster in place with the screwdriver. Re-check the clearance with the feeler guage one last time and re-assemble the covers (72 in.lbs) and plugs.
The only thing that i noticed was that I had to clean and silicone the side cam cover other than that I found the whole process rather simple.
I'd give it a 4 out of 10 on the skill level scale.
I hope this helps!