Having adjusted many types of 4 stroke engines I have found the sure fire way to get the valves in the correct position for checking is;
1 - remove the spark plugs, but first blow all the debris away from around the spark plugs so it doesn't fall down into your engine. By the way do the clean up before removing the valve cover or at least re-install it to prevent dirt from getting into the valve train. Cleanliness is next to godliness.
2 - rotate the engine in the right direction is a must. Not sure, put transmission in 2nd gear and bump the rear wheel in the correct direction and see which way the crank turns.
3 - now rotate the crank until the intake valve, for which ever cylinder you want to start on, moves down and then back up. stop.
4 - place a straw, or something that size down the spark plug hole and now continue turning over the engine while gently holding onto the straw and guiding it upward. Anything bigger and you could jam a valve and bend something. Be careful and you will do just fine.
5 - your piston is coming up to TDC and when you feel it has reached the highest point you are there. I don't like to rotate in the wrong direction, so if it goes slightly past TDC you are still okay as you are on the compression stroke and the valves are closed tight for sure. Not comfortable with that, then go to step 3 and repeat and watch more closely for TDC the next time.
6 - adjust the valves for that cylinder, both intake and exhaust. They should both be loose and adjustable. If not go to step 3 and repeat.
7 - one cylinder done, go to the next cylinder and repeat steps 3 - 6.
Job done!
Many bikes require this method simply because it is to much work to get to the timing marks and or too difficult/awkward to see them.
