Try this:
- remove both plugs
- turn engine counter clockwise as viewed from the left side, as per the normal rotation of the engine, be careful if you use a wrench because you can hit the brush assembly when the engine snaps over
- watch for left intake valve rocker to move down, opening the valve and keep turning until the rocker rises again, closing the valve
- now put your straw down the left plug hole, same side as the PMA, of course, and turn the crank until you feel the piston rising and is at it's highest point. you can go back and forth a bit to make sure, but at this point both the intake valve and exhaust valve rockers should be loose, in other words both valves closed.
- you are at top dead center on the compression stroke for the left cylinder
- adjust the valves on that side.
now do the right side watching this time for the right intake valve to open and close and then feel for the piston to come to the top. A little harder to do but you will get it and then adjust the intake and exhaust for the right side.
- then remove the cap on the cam chain chain adjuster at the rear of the engine below the carbs and adjust it in while rotating the engine a few times until the plunger is just flush with the end of the adjuster. Tiny bit of movement is fine but the inner plunger should not extend past the adjuster.
Your done.
Good Luck.
Attached document might help. Sorry about the poor quality. PM me and I can send you a better copy that is too large to upload here.