Timing chain diagram

Have you taken off yet? If set it to top dead center. To set the timing you should turn the number one piston to TDC, check the cam to where both valves on number one are close. The timing mark on the sprocket should now be in line with the mark on the cylinder head. Remove chain without any major disturbance to sprockets. Check number one still on TDC. Cam mark right. Fit the new chain.
After fitting turn the engine a few times by hand to make sure there is not a valve pushing/hitting against a piston. Recheck marks.

Oops. Word missing. If number one set to top dead center before removing chain.