To get the valvecover off and on, it´s nessesary to remove the ignitioncoil/CDI.unit and cableconnectors. To do that it´s okay to remove the bracket wich holds the whole shebang. Hold it up with a rubberband or the likes.
Behind the valvecover is an bracket which holds the cylinderhead. Only the right triangle part can be removed (do that !)
All this, just gives enough space to maneuvre the Valvecover on and off. Still be careful in handling the cover and gasket..
To check and adjust camchain tension, loosen th two M6 Bolts (just loosen them don´t screw them out !) behind the cylinder-head and cylinder. Than turn the crankshaft counterclockwise. Holding the crankshaft under light tension, the M6 Bolts can be tightened again The hexbolts are M10 for the spanner-width.
Camchain-tension should be correct know and further manual tensioning isn´t nessesary.
good luck !