my father and I have just replaced the piston, rings, jug, and head and now the bike wont start does anyone know where the timing should be??? or can someone scan the section in a book plzzzzz???????

 

Piston at TDC and align the mark on the cam gear with the notch on the head.
If the cam gear was removed from the camshaft at any point, verify that the cam lobes are NOT contacting the rockers when the mark is aligned with the head. If they are, turn the cam gear a full 360 and rebolt.