Hello paul, this is straight out of Freds guide-
PARTS FALLING OFF
Mopeds are single cylinder engines... which means they vibrate a lot... they also have crude suspensions... which means a lot of road vibes shake everything.
So bolts can loosen up and fall out and you will actually lose parts on the road.
To stop that... put "blue Loctite" (from the Auto parts store) on ALL the bolts and nuts and screws when you are working on your moped... don't use red loctite.. (it sticks tooo well)
Losing a $35 piece of plastic because a 5 cent screw fell out... SUCKS !
to read the rest, click on Resources, then Articles, then Freds guide. It is so informative it makes me sick (just kidding Fred, we all love you for writing that article.)