Today while riding pretty rough on my little 110 the chain started off and I just kept putting it back on until it popped off the front sprocket so I pushed it back to the main trail and took off the cover and the sprocket was very loose. I have no clue at all how to tighten it.

 

Does it have 2 bolts and a retainer on top of the sprocket? If so you can see if the retainer is bent and check for excessive wear. Check you rear sprocket alingnment. (does that make sense?)

 

The front sprocket wiggles a little but not too much. The chain tensioners were cross-threaded, stripped, and just plain worn so I ordered new ones. That might help