the assembly of your engine will actually be better than new, most honda mechanics are trained in assembly of honda products, more so than the bozo's they have working on the assembly lines, the quality of honda products has dropped off a lot since they decided to have them assembled in the states[img]i/expressions/face-icon-small-disgusted.gif[/img]

 

Lesson learned make sure your quad is right before you ride it. You are lucky they didn't try blaming your brother for overtightening the chain. The mistake of overtightening a chain can be costly as you have learned. Personally, other than my own mechanic or my dad I don't really trust any one else to work on my quad, and I always double check. You know better safe than sorry!

To me your course of action is to be freaking greatful you bought a new quad from a reputable dealer than from private sale cause right now that torn up case would be your baby!