I just sold a 2000 lt80 to a private party. The bike ran great when I sold it and I have always taken great care of it. I sold it "as is", but now 3 days after I sold it, it won't start. The buyer lives far from me and I really have no idea if it's from their abuse or if the quad was damaged before the sale.
The story is that the bike was running just fine, maybe a little rich. He says it suddenly got a little louder and shut off, and now won't start. It cranks over just fine, has fuel and spark, but won't start. Sounds to me like it's flooded or has a bad tank of fuel.
If anyone could give me some advice I would really appreciate it, it's stressing me out and I don't want to be one of those guys who just says, "Oh well, AS IS"

 

Check compression 100 - 120 psi
Mabie a reed broke if it's after market.
For all you know they could have left a rag in the air box.
If you want to be the good guy, tell them to bring it back and you'll fix it.
Sorry, no easy answer for you. Good luck.

 

Possibilitys::
carb needs cleaned (I always start there)
spark plug cap blew off (they suck, use duct tape)
spark plug itself came out (rare)
head gasket blew (good chance)
Let's go from there. [img]i/expressions/face-icon-small-smile.gif[/img]