Sometimes you hate them...

With the milage, it's agood bet the chain has a lot of wear..but I doubt it's enough to jump it...I would also look into the carb..many a carb has small piles of "crud" that got thru the filter and build up over time. A quick panic stop can send these floating all over, and they will get sucked into all the passages. You also could have gotten something lodged in an air bleed hole too. How much fuel was in the tank? Could have dislodged something there too...I'd replace the fuel filter, and toss a rebuild kit at the carb, and check for the jumped chain.