Is the engine popping, or is the chain popping off? Im guessing the chain since your talking about the tension, usually if it pops off it means it and the sprockets are worn out, even though the chain can be tight on the tensioner. Chain and sprockets should be fairly easy to replace, just grab a manual and thatll help explain how to do it.
-Nick
1988 Chevy Silverado 5.9L Cummins : 1986 ATC250R : 2012 Polaris RZR 570 :
98% of Americans say 'OH $#!T!!' before going into a ditch on an icy road. The other 2% are Alaskans, and they say 'Here, hold my beer and watch this!!'