savage is backfiring when engine is turned off

just bought an 04 savage 650, have put on just 250 miles on it, all stock, runs great, does not have the decelertion popping, but it does have the problem of backfiring/coughing/puffing, (chose one) when you turn off the engine, it does it with the gas lid on or off, and it doesnt matter if you use the key or the kill button, is this normal for a savage, will it hurt the engine, can rejetting help, if so would it be the needle clip position or main jet, thought i would ask before putting it in the shop, two weeks after i got it....

thanks in advance
(yes, i tried a search but was not very good at it, this is my first post, so be kind)))