My Suzuki Savage 650 backfires when I cut the

Hi and welcome to FixYa,

Sounds like a very lean mix; confirm by checking the sparkplug tips. If the burn is very light brown to almost whitish, then it would be lean - too much air, too little fuel. Check for an air leak in the air filter box/enclosure. This would also happen if the air filter has been replaced with an aftermarket free breather (like K & Ns) or the exhaust has been replaced and no jettings done.

Postback results of initial checks.

Good luck and thank you for asking FixYa.