97 honda shadow 1100 backfires at low speeds?

Ive changed mainjets and balenced the carbs. Changed plugs nothing seems to work.

Check your exhaust gaskets where the pipes come out of the block. Also check the boots where the carbs mount up. If you have an air leak in either of these places it will cause the bike to pop due to it changing the air mixture in the cylinder. If this isn't the fix then there is something causing the bike to run lean.

Did you clean the carbs thoroughly when you changed the jets. Jets mean nothing if the pathways inside the carb to the venturi's are clogged.

Good Luck.