Motorcycle Repair: Backfiring, honda crf 450, fuel air mixture

Question
Hi i have an 05 honda crf 450 and i havent really rode it since feb or april of this year but i have been starting it between then up until now to just keep it from sitting to long anyways this last time i started it it started backfiring on the deceleration only and i changed the plug and the air filter is clean so if you could help me out i would appreciate it thanks

Answer
Donny,
fuel can go bad within a couple of months,
have you tried running some fresh fuel
through it? Backfiring is usually caused
by a lean fuel/air mixture. This can happen when
any changes are made to the intake, fuel system,
or exhaust system.  Sometimes the changes are
deliberate like an aftermarket pipe or carbs.
Sometimes the change is a result of  wear and tear,
air filter problems, air leak in the air/fuel  intake tubes,
air leaking into the exhaust header or pipe and
carb air valve gaskets or diaphragms cracking.
You can try tightening  your exhaust pipes a bit
where they enter the engine. Check for any loose
or open vacuum lines or emission hoses.