[james arrington]

When I start my bike it back fires it just started today

[Fr_Chuck]

Approved and moved form forum helps

[Stratmando]

Timing can do it, any recent tune up?

[RUMPLE56]

What kind of bike, make, year, model?

[Motorcycle Mech]

Good day,

Backfiring is most often caused by a lean fuel mixture.
Your carb may have plugged jets.
Also look for any gasket leaks on the exhaust system.

[Redwoodbob]

It really depends on the type of bike you have and the context of the backfire.

Is the bike a single, twin, v-twin, in-line four? Street or dirt? Carbouration or fuel injection?

If it has carbs be sure to check fuel/air mix and that nothing is sticking. If it's a multi cylinder bike and has carbs, check balance (sync) of carbs to make sure the same amount of fuel is being delivered to each cylinder.

If it has FI, run a fuel system cleaner through a tank of gas and see how that does.

If the bike has sat for a period, especially with today's fuels that have a higher percentage of ethanol, you may need to flush the system. Be sure to add stabil to you next tank of fuel if the bike will sit for more than 2 weeks.