5 Reasons Your Motorcycle is Backfiring

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Cruising down the road on your new or used motorcycle, feeling the breeze as you ride, and suddenly you hear a loud pop coming from your exhaust. What may seem like a cool sound effect at first can actually be a sign of bigger problems with your motorcycle. Cycle Trader is sharing five reasons your motorcycle could be backfiring and what you can do to resolve this problem so you can keep riding.

What is Backfiring?

Whether you’re riding a new or used street bike, cruiser, or another motorcycle, backfiring can be a common problem. Backfiring is actually a symptom of poor fueling, and at its worst, it can lead to overheating, damage to your valve train, exhaust, and muffler system, and intake problems. Backfiring results from a disproportionate mixture of air and fuel in your bike’s engine. Too little air and the unburnt fuel in your bike builds up and ignites in the pipe and muffler and pops; too little fuel in your bike and the engine struggles with full burning, which leads to overheating and auto-combustion, or what’s known as knocking.

Reasons Your Motorcycle is Backfiring

In addition to knowing motorcycle parts that most commonly need to be replaced, you may have to do further maintenance to resolve backfiring. The good news is that most motorcycles on the market today come with Engine Control Units (ECU) that use smart air, fuel, and burnt fuel sensors all over the engine. ECUs will help detect and keep the correct proportion of fuel and air in your motorcycle to prevent backfiring. Nonetheless, here are several reasons why your motorcycle could be backfiring and what you can do to fix this problem.

1. Check the Lambda Sensor

The lambda sensor sits in a constant stream of red-hot exhaust gas, typically under the engine, and often picks up road debris over time, which can cause it to fail. Get your lambda sensor tested at a local repair shop and make a replacement. If it’s blown, a new sensor should resolve this problem.

2. Look for Exhaust Leaks

Exhaust leaks can be easy to spot and fix. Run the engine, and try and get a feel for the draft of air coming out of the bike while holding up a thin piece of paper near the engine; or smell for leaks all along the plumbing. If the paper bends when held up against the draft, there’s gas blowing out. Spot exactly where the leak is located and fix it by tightening the clamp and replacing the seal. You can also take your bike to a mechanic and purchase a replacement part.

3. Look for Intake Leaks

Intake leaks can be more difficult to find, as they usually happen deep under the tank or seat. You can take off the fuel tank and see if you can find the leak. Or, you can use a can of instant start spray around the plastic intake parts while the engine is cold, then start it up, and see if the backfiring stops. If it goes away, this means you have an intake leak. Use the spray on specific areas to try and pinpoint the leak, then try a restart to see if this solves the problem. Unfortunately, to fix your intake leak you may have to find replacement gaskets and seals.

4. Injector Problems

See if your motorcycle’s injector is acting up and causing fueling problems and backfiring. Run the engine from cold for a few seconds, then check all exhaust pipe temperatures. They should all be the same; any that are usually hot or cold could signal a malfunctioning injector. Sometimes fuel lines and pumps can fail, both which cause backfiring and bad running. These can be tricky to spot, and you may need to take your bike to a mechanic.

5. ECU Programming

In some cases, especially with an imported motorcycle, the ECU could be made for a different climate and may not have the right setup for detecting the fuel and air ratio within your motorcycle. You can get a Power-Commander add-in that will resolve this with your bike, or you can take your motorcycle to a local dealer and get the ECU reprogrammed. Both will prevent backfiring.

Backfiring is a common motorcycle problem that can lead to serious damage. In addition to keeping up with routine motorcycle maintenance, be sure to stay on top of this problem. If you’re looking for your next new or used motorcycle, be sure to visit CycleTrader.com for all the nationwide listings.