Why Do Flames Come Out of Motorcycle Exhaust?

Many people do not consider the maintenance of motorcycles as an essential task that needs to be done regularly; otherwise, it can cause flames from the motorcycle exhaust and poor functioning of the engine and internal components.

Why Do Flames Come Out of Motorcycle Exhaust? Flames come out of the motorcycle exhaust due to loose exhaust headers and the masking of spark plugs. Moreover, poor mixing of the fuel and air can also cause the burning of the unburnt particles in the exhaust pipe. Furthermore, poor electronic timing, short pipes, and jets clogging are responsible for backfiring in the exhaust pipes.

It indicates a problem with internal components that do not allow fuel to combust inside the chamber, and fuel particles ignite upon reaching the exhaust pipe.

What are the reasons for flames coming out of the motorcycle exhaust?

Most probably, you have seen motorcycles releasing high flames from the exhaust pipe for many reasons, like there can be an issue with a carburetor, spark plugs, and jets.

Loose exhaust pipe

A metal pipe or an exhaust header is connected to the motorcycle’s engine and throws burnt gases out of it. In addition, it is usually tightly fixed with engine components to avoid gas leakage.

It can be disconnected for cleaning and maintenance purposes and leaves a chance of inaccurate fitting while fixing it back into its position.

Likewise, excessive vibration of the motorcycle when it runs on a rough road can loosen the nuts over time.

The hot fumes from the engine entering the pipe can also make their way through a hole and cause backfiring, producing higher flames out of the pipe region.

It is better to tighten up the screws of headers connecting the exhaust header to a cylinder head to avoid air leakage through its sides.

Furthermore, the bolts and nuts that need to be welded or replaced can be broken. Avoid riding on a vehicle having loose pipes and check the connections regularly to ensure safety.

Masking of spark plugs

Spark plugs control the ignition of the fuel-air mixture when it gets compressed in the ignition chamber.

The deposits on the spark plugs can affect their performance as they cannot produce a spark. Uneven ignition occurs due to the masking of these plugs with deposits and can cause a backfire.

In addition, the unburnt fuel leaves the chamber and ignites or causes detonation when it enters a hot exhaust pipe that can produce flames.

It is considered ideal for checking the condition of spark plugs every 3500 to 5000 miles. In addition, replace the faulty plugs after checking the gap.

Furthermore, this gap needs to be almost 0.03 to 0.04 inches, and you have to replace the spark plugs if it is lower than this range.

Incorrect mixing of fuel and air

Disturbance in the air and fuel mixture can also affect the normal functioning of the engine as some fuel particles remain unburnt when there is less quantity of air in comparison.

These unburnt fuel particles can ignite when they touch a hot surface of the exhaust pipe and generate high flames from the motorcycle exhaust.

In the same way, a small amount of fuel in excessive air can also cause problematic situations as it keeps the engine in a lean condition.

The excess air suppresses the combustion process and leaves the combustion chamber without proper combustion.

This mixture had too little fuel and could get burned in the exhaust pipe due to the high temperature of metal pipes and ignites that can cause a loud sound.

It is essential to smell the fuel by standing close to a running engine, as there will be a strong odor of fuel when there is too much fuel in the combustion chamber.

In addition, you can check the fuel economy, which can give an idea about the excessive consumption of fuel that is being added into the combustion chamber.

Furthermore, you can quickly identify the problems in the inlet valves if more fuel is burning in the chamber than required.

Clogging in jets

A few primary components in the motorcycle are responsible for engine running, including the main jet that controls the exact amount of fuel required for burning when throttle power is 50 to 100%.

The pilot jets control the fuel amount during idling conditions, and the needle jet determines its consumption when the throttle power is around 15 to 50%.

Additionally, the jet needle controls fuel consumption when the throttle power is between 20 and 80% and is a part of the carburetor.

However, there is a possibility of clogging of jets due to dirt that allows less fuel to enter the carburetor.

Poor cleaning and lesser maintenance can lead to blockage of these jets and is responsible for producing lean mixtures of fuel and air and causing backfiring.

So, it is considered better to clean the jets regularly and prevent the accumulation of dirt within jets that will not affect the air-fuel ratio.

Furthermore, you can use a carburetor cleaner and clean every component for quick and easy flow. It can help reduce the risk of flames in the exhaust pipe and keep your vehicle safe.

Short exhaust pipes

Small exhaust pipes can be responsible for banging and loud noise due to the production of flames in the pipes. Therefore, it is considered better to keep their size more than 12 inches long.

The short pipes can give a desirable look to pipes, but they are usually responsible for loud noise as they do not contain baffles that work like mufflers and reduce noise.

Therefore, it is better to have longer pipes having removable baffles that can efficiently convert the turbulent flow of burnt gases into a laminar flow.

Many states have introduced laws about the design of vehicles that guide you about the ideal size of exhaust pipes.

Additionally, the short pipes can give you short-term benefits in the form of performance but can also be associated with backfiring issues.

Incorrect electronic timing

Some handy tools can help determine the reasons for backfiring in time, and electronic timing has made the life of motorcyclists easier.

It keeps a strict check on a few parts of the vehicle and gives you information about the actual culprit responsible for backfiring.

Moreover, it is considered electromagnetic triggering when the voltage signal is sent to the spark plugs responsible for producing a spark and burning the fuel.

Timing-related issues in the electronically controlled vehicle can cause mechanical problems like the poor running of the engine and smashing of the piston on the valves, which can cause a backfire.

In addition, it is better to set the timer manually according to the instructions given in the manual. Every motorcycle has a different manual and setting, so consider it according to the model.

You have to find certain marks inside the cover of the crankcase and line them up, followed by setting points at a specific distance.

Furthermore, it decreases the chances of seeing the flames coming out of the motorcycle and producing a loud noise.

Is backfiring bad for motorcycle engines?

Backfiring in the motorcycle can affect the engine performance and the vehicle’s exhaust system.

In addition, the inlet valves and pipes can also get damaged and do not allow the motorcycle to make enough power.

Furthermore, flames from the motorcycle exhaust increase the overall consumption of fuel and increase costs. Finally, it can be bad for an engine as the unburnt fuel causes detonation at an inaccurate time.

It causes overheating of the engine, and you have to face low fuel mileage, and motorcycles consume more gas, which can increase the overall fuel cost.

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