When riding the motorcycle or even at idle, you suddenly experience your motorcycle stutter and hesitate when you roll the throttle like there is a drop in power output and the motorcycle is going to stall. The issue/problem you are facing is called engine sputtering.
Motorcycle sputtering is commonly caused by a faulty ignition system or fuel system where the motorcycle engine is not able to achieve full ideal combustion. The uneven supply of air/fuel ratio to the combustion chamber or a weak spark ignition will produce inefficient power which will result in the motorcycle sputtering or stalling.
In this article, we will understand what engine sputtering is in the motorcycle and what it means, and the damages it can do to the motorcycle. We also look into the causes of motorcycle sputtering and how to fix it and stop your motorcycle from sputtering.
With a solid maintenance routine, you will be able to prevent motorcycle sputtering.
And the knowledge of identifying symptoms of engine sputter in this article while acceleration (high rpm), idling (low rpm), under load, or at open/close throttle whether it be a 2-stroke motorcycle or a 4-stroke you will be able to understand and tackle this engine/motorcycle sputtering problem with ease.
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What Is Motorcycle Sputtering?
Motorcycle sputtering is a situation where the engine is not achieving its full combustion and normal power output. The motorcycle will spontaneously lose its power in a frequent manner with a delayed throttle response which can be a similar feeling to a hesitant or stalling motorcycle.
This will result in poor performance and the bike will stutter/sputter under acceleration (rolling the throttle) or even during idle.
A sputtering motorcycle will make a series of soft explosive sounds at a fast pace which is different from a normal idling or revving sound of the motorcycle.
What Does It Mean When A Motorcycle Sputters?
Motorcycle sputters/sputtering simply means that the motorcycle is losing its power in a frequent erratic manner during idling or accelerating. This is caused due to a malfunctioning ignition system (i.e. spark plugs/wires, ignition coil, ignition switch) or the fuel system (i.e. carburetor, fuel injectors, fuel lines/pump).
This happens because the air/fuel mixture is not burning properly and not having ideal full combustion.
Engine sputtering is a technical term for motorcycle sputtering and the feeling you will experience is an unresponsive throttle input and the motorcycle will spontaneously lose its power.
So now you know what motorcycle sputtering is and what it means and how a motorcycle acts when it sputters.
Common Symptoms Of Motorcycle Sputtering?
Now we will look into the common situations/occurrences when motorcycle sputtering can happen and some of these are early symptoms that can help you identify if your motorcycle is sputtering.
So here are the most common motorcycle sputtering symptoms/signs.
1. Motorcycle Sputtering/Hesitates During Acceleration
The first symptom is pretty easy to notice as the motorcycle sputters when you accelerate.
Motorcycle sputtering or hesitating when you accelerate (high rpm)is due to an uneven supply of air/fuel mixture send to the combustion chamber or a worn spark plug’s weak spark.
This can happen due to a leak or clogged fuel lines or a weak spark by bad or worn spark plugs, ignition coil, or spark plug wires.
2. Motorcycle Sputtering A Wide Open Throttle
The motorcycle will sputter when you roll the throttle wide open because of a bad ignition system, fuel system, or both which work in conjunction to burn the air/fuel mixture and have a successful combustion to produce power.
So when you roll the throttle wide open in a steady or hard manner the motorcycle engine requires a steady flow of air and fuel and a properly time ignition spark to keep the combustion process going at a given rpm.
Bad fuel systems components such as fuel line, carburetor, fuel injector, or fuel return line will fail to deliver the adequate amount of fuel to get burned.
A bad/damaged ignition system components ignition coil, spark plugs/wire, or ignition switch will mistime the ignition of the air/fuel mixture which will result in poor combustion/power stroke.
3. Motorcycle Sputtering During Idle
During idling the motorcycle is at a steady low rpm. Motorcycle sputtering during idling is most of the time due to a clog or leak in the fuel system components of the motorcycle.
The piston moves at a slower pace during idle but an adequate amount of fuel is still required to have ideal combustion.
Bad fuel line, return line, and carburetor/fuel injector will not be able to supply the required amount of fuel and the motorcycle will stutter/sputter at idle.
Now we will look into what causes motorcycle sputtering and the bad/damaged components that play a big role behind a motorcycle sputter.
What Causes Motorcycle Sputtering?
There are multiple causes for motorcycle sputtering and we will go through each one of them in brief detail so you will be able to understand what components of the fuel system or ignition system and a few other parts might be causing the engine sputtering problem.
Note: Some people might say the (engine) timing issue, which means the intake & exhaust valves are opening and closing at the wrong time. It is very unlikely for motorcycle valves to get mistimed on their own, and it can only happen if someone (mechanic or yourself) set the wrong adjustments for the crankshaft and camshaft position and wrong adjustments for TDC timing marks on the flywheel and direction of rotation of the flywheel.
So a mistimed valve will cause severe damage to the engine where the pistons will slam into the valves and cylinder wall let alone sputtering to ever occur.
1. Motorcycle Sputtering Caused Due To Carburetor/Fuel Injector
Whether you have a carburetor motorcycle or a fuel-injected motorcycle, the work of these devices is to send air/fuel mixture to the combustion chamber and air separately through the intake valve for Fuel injected motorcycles.
For an out-of-tune carburetor the ratio of air and fuel sent to get burned will be imbalanced and will result in sub-optimal combustion (burning of fuel and generating power), due to an inadequate ratio of air/fuel mixture the motorcycle will sputter/sutter.
A clogged pilot jet or main jet of the carburetor will restrict the flow of fuel, so cleaning them from time to time is essential.
For fuel-injected motorcycles, the fuel injector will get clogged depending on the quality of fuel and contaminants/carbon buildup over time.
The clog will restrict the fuel supply and the nozzle of the fuel injector will be unable to spray the required amount of fuel into the combustion chamber to get burned.
2. Sputtering Caused By Worn Spark Plugs/Spark Plug Wires
Once the air/fuel mixture is sent to the combustion chamber it will get compressed by the piston before getting ignited by the spark plug.
The motorcycle will sputter if the is any kind of physical damage to the spark plug’s tip or heavy corrosion/breakage to the electrode.
The spark plug will fail to ignite the air/fuel mixture at the right time or will have a weak spark, thus resulting in the motorcycle sputtering.
For spark plug wire, its job is to carry the electric current to the spark plug.
Heavy vibration or coming in contact with a hot surface can detach the wire from the spark plug or can cause a burn/crack to the insulation layer or the wire, which can fail to carry the needed current to the spark plugs to ignite the air/fuel mixture at the right time.
3. Motorcycle Sputtering Caused Due To Clogged Air Filter
For fuel to burn and have a successful combustion air is needed. A clogged air filter will restrict and decrease the amount of air supply to the engine.
The air filter will collect debris, dust, and contaminants over time and will need periodic cleaning services.
Motorcycle sputtering will be a result of a clogged air filter as it will create an imbalance in the ratio of air/fuel mixture. A lean mixture or an extremely lean mixture will be a result of the clogged air filter.
So the burning of the fuel will not be in an optimal and efficient way, this will cause the motorcycle to sputter and loss of power in an erratic manner.
In a few unfortunate cases, the air filter gets wet and can cause the motorcycle to not start, please check out the article where I have shared a holistic maintenance routine for all major types of air filters. ( Click The Underlined Link To Read )
4. Motorcycle Sputtering Caused By Worn Ignition Coil
So all motorcycles carry batteries with a voltage range when fully charged is between 12.7-13.6 volts. To ignite the air/fuel mixture the spark plugs must produce between 20,000-50,000 volts.
The ignition coil transforms the battery’s voltage to higher volts and then sends it to spark plugs to have a successful ignition.
A worn/damaged ignition coil will fail to transform and carry current due to worn spark plugs as it has to compensate resulting in motorcycle sputtering.
Exposure to high temperature, moisture, and vibration can cause damage to the ignition coil.
5. Sputtering Due To Bad Fuel pump Or Worn Fuel Line
The fuel pump, fuel line, and fuel return line job is to supply fuel from the fuel tank to the engine’s combustion chamber.
Excessive fuel can be returned back to the tank through the fuel return line. Clog/leak or breakage to these fuel supply lines or fuel pump will completely stop or decrease the amount of fuel needed to carry out a combustion process.
If there is little to no fuel supplied to the engine, then the motorcycle will sputter or completely stall. So damaged or worn fuel pump and the fuel line will cause motorcycle sputtering.
Bad fuel pump symptoms can be a tricky task to identify, so save yourself a headache and check out this quick article. ( Click The Underlined Link To Read )
How To Stop & Fix Motorcycle Sputtering?
Cleaning carbon deposit build-up and removing clogs and replacing severely worn or damaged components of the motorcycle’s fuel system and ignition system will fix and stop the motorcycle from sputtering.
Removing dirt and clog from the fuel lines, carburetor, and fuel injector will help fuel to flow without restriction to the engine, and engine sputtering will be avoided.
Replacing a bad fuel pump will make sure the fuel is supplied from the fuel tank to the engine’s combustion chamber to get burned.
Replacing or cleaning the spark plug, spark plug wire, ignition coil, or air filter will allow the motorcycle to get an adequate amount of air to the engine and ignite the fuel at the proper time to have an ideal combustion process.
Tuning the carburetor to proper settings will supply a balanced air/fuel ratio to the combustion chamber.
So cleaning or replacing (if needed) these components of the fuel system and ignition system will stop the motorcycle sputtering.
How To Prevent Motorcycle Sputtering?
Periodic cleaning and maintenance service of the ignition system and fuel system components is necessary to prevent motorcycle sputtering. As maintaining these parts will efficiently provide the right ratio of air/fuel mixture and ignition at the right timing.
So the motorcycle will never face the problem of sputtering if a holistic maintenance routine is in place.
Cleaning carbon deposits, and dust/debris along with other maintenance checkups as discussed in this article from time to time will prevent the motorcycle from sputtering.
Is not that complicated as maintenance and servicing from a quality mechanic or by yourself (if experienced) is enough to keep the motorcycle running smoothly and properly.
Motorcycle Sputtering FAQ
Is Engine Sputtering & Misfire Same?
There is a slight difference between engine sputtering & misfire. During a misfire the engine cylinder completely misses one of the strokes of the combustion cycle, whereas during sputtering the motorcycle sputters/stutters due to faulty fuel or ignition system and performs a sub-optimal combustion process.
