Can A Motorcycle Run Without Spark Plugs? (Explained!)

Spark plug tip on a black background

Spark plugs are an essential component in gasoline engines.

Since motorcycles that run on fuel use gasoline engines, spark plugs are vital for motorcycles as well.

So, can a motorcycle run without spark plugs? Without spark plugs, the gasoline engines in motorcycles will not even start. As a result, motorcycles cannot run or even start without spark plugs.

That’s the short answer.

Now, let’s discuss in detail:

  • Will a motorcycle start without the sparkplugs
  • Role of spark plugs in engines
  • Does kickstart or crank start help when there is no spark plug
  • Spark plugs in diesel engines

Will A Motorcycle Start Without The Sparkplugs?

All conventional motorcycles run on gasoline engines. And gasoline engines need spark plugs to keep running. Without a spark plug, a gasoline engine will not even start.

And as a result, a motorcycle will not start without a spark plug.

Gasoline engines, which the motorcycles use, always have spark plugs installed within them. What a spark plug does is – it ignites the gasoline fuel mixture in the combustion chamber by creating a high voltage spark.

This spark ignites the fuel mixture in the chamber. Leading to the burning of the fuel and thus, releasing energy within the engine. That’s how the engine combusts the fuel and generates power.

So, the fuel burning starts with the spark plug providing that spark and igniting the fuel. This cycle of spark ignition goes for each combustion cycle in the engine.

The fuel mixture enters the engine through the inlet valve first. The air-fuel mixture is then compressed by the piston moving up with the engine cylinder.

Unlike in diesel engines, this compression of the fuel is not enough to ignite the fuel in gasoline engines.

And that’s where the spark plugs help.

At the end of the compression phase, the spark plug provides the electric spark – igniting the fuel. This ignition leads to the combustion of the fuel within the chamber. Once the fuel is burnt, energy is released, and exits out the engine through exhaust valves, a new set of air-fuel mixture enters the engine again. This cycle continues.

So, you get the idea. The spark plug is the component that ignites the fuel mixture in the combustion chamber.

Needless to say, without a spark plug, the engine will not start. So, a motorcycle will not start without a spark plug either.

What Does A Spark Plug Do Exactly?

A Spark plug in an engine produces a high voltage electric spark to ignite the air-fuel mixture in the engine.

The spark produced will be in the range of 15,000-20,000 volts. When the air-fuel mixture is getting compressed in the chamber, the spark ignites to burn the fuel mixture.

As a result, the fuel burns to generate power in the engine. Effectively pushing the piston down in the cylinder chamber – which, in turn, is used to transfer this mechanical power into the crankshaft.

In short, a spark plug produces that electric spark to ignite the fuel in the engine for its combustion.

Can I kickstart a motorcycle without the spark plugs?

You cannot kickstart a motorcycle without spark plugs in the engine.

A kickstart may make the engine to start operating. But, since there won’t be any combustion because there are no spark plugs to ignite the fuel, the engine will stop even before it starts.

Eh, that’s a bit confusing. Let’s just say the engine won’t start. Try all your power on kickstart as you can.

I know we all think kickstart is the shutdown and restart for motorcycles. But it has no power here.

Kickstart helps when there are problems in self-start or the battery. But a dead spark plug or no spark plug is something that a kickstart cannot fix.

Can You Crank The Engine Without Spark Plugs?

This is getting repetitive. Still, bear with me.

Even if you try to start the engine either through kickstart or cranking the engine through any means – it does not matter.

As long as there is no spark plug, the engine won’t run.

Gasoline engines need, let me make it clear, gasoline engines absolutely need spark plugs to ignite the fuel and run.

It does not matter at all whether you are trying to crank start the engine. The engine will not run if there is no spark plug in the engine.

Do All Engine Not Start Without Sparkplugs?

Only gasoline (petrol) engines need a spark plug to start and combust. Diesel engines, which start on compression ignition, start without any spark plugs.

In fact, diesel engines do not contain spark plugs at all.

That’s one of the major differences between gasoline engines and diesel engines.

While gasoline engines need spark plugs to ignite the fuel and start the combustion process, diesel engines have no need for electric spark.

High compression of the fuel will suffice for diesel engines. That’s all they require for the engine to start the combustion process. And generate power.

A typical diesel engine will have a compression ratio of 22:1. On the other hand, a gasoline engine will usually have a compression ratio of 8:1.

And compression ratio, put simply, measures the level of compression by taking the ratio of engine cylinder volume before compression to after compression. The higher the compression ratio, the higher has been the compression. Duh!

That’s why diesel engines do not require spark plugs. Highly compressed air is enough to ignite the diesel in the engine and start the combustion.

ParametersGasoline EngineDiesel Engine
Fuel UsedGasolineDiesel
IgnitionSpark ignitionCompression ignition
Contain Spark PlugYESNO

But, Diesel Engines Have Glow Plugs

Diesel engines do not have spark plugs in them. They don’t need it as discussed above.

But they do have a component called a glow plug. What a glow plug does is it heats the diesel combustion chamber which is useful in cold conditions.

The compression ignition in diesel engines might get ineffective in cold conditions. The low temperatures make the diesel unable to ignite simply due to the compression.

To address this concern, glow plugs are installed within diesel engines.

These glow plugs preheat the combustion chamber. The diesel, despite cold conditions, will start combusting with the compression ignition easily. That’s why glow plugs are handy in diesel engines.