2 Cycle Engine Hard To Start When Hot [5 Easy Solutions]

2 Cycle Engine Hard To Start When Hot! It’s a common serious problem every 2-stroke bike goes through. Generally, an oil mix problem, engine flooding, and carburetor issue are the culprits that make it hard to start a 2-cycle engine.

Therefore, dirty air filters, dirty spark plugs, and adding improper oil are the culprits that are also responsible for this issue. 

If you want to make the 2-cycle engine start easier, you must address and solve the problems we mentioned. And this 2-cycle engine troubleshooting guide will help you fix the hard starting issue. So, keep reading. 

2 Cycle Engine Hard To Start When Hot [5 Easy Solutions]

Don’t know how to diagnose a hard-starting hot engine? Then, check out the following guides that will help you determine the reason behind a hard-starting engine. 

1. An Oil Mix Problem

A 2-stroke engine is a bit finicky. If you fail to pour the correct fuel-to-oil ratio into the engine, the 2-stroke engine will struggle to start. At worst, it could produce carbon buildup in the internal moving part of the engine.

Indeed, the hard starting problem is from an oil mix issue that is not ideal for the conditions. So, spending hours tinkering with the bike will get you no luck. 


If there is an oil mix issue, you can easily overcome this problem by pouring the correct mix ratio. The most common mix ratios are 50:1 and 40:1. 50 to 1 means there are 50 parts of fuel to one part of oil when mixed. We recommend you check the manual and use the ratio the manufacturer suggests. 

2. Flooding Problem

Flooding refers to extra oil in the combustion chamber. Excess oil causes the engine unable to ignite, which makes your 2-cycle engine hard to start. Several culprits are responsible for a flooded engine, including: 

  • Over-priming– it is actually putting too much fuel into the engine. 
  • Closed choke– It (choke) is a dial. If it’s in a close position, you will experience the engine flooding issue. 
  • The air filter gets dirty
  • A clogged carburetor

We recommend you check out this video to learn about more reasons that are responsible for an engine flood. 


You can easily solve the engine flooding problem by pulling out the spark plug. Once you remove the spark plug, we recommend you set the choke to deactivated mode. Then, try to start your 2-stroke engine until the combustion chamber gets empty or clear. Now, dry the spark plug using a sponge or cloth, put it back into its place, and start the engine. 

3. Condenser Goes Bad

The 2-cycle engine will not start when hot if the condenser gets defective. It is a small part of the ignition system used on most 2-stroke or small engines. It works like a voltage capacitor and stores a high-voltage charge. Several contacts are used to send the charge to the spark plug. 

If the condenser goes bad and doesn’t throw off enough voltage to the fire or spark plug, your small or 2-cycle engine won’t start. It’s a common problem and you can easily fix this issue without spending a lot of bucks. 


You should run a test to check whether a condenser functions properly or not. Fortunately, it doesn’t take a lot of elbow grease or experience to test the condenser. Just take a multimeter and switch it to the OHM position. 

Then, insert the red lead into the ‘ohm’ connector and the black one into the common connector on the meter. 

Now, touch the hot connector of the condenser with the red lead and place the black lead on the metal case of the condenser. If you do this correctly, you can see the movement of the needle. It means your condenser is good. Otherwise, you should replace the condenser to fix the issue. 

You can check out the video as well to watch how to test a condenser. 

4. Carburetor Problem

We can compare the carburetor with the heart of a human. Without a healthy heart, we can’t lead a healthy life.

In the same way, your engine will not run properly if the carburetor gets dirty or clogged. A knocking sound, black smoke out of the exhaust, and a flooded engine are some signs of a bad carburetor. 


If the carburetor gets clogged by dirt, the combination of air and fuel your engine requires will not travel through the passage to the 2-cycle engine.

In this, you just need to clean the carburetor to let the engine start again. We recommend you check out this video that will help you solve the carburetor issues. 

5. Spark Plug Gets Dirty

A dirty spark plug is what causes hard starting when the engine is hot. If the insulator nose at the firing tip becomes coated with a foreign substance such as fuel, oil, and carbon, the spark plug starts fouling or malfunctioning.

If the spark plug gets dirty, it will not provide adequate voltage to the firing tip and the cylinder will not fire properly. 


The easiest solution is to replace the spark plug. It’s because, in many cases, you can’t clean the spark plug sufficiently to restore normal operation.

So, it will be best to replace the spark plug with a new one once the spark plug gets fouled. If you don’t know how to change the spark plug on a 2-cycle engine, watch this tutorial. 

How Do You Make A 2-Stroke Start Easier?

You already learned what causes a 2-cycle engine hard to start when hot. For example, an improper fuel-to-oil ratio, a bad carburetor, fouled plug, and a dirty air filter is the culprits that make it hard to start a 2-cycle engine. We recommend you address these problems first and solve them. 

Two-cycle engines are pretty straightforward in construction and should start with 2-3 kicks. But the culprits we mentioned make the start difficult. 

Also, make sure your 2-stroke engine is in good condition. Ensure the piston rings don’t get worn out. Lastly, make sure there are no fuel leaks from the fuel system. We hope you can make a 2 stroke start easier if you solve these issues and add the correct oil, maintaining the oil mix ratio. 

How Do You Adjust A 2-stroke Carburetor?

Follow the below steps to adjust a 2-stroke carburetor:

  • Find the two adjustment screws on the carburetor. One screw is for high speed, and the other one is for low speed or idle. 
  • Turn both screws counterclockwise to set them in the ‘open’ position. 
  • Now, turn both screws clockwise to full turn. And it will be the starting point for customizing the carburetor. 
  • Next, turn on your engine and leave it for two to three minutes to let it warm.
  • Then, you can adjust the choke lever if needed to start your 2-cycle engine. 
  • In this stage, move the low-speed screw clockwise for idle speed until you hear the engine stalling sound. Then, turn the screw counterclockwise from 1/4 to 1/2. 
  • Operate your engine at high RPM by holding the throttle. Turn the screw counterclockwise for high speed until your engine starts to run smoothly. Finally, turn the high-speed screw 1/4 turn clockwise.


How Do I Know If My 2 Strokes Has Low Compression?

Your 2-stroke engine has a low compression if you find it hard to start. Therefore, fouled spark plug, low power, and improper idling are the signs that will indicate your 2-stroke has low compression.

Will a 2 Stroke engine start without oil?

Yes, you can start a 2-Stroke engine without oil. But the heck is- you can’t use this oil for a long time. This small amount of oil fails to lubricate the bearings and rings. And it will bring ultimate destruction to your engine. 

What happens if you mix too much oil in a 2 stroke?

If you mix too much oil in a 2-stroke engine, it will generate too much smoke. Turns out, the oil will come out from the muffler if you add excessive oil. 

Can you use starting fluid on a 2 Stroke engine?

You can use starting fluid on a 2-stroke engine, taking proper precautions. Generally, a 2-stroke engine uses oil mixed with gas for proper lubrication. If you use too much starting fluid, it may damage the engine. In this case, you must quickly wash away the fluid and add oil to prevent severe engine damage. 


The 2-cycle engine won’t start when hot due to a bad carburetor, dirty spark plug, and an oil mix problem. Fortunately, we broke down how to fix those issues. So, follow the troubleshooting steps we mentioned.

If you are not mechanically inclined, we recommend you to bring your 2-cycle engine to a professional. 

About John M

John contributed as a technical head at an automobile company just 2 years after his post-graduation in Automobile Engineering. He loves to lead a free life, so he left his job & started blogging. Now, he does research on every automotive problem, part & product and seeks a better solution & best products & shares his findings with his readers to help them as well as to minimize their struggle.

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