Motorcycle Won’t Kickstart | Here’s Why (Solved)

Most older bikes were made to kick start by applying force to an external crank arm.

In many cases, the kickstart was replaced with an electric motor starter, but a lot of dirtbikes have retained this feature because it is a very mechanically sound way to start a motorcycle.

If your motorcycle won’t kickstart, we’ll run through some of the causes and ways you can correct the issue and have your bike starting up right away.

What Is a Kickstarter and How Does It Work?

Kickstarters are the original way to start an engine, before the invention of the electric starter systems most manufacturers use today. Older bikes and a lot of dirt bikes will have a kickstarter in place of an electric starting system.

Kickstarting employs an external lever hooked up to the engine’s crank that uses capacitor discharge instead of a battery to create the spark needed for the motorcycle’s engine to start.

By forcing the lever down and opening the throttle to induct an air-fuel mixture into the combustion chamber, your bike will start up, but not always on the first kick.

That’s because the motor must be in the top dead center (TDC) position for the crank to turn over properly. To find TDC correctly, you have to gently crank the kickstart lever several times to build up pressure in the cylinder.

Once you feel resistance on the lever, you must decompress the system before your full kick to avoid kickback on the lever. This can cause some serious injury and can even throw you off the bike.

A lot of motorcycles now are equipped with a built-in decompression element, but some models, especially older ones, will have a decompression lever (usually on the left side of the bike below the handlebars).

Finding TDC and then pulling the decompression lever will put your piston in the correct placement inside the cylinder. When you are in the correct spot, kickstarting the bike should be a breeze.

Always kick down firmly, but avoid excessive force because you don’t want to break the kickstart lever or injure yourself from kickback. Follow through on each kickstart stroke.

Why Won’t My Motorcycle Kickstart?

There are several factors at play that allow a kickstarter to work properly.

If you have a broken kickstarter, an incorrect mixture of fuel/air, issues in the ignition system, or simply a flooded engine, then your bike won’t kickstart properly.

Let’s break down some of these issues to help you troubleshoot the problem!

1. Engine Is Flooded

One of the most common and equally frustrating issues when kickstarting a bike is a flooded engine. What this means is that the bike has induced too much fuel for the spark plug to ignite the mixture in your engine.

This happens when there are multiple attempts to kickstart the motorcycle, inducing the fuel into the system. This can leave you continuously cranking on an engine that won’t be able to start at all until the fuel has evaporated enough to allow for full combustion. 

If the engine is flooded, not to worry-just wait a little while and let the amount of fuel in the chamber subside. Now, using the proper kickstarting technique, start the bike. It should roar right up.

If you keep cranking on it, though, you will just get more and more frustrated. Patience is a virtue!

2. Kickstarter Is Not Properly Decompressed

One factor that can keep the bike from kickstarting is compression in the cylinder. This is one of the most common culprits for a flooded engine.

If your bike has a decompression lever, squeeze it every time you’ve come to TDC and are ready to kick down the bike.

If the cylinder chamber around the piston isn’t properly decompressed, the piston will kick back at you, which is very painful. We know; we have the receipts.

Related: How To Start A Motorcycle With A Bad Starter (Solved!)

3. Kickstarter Is Broken

The kickstart lever on your bike uses a spring inside the mechanism to return the kickstarter to its original position. If the spring is broken, you’ll be able to kick it down, but it won’t return back up. 

The spring can corrode over time and all it takes is one last crank to break it. It should be noted that overly aggressive kicks on the lever can greatly reduce the lifespan of your kickstarting mechanism, spring included.

It is important to remember that kickstarting shouldn’t be too bad.

You should be able to use your leg (or in the case of smaller riders, your body weight) to firmly kickstart the bike without using excessive force.

If the kickstart function of your bike is broken, it will need to be replaced and you should never ride a bike with a broken kickstarter. Not only will it leave you stranded out on the trail, but it can cause further damage to your engine.

Have a trusted professional replace your kickstarter. Even though it’s an outdated and relatively simple mechanism, it’s not a job for the novice mechanic.

4. Clogged Fuel Filter, Blockage in the Fuel Line

The correct air/fuel mixture is needed for your bike’s engine to turn over, but if it isn’t getting the right amount of fuel, you’ll spend a whole day cranking away at your kickstarter with no results.

The fuel filter between your bike’s fuel tank and fuel delivery line can get clogged over time with small amounts of debris or gunk from cheap fuel. 

If you have been troubleshooting your starting issues and have determined that the issue is not enough fuel, you’ll need to do some basic disassembly to check the fuel filter. 

Once you’ve removed the filter, check for blockage. It’s highly recommended that you replace it with a new fuel filter because any debris or gunk in the fuel that finally gets to the engine can cause catastrophic damage to the engine over time.

By replacing a clogged fuel filter, you should be able to kickstart your motorcycle with no problems.

Related: Motorcycle Won’t Start & Smells Like Gas (Solved & Explained)

5. Problems in the Ignition Line

Ignition is the point in your bike’s system that utilizes electrical discharge to start your bike. This is in the form of a spark, which is generated by your spark plug. 

There are a couple of waypoints in your ignition system that can drastically affect your engine’s ability to turn over.

One reason your motorcycle might not kickstart properly is a bad CDI box. The CDI is a capacitor discharge ignition component that pushes the ignition process into motion. 

If your CDI box is bad, it’s not going to send the discharge of electricity needed to create a spark and will need to be replaced. This repair requires removing the gas tank and wheel cover, as well as electrical testing, using a voltmeter. Remove the tank and locate the CDI box. 

Test the power > outside of the system. If it shows no voltage running out, it is bad, and that’s why you haven’t been able to kickstart your motorcycle.

Simply replace the CDI box with a properly functioning one and you should be good to go!

6. Worn or Damaged Spark Plug

The spark plug is the final piece of the ignition system puzzle and a good thing to check if your motorcycle won’t kickstart.

Spark plugs utilize voltage to produce the spark at the top of your engine that is required for combustion. A faulty spark plug can render the whole system useless.

Fortunately, spark plugs are easy to diagnose and replace!

Remove the spark plug wire boot and unscrew the spark plug from the engine head. Be sure you don’t let anything fall into the spark plug void. It is incredibly hard to remove and can cause catastrophic engine failure.

Is the spark plug cracked? Corroded? It will need to be replaced. Fortunately, this is a simple and cheap fix-I wish all motorcycle diagnoses could be remedied by something as easy as the spark plug!

7. Dirty Or Detuned Carburetor

A carburetor is the magical place on a motorcycle where air and fuel are mixed on older bikes or any bike that doesn’t rely on modern fuel-injection technology.

Because carburetors are delicately tuned to the specifications of your bike, dirt, fuel gunk, and time will ultimately lead to malfunction.

It’s a relatively easy thing to clean out, but the tuning of a carburetor can be very difficult for the novice mechanic.

To clean the carburetor, remove the air intake that leads to the carburetor unit.

Often, if your carb isn’t too dirty, you can simply spray a good amount of carburetor cleaner into the air intake side of the carb. This should clean out any fuel gunk or dirt.

If this doesn’t solve the issue, you may need to remove the unit and do a thorough cleaning.

A properly functioning carburetor is essential to the proper function of the bike, especially the ability to kickstart the engine.

Related: Motorcycle Stutter When Accelerating? Here’s Why (SOLVED)

8. Clogged Fuel Injector

For newer bikes, a fuel injection system is used to add fuel instead of mixing it in a carburetor. Fuel injectors have very small nozzles that allow the fuel into the combustion chamber.

Any debris or gunk caused by using low-grade fuel can easily clog these nozzles.

If any fuel ports in your fuel injection system become clogged, your bike won’t receive the proper amount of fuel to kickstart.

Cleaning these out is doable. Make sure you look up the process and specs for your specific fuel injection system.  

Sources

How A Kickstarter Works | ScienceABC.com

How A Dirtbike Kickstarter Works (How To Kickstart My Bike) | DirBikeEarth.com