Why A Motorcycle Won’t Start: The Perfect Answer You Need To Know

If your motorcycle won’t start, then there are some things you will have to check. That said, nothing is quite as disappointing as wearing your helmet, getting on your bike, and trying to start it to no avail.

When this happens, it is likely that you will feel frustrated and disappointed by your motorbike. However, before you decide to call it quits and use an alternative vehicle to your destination, you should first try to understand why your motorcycle won’t start.

That said, the main components in an ordinary bike that cause it to run include compression, air/fuel mixture, and spark. This means that a bike will either refuse to start or run rough if it doesn’t have the right amounts of any or all of these components.

Therefore, you will have to break down each of these elements, troubleshooting every one of them until you get to the root of the problem. Use the guide below to help you do exactly that

What You Will Need To Check

So, what do you need to check when your motorcycle won’t start. Consider the following

1. Ignition Spark

In most bikes, electrical problems are relatively difficult to troubleshoot – especially if you haven’t been riding for long. Most riders take the electrical system on their motorcycle for granted until something is awry. However, before tear your bike apart, you first need to check for some key issues. These include

  • Ensure that your key is correctly turned to RUN or ON
  • Check whether the kill switch is also in the RUN position
  • Ensure that your motorbike is in the neutral position and that the kickstand is up

After you’ve resolved the above, try to start your motorcycle again. If it fails, you should investigate your engine spark a bit further. This will include checking

a) The Spark Plugs

When you get here, you can trace the issue until you get to the root of the problem. To check your plugs, get them from the cylinder head, remove them, then plug them right back into the plug cap.

b) Head Bolt

Holding the spark plugs up to any piece of metal (such as the head bolt), turn over your engine. If you do it correctly, you’ll see a spark from the electrode going towards the metal part.

If the spark is weak or non-existent, check the battery of your bike or change your plugs. Then, see if you get better results. If not, continue below

2. Fuel Air Mixture

With regards to the fuel and air mixture, you also need to check for some obvious issues. For instance, as you continue wondering why your motorcycle won’t start, find out if the fuel petcock is on reserve or turned on. Similarly, check if you have gas in the tank.

a) After Storage

Most riders encounter fuel problems when they try starting a bike that was in storage for a considerable period. Gas tends to break down over time especially if you didn’t stabilize it properly. When combined with ethanol, gas will also break down even further and faster. The key here is to always use fresh gas.

When a motorbike sits for long durations, the fuel system might also dry out. Therefore, you should check the fuel lines to ensure that the gas is getting to your throttle body or carbs.

b) Dry Fuel Lines

At times, fuel lines on bikes tend to dry out before cracking. Similarly, fuel filters might become plugged, making it difficult for them to allow enough (or any) gas to pass through.

In older carbureted motorcycles, you will need to use some carb cleaner or starting fluid. Spray it into the carb intake before you start your bike. When the engine fires the starting fluid, it will also draw the gas right through the fuel system.

However, if the bike continues dying even after you’ve run the starting fluid, consider other problem areas. Remember, even starting fluid won’t lubricate all the cylinders properly – particularly after extended use. As such, you should only use it sparingly.

Clogged vent tubes in the gas tank might also restrict the flow of gas through the entire bike system.

c) Flooding

Another one of the fuel issues to check when your motorcycle won’t start is flooding. The best way to un-flood an engine is by removing the spark plugs, turning the choke off, and turning your motor over to drain all the excess gas. If you have time, allow the motorcycle to sit until everything evaporates.

d) Dirty Carbs

If you’re at this point and the motorcycle won’t start, you should clean your carbs. When old gas breaks down within a bike’s carburetor, it might leave green gunk behind. This gunk blocks the jets in the system. After cleaning your carbs, therefore, you should ensure that the fuel pump is working well.

e) Broken Loose Vacuum Lines

Of course, bikes need the perfect amount of air to mix with gas for them to start. A loose or broken vacuum line might cause too much air to be drawn into the bike’s combustion chamber. This will, inadvertently, alter the mixture of air and fuel. As a result, your engine won’t be able to ignite the mixture well. Therefore, you should check the vacuum lines for any holes or cracks.

Conversely, the culprit behind why your motorcycle won’t start might be that the airflow is too little. To correct this, check to see if air can easily pass through the air intake filter. If the filter is dirty, you know what to do.

3. Compression

When your motorcycle won’t start, test for compression. The result from this test might prove to be the most devastating. That said, your motorbike’s engine won’t fire up properly (or at all) if any of the cylinders have low (or no) compression.

You need to compress the air and fuel mixture to raise the temperature to a point where the mixture burns. Unless the compression is adequate, therefore, your mixture will refuse to ignite.

A compression tester can help you when you need to check the bike’s compression. Some of the causes of low compression to check for include

  • Worn out piston rings
  • Scored cylinders
  • Scored pistons
  • Worn crank seals
  • Worn head gaskets

You’ll need quite a bit of money and time to fix these issues in comparison to the problems discussed above. Talk to an experienced motorcycle mechanic for help.

Step By Step Intructions

To outline the above solutions to why a motorcycle won’t start, consider these steps

  • Check the easy stuff first; for instance, find out if you’ve turned on the ignition
  • Open the float bowl drain then check if the fuel that runs out is clean
  • With the key on and the discharge line disconnected, find out if the pump pushes fuel out
  • Check the fuel flow if you’re using a remote pump tank; locate the fuel pump under the bike’s side cover; then, get rid of the discharge side hose
  • If there’s no fuel flow, check the filter
  • Sometimes, the clutch safety switches goes bad as does the kickstand safety switch
  • Bypass both kinds of switches using a short piece of wire

Final Verdict

Finding the problem when your motorcycle won’t start is the first step to correcting it. Hopefully, this guide should help you do exactly that. Use the steps above – going through each one carefully – the next time your bike refuses to power up.

I hope you enjoyed this article, please leave us your feedback in the comment box below. Share it with your fellow biker friends if you think it’s helpful.

1 thought on “Why A Motorcycle Won’t Start: The Perfect Answer You Need To Know”

  1. Puts the process of fault finding into perspective.

    Very good.

    I’ve just finished a rebuild on my ‘1973’ Triumph T150 and the thing won’t start, despite looking beautiful, in this case it’s a carb problem as when checking the plugs they are dry but a big fat blue spark! Anyway on with the investigation.


Leave a Comment

54  +    =  60