Even with a fully charged battery running at peak voltage, a motorcycle won’t start.
This can be incredibly frustrating, especially if you’re all geared up and ready to ride!
If you’ve confirmed that your battery is good, but the bike still won’t squeeze the juice and make the rumbles, we’ll help you figure out why!
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Here’s the short answer to why your motorcycle won’t start even if the battery is ok:
Several factors can cause your motorcycle not to start even when the battery is fully charged and healthy, including a faulty electric starter and damaged spark plug. An empty tank, defective wiring harness and engaged kill switch, leaking vacuum lines and disengaged fuel valves can all prevent your bike from firing up.
Simple Machines, Simple Problems, Simple Solutions
One of the greatest advantages that motorcycles have over more complex vehicles is their sheer simplicity. Even with a functioning battery, a bike won’t start if you lack air, fuel, or spark.
There are also electrical systems on most modern motorcycles that require a bit of attention to detail, but with the correct tools, most anyone can troubleshoot their starting issues.
Almost all motorcycles run on 12-volt batteries. A 12-volt battery, when tested, should read on your meter as being between 12.6 and 12.8 volts. Anything below that indicates two things-a bad battery or a voltage leak somewhere in your electrical system.
Every time a motorcycle won’t start, it is important to go through what we like to call the ‘dummy check.’ This is a visual inspection that requires a bit of attention, but not so much that you can’t figure out what the issue is!
In any visual inspection, it is important to check your fluids, exterior components, and simple interior components such as spark plugs. Often a misread fluid level, visible fault in cabling or lines, or simply not pushing the right button, toggle, lever, switch, or plunger can be the most obvious culprit.
Fear not, motorcycle rider! We’ve compiled a list of 10 reasons a motorcycle won’t start, even if the battery is fully charged.
1. There Is No Fuel in the Tank
If the bike sounds like it wants to start, but just won’t turn over, pop off that gas cap and take a peep inside the fuel tank. Is there fuel? Then you can feel free to move on to another section on our list of reasons a motorcycle won’t start even if the battery is good.
There’s no shame to it, folks. Sometimes we just forget to fuel it up on the way home. Shoot, sometimes we buy the fuel at the station and get so wrapped up in eating a candy bar that we ride away without getting the gas we paid for.
The point is, there’s no reason to kick yourself over forgetting to fuel up the bike. Just don’t tell anybody about it and you should be fine.
When a motorcycle has been run completely out of gas or has been drained for storage, let it sit for a minute or two after refilling the tank. That way, the fuel has time to get all the way through the lines.
2. The Electric Starter Is Bad
The electric starter replaced the kick starter so long ago that, save some dirt bike models still in rotation, chances are your bike starts up with an electric starter. This electric feature of your motorcycle sends an electrical signal to the starter motor and, presto! The bike is running.
Unfortunately, the only downside to the near-flawless design of the electric starter is that, just like any other part, it can go bad, become faulty, and leave you stranded without any other way to start the bike.
When a starter goes bad, it isn’t necessarily all bad news if you’re worried that you’ll have to shell out even more clams for a new, sometimes expensive part. Some elements within an electric starter can be rebuilt and replaced-check your service manual to see if this is the case.
Test your starter with an electric voltmeter. If your readings don’t come up as noted in the service manual, you’ll need to replace those parts, or the electric starter entirely.
Even if it seems like a hassle, a properly functioning electric starter is one of the most important parts of your motorcycle. Without it, you’ll be stranded for good, so it is a top priority to check if your motorcycle won’t start even if the battery is OK.
3. Kill Switch Must Be Off
Most motorcycles have a kill switch. This is often a button, toggle, or switch on the right side of the handlebar, close to the electric starter button or switch.
Even if your battery is fully charged and all the other parts of the starting system are functioning perfectly, the kill switch will prevent the starting system from completing the circuit.
A kill switch works like a little contactor. The next part confused me forever, but I’ll explain it in a way I hope makes sense.
Usually, there is an ‘On’ label and an ‘Off’ label on the kill switch. Flip it on and your bike will run when started. This is actually the ‘Off’ position for the kill switch. It took me some time to figure this out, but I hope this helps you understand it!
4. Fouled Spark Plugs
In an ideal world, motorcycles would always run the exact air/fuel mixture into the engine without any fault. This is unfortunately not the case, and an improper mixture will foul your spark plugs.
When the tip of the spark plug is too fouled up, it won’t make the spark necessary to combust the fuel in the engine and your bike won’t start.
This is an easy fix, and even people with little mechanical experience can test, troubleshoot, and fix it in 3 easy steps!
- Using the correct spark plug socket size, remove the spark plug/s from the engine head.
- Visually inspect them for black, sooty tarnish (overly rich mixture) or white, chalky fouling (overly lean mixture).
- If the spark plugs are too tarnished to produce a spark, replace them with inexpensive new spark plugs!
5. Fuel Valve Is Off
The fuel valve, or petcock, is usually located right under the fuel tank where the fuel feeds into the line. If there isn’t any residual fuel left in the line from the last time the bike was running, and no gas is entering into the lines because the fuel switch is off, the motorcycle probably won’t start.
We’ll chalk this up as one of the head-smackers (“Why didn’t I check that first?”).
6. Fuel Lines Are Clogged
Fuel lines can become clogged over time with debris, sediment, bad fuel, or ethanol byproduct build-up within the line. If there is any clogging in the fuel line, the proper amount of gas won’t be able to get the bike going.
Fuel lines can be pretty easy to troubleshoot, but make sure to have gloves, rags, and an empty gas can handy to get this one right.
At the fuel tank, turn the fuel valve to the off position and work your way down the fuel line. With each section of fuel line tubing, remove the hose clamps at every section, open the fuel valve to let fuel flow freely, and check to see if you’re getting the proper amount of fuel.
The proper amount of fuel flowing through your fuel lines can be measured in milliliters per second, and this metric will be in your service manual.
If there isn’t enough fuel traveling through a section or no fuel at all, go ahead and replace your fuel line! Fuel lines are relatively inexpensive, so please consider replacing the entire fuel line if you have to replace one part.
Chances are if one section is clogged or clogging, the other sections will have the same sediment, debris, bad gas, or ethanol leavings in them as well.
7. Leaking Vacuum Line
Any air leaks in your vacuum line can have dire consequences for starting a motorcycle. Do a visual inspection of the air intake inward. If you see any cracking in any of the plastic, rubber, or clamping components, you may have found your issue if your motorcycle won’t start.
Too much air can suck into your engine with too little fuel to allow for a good enough combustion to get your engine going, and it can also negatively affect your engine performance in the long run.
Unfortunately, the best way to diagnose a vacuum leak involves a test when the engine is running, but go ahead and tighten all your clamps, boots, and any gaskets in your vacuum line to see if it helps the problem. Even the smallest of vacuum leaks can keep a bike from starting.
8. Fuel Pump Has Stopped Functioning
A lot of motorcycles use a gravity-fed fuel system, but if your fuel pump has gone bad, you won’t be getting the fuel you need to get the bike going!
Assuming your battery is fully charged, turn the key in the ignition. If your bike has a fuel pump, you should hear a distinct whirring sound. This sound is the fuel pump priming itself full of fuel to properly operate once it is needed to deliver fuel throughout the duration of the ride.
If you don’t hear any whirring, you’ll need to replace it. Check your service manual for the correct part and replacement procedure.
9. The Side Stand Is Down
Surprisingly, newer motorcycle models won’t start if the side stand is down. Much like the kill switch by the starter on the handlebar, the side stand (kickstand) has a little contactor switch in its mechanical arm that will prevent a motorcycle from starting, even if the battery is fully charged.
Simply straddle the bike, find your center of gravity, pop up the side stand, and try to start the bike. This could very well be one easy reason your motorcycle isn’t starting!
10. Air/Fuel Mixture Isn’t Rich Enough For A Cold Start
Carbureted motorcycles have a choke function that enriches the air/fuel mixture for rough starts, hard starts, and cold starts.
Determine whether your motorcycle has a choke plunger or lever and engage it. This is called choking your bike.
If your bike starts up right away, then you just needed that little extra bit of fuel, and off you go!