After repairing motorcycles for the last 30 years I have compiled the top 10 things to look for if your motorcycle won’t start but turns over. None of us likes to be stranded especially with fuel-injected motorcycles that are all electronic nowadays.
With some basic DIY knollege and some simple tools you should be able to get your motorcycle back on the road fast.
Table of Contents
- 1 1. Flat battery
- 2 2. Bad Fuel
- 3 3. Air Filter blocked
- 4 4. Faulty battery terminals or earth connection.
- 5 5. Fouled spark plugs.
- 6 6. Ignition coil or leads shorting down to earth.
- 7 7. Kill switch
- 8 8. Fuel Pump
- 9 9. Blown head gasket
- 10 10. Starter relay
- 11 Motorcycle not turning over fix.
- 12 Motorcycle wiring diagram explained
- 13 Conclusion
1. Flat battery
This is the number 1 reason motorcycles won’t start but turns over. If your battery is extremely flat you may only hear a ticking sound. This is the starting solenoid kicking in and out.
The best way is to place the motorcycle battery on charge overnight. I use a Ctek smart motorcycle battery tender charger which is proven to prolong the life of your battery. If you need to get on the road fast you could get a jump start from a car, another motorcycle, or a portable jump starter with an inbuilt air compressor. These are great for motorcycles.
Because the battery is hard to access on my Yamaha MT07 I have installed a short fly lead so I can quickly remove the rear passenger seat and charge the battery. It is a 10-second job now to top up the battery.
2. Bad Fuel
If your motorcycle is left in the rain or you don’t use it for a while you could get water in your fuel. Check the fuel tank lid that the seal is in good condition.
If you have a bad motorcycle cap seal when it rains water will be able to enter the fuel tank.
If you suspect that you have bad fuel you can undo the fuel line going from the tank to the fuel pump/carburetor and drain the tank into an approved container. Take care to not set yourself or your motorcycle on fire. A blocked fuel filter can also cause your motorcycle not to start but to turn over.
Refill your tank with primium octane fuel. This will provide you with cleaner burning, higher power, and easy starting fuel.
In the USA Premium is the highest octane fuel–generally 91–94 AKI. In other parts of the world like Europe and Australia, the Premium octane fuel is 98 RON.
3. Air Filter blocked
Motorcycle air filters need to be changed out every few years. This will keep good airflow to your engine. Over time the air filter can get blocked with dust, insects, and even moisture.
This will restrict airflow and cause your motorcycle to run rich which can cause hard starting issues.
Replace the air-filter regulary so your engine can breath easy. A blocked air filter will cause trouble starting your motorcycle.
4. Faulty battery terminals or earth connection.
Overtime motorcycle battery terminals can corrode and cause a hot joint. This resistance will cause a drop in voltage from the battery to the starter motor. If you notice white or green powder on the positive terminal you may have a hot joint.
Clean the active and neutral battery terminals with water and 300 grit sandpaper. Once the copper clamps are clean and dry you can bolt it back down. Any leakage from the battery acid can also cause corrosion on the battery terminals.
Check the main neutral earth cable that it is attached to the frame and or motor. Clean the terminals and tighten it up if it is loose.
5. Fouled spark plugs.
I like to replace my motorcycle spark plugs every year at its service interval. They are a cheap part that if replaced regularly will help your motorcycle start at the first crank.
Make sure to folliow the spark plug instructions to gap the electrode and how to tighten them down.
Can you tighten spark plugs without a torque wrench?
Yes, you can tighten spark plugs without a torque wrench if you follow the manufacturer’s instructions. Often this will be to hand tighten the spark plug and then use a socket to tighten the spark plug an additional 1/2 to 2/3 turn for new plugs with a gasket.
6. Ignition coil or leads shorting down to earth.
Check over the ignition coil and spark plug leads once a year. These can break down over time and fail. If you notice any swelling of the ignition coils or cracks in the spark plug leads replace the leads.
Moisture inside the ignition coil or the spark plug leads can casue a short to earth due to the high voltages involved.
7. Kill switch
Some older motorcycles kill switch are wired to ground. This then stops the engine spark when it is pressed. If it is shorted to ground in some models you can still crank over the motorcycle but it will not start.
Clean the kill switch and check for continuity according to the electrical diagrams for your motorcycle.
Most modern motorcycles have a all in one stop/start ignition switch which prevents starting of the engine in the off position.
8. Fuel Pump
With new fuel-injected motorcycles, a high-pressure fuel pump is needed to pressure up the fuel rails. Without enough pressure, the motorcycle injectors will not atomize the fuel correctly.
This is a classic reason why your motorcycle won’t start but turns over. An easy way to check is to listen for the fuel pump priming once you turn on the ignition switch. It should only take 2 or 3 seconds to prime up the fuel rails.
If the fuel rail cant prime up to pressure you could have a leak or a faulty fuel pump. A fault code could be listed on the ECU. You can use car Bluetooth OBD II readers for motorcycles to check any fault codes. Sometimes you will need an adaptor cable just like this Yamaha 4-pin to OBD2 cable.
9. Blown head gasket
If your motorcycle head gasket is blown you could have coolant leaking into the cylinder. Water and fuel don’t go well together so your motorcycle will not start or will run rough. A quick check is to see if the coolant reservoir is going down after a few days of use.
You could also have lower compression on the cylinder that has a hole in the head gasket making it harder to start.
I have successfully repaired coolant leaking from the engine block head gasket by using a product called K-Seal. This was on a Ford Focus car but the product works well on motorcycles as well.
10. Starter relay
Motorcycles have relays that operate the starter motor. Over time these relays can fail or the contacts can become worn and pitted. This creates a hot joint that won’t allow 12v to the starter motor. The good news is that these relays are easy to replace.
Look for the fuse box area as these relays will be located there. If you are hearing a clicking sound when trying to start your motorcycle you usually have a faulty battery.
The low battery level is enough to activate the starter relay but not turn over the motorcycle.
If you dont hear a clicking sound you most probably have a faulty starter relay.
Motorcycle not turning over fix.
If your motorcycle is not even turning over then check the following possible problems.
- Side stand is down with the motorcycle in gear.
- Clutch position switch
- Kickstand position switch
- Gear position switch
- Engine fault codes
- Battery and terminals
- Throttle position switch
- Engine stop switch
- Engine start switch
- Low engine oil level
Any one of the above issues can cause your motorcycle to not start. Often it is a faulty switch like the kickstand switch that gets covered in road dirt.
Motorcycle wiring diagram explained
The above wiring diagram shows a basic motorcycle start electrical circuit.
If you turn on the ignition switch and the fuses are ok power will flow from the battery through to the control module labeled No 13. If you then press the start button power will activate the starter relay provided that the side stand, clutch switch, stop switch, and gear position sensor are not active.
The alternator will charge the battery with over 13v while the motorcycle is running.
The rectifier regulator will change the alternating current to a direct DC current that will be fixed at around 13 volts no matter what the engine speed is.
Fuses protect the wiring and instruments if there is a fault in the system.
There are many more wiring diagrams for a motorcycle such as the lights, indicators, and fuel injection systems. But I thought I would just explain how the motorcycle start wiring diagram works.
Make sure to slowly work through the above steps if your motorcycle won’t start but turns over. It is a simple process of elimination, spark, fuel, and oxygen. If any are missing you will have problems starting your motorbike.
Try and locate a workshop manual for your motorcycle it will help you with basic mainterance and fault finding.
Keep up with the regular service intervals for your bike and you will have trouble free operation for years to come.
I am a qualified Industrial Electrician for the past 20 years and I love to share my knowledge on home repair jobs.
I love fast toys like Motorcycles, Cars, Jetskis, and Boats so writing about them is easy.
To keeps costs down I do all my own mods, repairs, and servicing. These skills I want to share with everyone. DIY is a skill everyone can learn.