I've been finding that an alarming amount of people are having trouble with bikes that won’t start and most of the threads consist of "My bike won’t start, help". It's extremely difficult to troubleshoot a bike with that little bit of info, but if you follow this guide, you can likely find the problem on your own, or at least get enough info to help us help you.
There are a number of things that can prevent a bike from starting. Almost all of them are electrical. Your first step will be to grab a manual. You will need it to complete the following troubleshooting steps. Your next step should be to develop a systematic approach to your troubleshooting and use known tests (service manual) to rule out possibilities. If you just start shooting in the dark, you may get lucky, but you may never find the answer. I’ve provided ways to test with and without special tools, in many instances here but to do things properly you will need to get a few things.
-Digital Multimeter, capable of testing resistance, voltage and continuity.
-Test wires w/alligator clips.
This one should be obvious, but your headlights should come on, gauge cluster lights up and POSTs. If you find that none of these things happen, check your fuses. If your headlight fuse is either absent or blown, your bike won’t start. Charge/replace your battery. If you have a multimeter available test your battery for 12v. If it’s low, charge it. If its 0, replace.
2. Fuel Pump and Kill Switch
Is your kill switch set to the "RUN" (down) position? Turn the bike on and flip the switch off/on. You should hear your fuel pump prime. If you do, your kill switch works. Make sure to leave it in the "RUN" position for the rest of this guide. As soon as you turn your key to the "ON" position your fuel pump will make a short 3s whining sound if the kill switch is "on". This is your pump "priming" and sending fuel to your injectors. If this doesn't happen bypass your kill switch by disconnecting the white 7-pin connector on the right side of the bike near the frame (next to the red 2-pin connector). Using a piece of wire and two small alligator clips jump the pins for the White/Black & Black wires on the bike side of the connector (not the switch side). This will bypass your kill switch and should engage your fuel pump as long as your key is in the "ON" position.
If your fuel pump still doesn't prime, test your fuel pump relay (video below) and bench test your fuel pump. To do this, using two wires with alligator clips on both sides connect one to each of the pins inside of the brown connector on the bottom of the fuel pump. Green is ground, Brown is positive. Connect the green to the negative terminal on your battery (known good 12v power source), Brown to the positive terminal. Your fuel pump should prime. If it does not, replace. It's best to do this with the main fuel line coming from the fuel pump disconnected on the injector side and routed into a small container. Once the pump primes you should see a strong steady stream of fuel. If you do not, replace.
Note: Do NOT touch the two clips to each other, they will spark, and spark/fuel does not mix. This test is easiest when you have two people, with the fuel tank and battery removed from the bike completely.
3. Switches and Sensors
Okay, so your kill switch and fuel pump work fine but your bike still won’t start… what now? Your Bank Angle Sensor (BAS), Neutral Position Indicator and Kickstand sensor can all prevent your bike from starting.
To bypass your BAS
remove the sensor located underneath your 3rd Eye Headlight and using a wire with alligator clips on each side, connect one clip to the pin for the green wire and the other to the Red/Blue wire on the harness side of the sensor.
Next you’ll need to disconnect your kickstand sensor. The connection can be found by tracing the harness going to your kick stand. All you need to do is disconnect it.
And your Neutral Position Indicator sensor will need to be tested using the method shown in the attached picture.
Once all 3 sensors are bypassed/tested, try to start the bike. Make sure you’re in neutral when you do this. If your bike starts, it’s all a matter of the process of elimination. Put each sensor back 1 at a time and try to start the bike after. When it fails, you know what your problem is. Replace.
4 Ignition, Fuel & Compression
Okay, still wont start? Now what…
There are three things required to make a motor run. Ignition (spark), Fueling and compression. We’ve already done a majority of the testing for fueling in step 2 so we will bypass that for now. Its still possible that your injectors are clogged, but I’ve never seen it happen.
To test ignition, remove each spark plug and visually inspect the electrode. If it’s wet, you fouled your plug and it will need to be replaced. One spark plug at a time, Connect the ignition coil (boot) to the plug and hold the grounding stripe to the frame and attempt to start your bike. Make sure you’re holding the very top of the boot and no part of your (gloved) hand is touching the spark plug itself. Your plug should immediately spark multiple times to the stripe. Hold the starter for about 1-3 seconds each so that you can make sure you get good spark. If you don’t get spark on any particular spark plug, try swapping out the ignition coil with the coil from a different cylinder. You can see where I’m going with this. Replace the ones that need it. If you don’t get spark from any coil, make sure your kill switch is still in the run position and make sure each of your main wiring harness connections for the coils and the primary harness connection are nice and clean/tight.
I like to test compression as I test spark for each cylinder. It’s easier not having to R&R spark plugs multiple times. A compression tester is $20 from Harbor Freight. Keep in mind this is a very cheaply built tester and the design is poor. This style tester has the check valve at the gauge instead at the end of a pressurized hose. Because of this design, the tester will add volume to the cylinder which means your readings will be significantly lower than what’s indicated in the manual. The manual indicates 178psi for each cylinder. These test kits will usually indicate around 120psi. To test compression, thread the tester into the plug hole using the appropriate adapter, hold the throttle at WOT and attempt to start the bike. Give it a chance to turn over a few times to build compression, and you should see the values on the gauge go up. Once it steadies up (usually around 3 complete cycles) you should have your results. You're looking for around a 10% uniformity between each of the cylinders. If your results are significantly below the expected values, take your bike to a shop, you will need motor work. Most likely a blown head gasket or piston rings. If you've gotten to this point, you've likely already seen issues with the bike overheating, losing coolant or other temperature related problems.
That should pretty much cover like 90% of all of the “My bike won’t start threads”. Questions or comments, let me know. Or if I missed anything.
Note: for some of the electrical connections (the female ones) you will need to use a small probe or solid copper wire stripped on each end to bridge the connection.
Always use insulated tools and a gloved have when touching wires.