CDI controls the ATV’s ignition system, timing, and much more. As you can call it, the main brain of ATVs, bikes, three-wheelers, etc. But the engine won’t run when the spark plug doesn’t fire any sparks. That’s when you must bypass the CDI box.
To bypass the CDI box, unplug it from the socket first. Then, check the wiring resistance and test the electrical resistance using the service guideline. Examine the primary & secondary coil resistance using a multimeter.
If all are okay, there might be a problem in the CDI box. So, that’s just a glimpse of the entire process. To know the method in detail, read till the end. Let’s start!
What is a CDI Box & How Could it Fail?
Most motorcycles, ATVs, three-wheelers, specific cars, lawn motors, etc., have a CDI box. The CDI stands for capacitor discharge ignition. As for basics, capacitors work just like a battery.
It can store energy similar to batteries, but what’s the difference?
Capacitors can discharge all the energy in a flash. And that’s great for an ignition circuit. To put more, capacitors work like a trigger device.
Inside the CDI box, there is a capacitor and circuit board — that is the main brain behind all this.
So, the CDI box is the main brain behind the operation and starting your engine. If the CDI is okay, you will be riding, or you must walk. Let’s give you a quick glimpse of how CDI works.
The power source begins right from the flywheel with the stator. It sends voltage to the CDI and stores it to the capacitors.
There are diodes in the CDI that convert the AC voltage to DC. Later, it passes that to the secondary coil.
So, how does the CDI know when to send that voltage to the coil?
The pulse generator picks up the signal from the rotating magnets, and it sends back the signal to the CDI box. Then, the CDI sends the converted DC voltage to the secondary coil.
The coil then raises the voltage and passes it through the wire directly to the spark plug.
That’s how the engine starts. But how could the CDI box fail?
If the CDI box is too old, it might get damaged due to cracked soldering. However, if overvoltage passes to the CDI box, it would fry the components inside it.
Bad wiring can also be another reason. If there is a leakage in the box, water might have damaged it.
Required Tools to Bypass Chinese ATV’s CDI Box
There are a couple of things you need to bypass your Chinese ATV’s CDI box. First of all, you need to locate where the CDI box is. Basically, it resides under the seat or upper side of the engine.
As it is the main heart or brain of the engine that controls the ignition system. To bypass it, you need the following tools.
- Waterproof gloves.
- Eye safety gear.
Bypassing the CDI is important to figure out what is stopping the sparks from the spark plug.
This technique requires separating the CDI box from the connector socket and then testing each component that is responsible for ignition. And you must know how to use a multimeter properly.
How To Bypass CDI Box On Chinese ATV? (7 Steps)
Somehow, if your Chinese ATV doesn’t start, you might want to look at the spark plug. Pull the spark plug and start the engine. If you don’t see any spark on it, it’s time to check the system and bypass the CDI box.
Then, you can check all the electrical components attached to the CDI box. For that, you must unplug the CDI box. But before that, you must know the wire color code for the 5-pin CDI box.
- Green Wire: It’s the ground wire. It connects with the kill switch, ignition coil, and the ground.
- Red/Black Wire: Connects with source coil supply or stator.
- Black/White Wire: It gets connected with the kill switch.
- Yellow/Black Wire: This wire connects with the ignition coil.
- Blue/White Wire: Connected with the pick-up coil or pulser.
Now, you know the wire color code for the CDI box. Let’s start the bypassing process.
Step 1. Safety First
First, ensure there are no flammable materials like gasoline in the bank. As you’re testing the ignition system, a single spark in the gasoline might cause an accident.
Step 2. Unplug the CDI Box
Remove the CDI box from the socket. The CDI box mostly resides beneath the seat cover or above the upper side of the engine.
Step 3. Set the Multimeter with Proper Grounding
Take a jumper cable and attach the red-colored clamp to the positive side of the battery. Attach the other side of the clamp to the multimeter’s black-colored ground pin. Now, set the multimeter to measure the resistance in ohm.
Step 4. Check Stator Resistance
Grab the CDI connect plug and look for the red/black wire. Now, take the multimeter’s red needle pointer and stick it to the pin of the red/black wire. Take a look at the multimeter’s display.
Match the resistance with the service manual’s referred ohm for the working stator. If you see zero, then the problem is with the stator.
Step 5. Check the Kill Switch
Insert that red needle into the pin of the black/white. When the kill switch is on, it’s an open circuit, and when it is off, it’s a closed circuit.
Turn on the kill switch, and you should get some resistance. Match that with the specified working resistance.
If you don’t get any ohm when the switch is on, there is an issue with the kill switch.
Step 6. Check the Ground Resistance
After checking the kill switch, it’s time to check whether the ground resistance is okay.
Stick the red needle pointer to the green pin of the plug. This will measure the resistance of the ground to the battery ground.
If the grounding is good with the chassis of the ATV, it’ll show perfect resistance. Faulty grounding won’t show anything.
Step 7. Measure the Primary and Secondary Coil’s Resistance
Now, it’s time to insert the needle pointer into the black/yellow wire pin to check the primary coil resistance. Match it with the manufacturer’s given resistance.
Now, check the secondary coil resistance by unplugging the spark plug from the coil’s black wire socket. Insert the needle pointer into the socket and match the measured resistance from the spec sheet.
If both coil’s resistance are out of the list, the coil is the faulty one. You need to change it.
Step 8. Check the Pulse Generator Resistance
Get back to the CDI connecting socket plug. Look for the blue/white wire and insert the needle connector into that pin.
Match its resistance from manufacturers’ ohm resistance list for that. If the resistance is matched, the pulse generator is working fine.
From the above testing, if all components tested okay, along with a good spark plug. Then, why the spark plug isn’t firing sparks?
In that case, the main culprit will be the CDI box. To bring the ATV back to running condition, you must replace the CDI box with a new, similar spec-based one.
So, these are quick steps to bypass your Chinese ATV CDI box. Moreover, there are a couple of things that you might want to know. So, take a tool at the questions below.
How Can I test the ATV CDI box?
Take a multimeter and the CDI box. Place the black needle connector and touch any of the CDI connection pins. Now, touch other pins with the red needle connector one at a time. If the CDI box is okay, the multimeter will display various readings.
Can I replace the CDI with a different model?
You must get the exact same specification-based CDI box that comes by default. Replace with a different model; won’t work on your ATV as a result the bike won’t start either.
What are the common symptoms of a bad CDI?
If your vehicle’s CDI box gets faulty or bad, you will notice several symptoms. Among many, some are — hard starting the engine, ignition problems, stalling engine, misfires, etc.
CDI is the most important thing when discussing starting your ATV, motorbike, etc.
If this black box gets faulty, the spark plug won’t fire sparks. To avoid damaging the CDI, ensure passing the correct voltage to it.
Check the wirings for bad or torn in them. If your CDI is old and you’re having issues with it, replace it immediately. Ride safe, and have fun!