How to make a capacitive discharge ignition box
Content
A capacitor discharge ignition is an essential engine component of any vehicle, and by the end of this article, you will know how to build it.
The CDI box stores an electrical charge and then discharges it through the ignition coil, causing the spark plugs to release a powerful spark. This type of ignition system is commonly used for motorcycles and scooters. At home, you can build an inexpensive CDI box that is compatible with most 4-stroke engines.
If I've piqued your curiosity, wait while I explain how to make a CDI box.
Using a simple CDI block
A simple CDI box is used as a replacement for small engine ignition systems.
Ignition systems can wear out naturally over time. They can age over the years and not provide enough power to provide the needed spark. Other reasons to replace the ignition system are damaged key switches and loose wiring connections.
Our privately built CDI box is compatible with most quads and pit bikes.
The one we're about to build is known to fit most 4-stroke engines. It is compatible with pit bikes, Honda and Yamaha tricycles, and some ATVs. You can bring these old cars back to life without having to spend a lot of money on repairs.
Kits and materials for use
Building a simple capacitor discharge ignition device is an inexpensive project that requires a small number of components.
- Spark plug kit CDI coil on and off wire for 110cc, 125cc, 140cc
- DC CDI Box 4 Pin for 50cc, 70cc, 90cc
- Pulse generator with magnet (can be removed from other broken bikes)
- 12 volt battery compartment
- box or container
We recommend purchasing the specified CDI kit instead of purchasing each component individually. This is because the dimensions of the said kit and materials are guaranteed to be compatible. The kit and components can be found in hardware and online stores.
If you cannot buy a kit, then its contents are as follows:
- Switch on and off
- Spark plug
- AC DCI
- Wire harness
- Ignition coil
Steps to create a CDI box
Building a CDI box is a surprisingly simple project.
It does not require the use of tools or other fancy equipment. It is simply the process of connecting wires to the appropriate component.
Follow the guide below to build a CDI box easily and quickly.
Step 1 Connect the DC DCI to the wiring harness.
The advantage of using a kit is that it eliminates the need to redo the wired connection.
There is a port on the back of the DC DCI. Take the wire harness connection and insert it straight into the port. It should slide in easily and stay securely in place.
Step 2 - Make Wired Connections
Connecting the wires is the most difficult part of building a capacitive discharge ignition.
The image below is a simplified handwritten wiring diagram. Use the image as a reference to check that each wire is connected correctly.
Start with the blue and white striped wire at the top left corner of the DCI. Connect the other end of this wire to the pulse generator.
Then connect the appropriate wires to ground.
In total, three wires must be connected to the ground. First, it's the green wire in the lower left corner of the DCI. The second is the battery drawer wire connected to the negative terminal. Lastly, take one of the ignition coil wires and connect it to ground.
After connecting to ground, there should be only two unconnected wires.
Both remaining wires can be found on DCI. Connect the black/yellow striped wire at the top right to the ignition coil. Then connect the black and red striped wire at the bottom right corner to the positive terminal of the battery box.
Step 3: Check the CDI wire connection with a spark plug.
Check the wire connection by doing a simple magnet test.
Take a magnet and point it at the pulse generator. Move it back and forth until a spark appears on the ignition coil. Expect to hear the clicking sound that occurs when the magnet and pulser come into contact with each other. (1)
The spark may not appear immediately. Continue patiently moving the magnet over the pulse generator until a spark appears. If after a certain time there is still no spark, recheck the wire connection.
CDI is completed when the spark plug can consistently produce a powerful spark each time a magnet is hovered over it.
Step 4 - Place the Components in the Box
Once all the components are secure and functioning, it's time to pack everything up.
Carefully place the completed CDI into the container. Make sure all components are secure inside with little to no room to move, then thread the other end of the wire harness through the small hole on the side of the container.
Finally, seal the container to complete the CDI box.
What is worth noting
It is important to note that capacitive discharge ignition only provides spark to the engine.
The built-in CDI will not charge any type of battery. It will also not power lights or other electrical systems. Its main purpose is to create a spark that ignites the fuel system.
Finally, it's always a good idea to have spare materials and kits on hand.
Learning to make a CDI box is difficult for beginners. Keep spare parts nearby to minimize any delays in case of errors. It also ensures that other parts are available if one or more components are faulty.
Summing up
Motorcycle and ATV ignition system repairs can be easily done at home. (2)
Building a capacitor discharge ignition box is an inexpensive and simple project. It requires a minimum amount of materials and components, some of which can be recovered from broken bikes.
Quickly create a simple and ready to use CDI block by carefully following our guide above.
Take a look at some of our articles below.
- What to do with the ground wire if there is no ground
- How to crimp spark plug wires
- How to connect ignition coil circuit
Recommendations
(1) pulse generator - https://www.sciencedirect.com/topics/earth-and-planetary-sciences/pulse-generator
(2) ATVs - https://www.liveabout.com/the-different-types-of-atvs-4664
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