What is special about a CDI?
CDI stands for capacitor discharging ignition, in which a capacitor is charged to a high DC voltage (up to 500 V) and, when it is ignited, transfers its stored energy to the spark plug via an ignition coil, whereby the ignition coil once again steps up the voltage. A CDI ignition coil differs constructively from ignition coils of other ignition systems because it acts only as a transformer and not as an additional energy store. To charge the ignition capacitor, either a special winding of the alternator is used (AC-CDI) or a voltage transformer is integrated in the CDI (DC-CDI). Like all ignition systems, the CDI needs information about the position of the crankshaft in order to trigger the ignition at the right time or crankshaft angle in front of the top dead center. This is often supplied by a pick-up type inductive encoder, which emits a signal at each crankshaft revolution. With the four-stroke engine, every second triggered ignition is therefore superfluous, as the exhaust gas is also ignited. If side stand monitoring is integrated, the ignition is switched off when the stand is folded out and a gear engaged. The advantage of a CDI ignition system is that it works well even at very high speeds. Compared to other ignition systems, the relatively short burning time of the ignition spark can be disadvantageous.
What is special about a digital CDI?
Our digital ignition boxes are DC-CDIs with components that were not available when the original CDIs were developed: A complex circuit with an IC specially developed for this purpose protects the electronics against overvoltages on the on-board power supply. If a certain amount and duration is not exceeded, it continues to work normally. If the stress becomes too great, e.g. in the case of a defective on-board voltage regulator, it switches itself off briefly, then on again, until the overvoltage has dropped to a tolerable level. In contrast, analog CDIs can be destroyed permanently in such a case. The normally used thyristors, which connect the ignition capacitors to the ignition coil to trigger the ignition, were replaced by an IGBT, the bipolar transistor of the voltage converter by an FET with correspondingly low switching losses.
All functions of the CDI are controlled by a microcontroller. This makes it possible to influence the voltage converter for the ignition voltage depending on the speed. This way, a high degree of efficiency is achieved and the ignition capacitors (two per Transalp CDI) are fully charged even at maximum speed. If the voltage of the battery is very low, it is protected by a moderate reduction of the ignition voltage and is not further burdened by an increased current. The greatest advantage of the controller, however, is its flexibility in generating the ignition map, which has a decisive influence on many engine characteristics: power, torque, temperature, starting and idling characteristics, fuel consumption, knocking, exhaust gas and even acoustics. Until today, the ignition map was fixed by using analog components. We offer two versions of our CDIs:
- The dual-line version comes with two preconfigured ignition maps: The legacy ignition map that is identical to that of the original Honda CDIs and an advanced ignition map with more advanced ignitions in medium speed range. By changing a jumper on the CDI, you can select which one you want to use. This configuration can be reversed at any time. Within Europe, we recommend using the advanced ignition map that is optimized for today's fuel quality. The legacy ignition map may be used when traveling abroad somewhere where only fuel with a lower octane count is available (e.g. during an Africa trip). The dual-line version is the "plug & play" version and therefore the recommended choice for normal motorcyclists: just install it and you're done.
- In the programmable version, the ignition map can be freely adjusted in a predefined range using our software CDI Tuner. It can be defined individually by entering support points in a table or graphically using drag & drop. Other parameters can also be changed. The programmable version is designed for tuners and technically interested motorcyclist who are familiar with the subject matter and know what they are doing. Our programmable CDIs can also be made compatible with other motorcycles than those supported so far, preferably in cooperation with us.
Because we are constantly looking for small improvements, all new CDIs are equipped with a light-emitting diode (LED) near the connector. This is an easy way to detect or eliminate faults in the ignition system if the engine does not start. If the engine runs at a certain speed and the LEDs flash, the fault cannot be caused by the ignition. If both LEDs remain dark, the CDIs have no power supply (check the fuses, ignition switch, kill switch, plugs, etc.). If only one LED remains dark, it is possible that the corresponding pulse generator does not provide a signal.
How does programming the CDIs work, e.g. for the Transalp PD06 and Africa Twin RD03?
Instead of moving a jumper, as with the dual-line version of our CDIs, a converter is plugged into the programmable CDIs and connected to the computer via a USB cable. The CDI also receives the power supply necessary for programming via the cable. Initially, the drivers for the converter have to be installed once on the computer and our software CDI Tuner has to be downloaded. Further information can be found here.
How do the jumpers have to be set on the dual-line or programmable CDI?
1) A jumper must always be inserted between the lowest two pins of the upper 5-pin socket connector. It ensures that the microcontroller functions correctly in the event of electromagnetic interference. With the programmable CDI, no other jumpers are required apart from this jumper.
2) In the dual-line version, the second jumper is used to select the ignition map as described here. In the current firmware, this is queried once when the ignition is switched on. With the programmable CDI, this jumper is omitted. Instead, a converter (6 pins) is inserted here for programming.
Can the CDI be reconfigured during operation?
With the dual-line version, this is not possible. Here, the ignition map is switched by moving a jumper on the CDI. The position of the jumper is read out once when the engine is started. Therefore, the engine must be restarted for the change to take effect.
The programmable version can be reprogrammed during operation. This is useful, for example, for measurements on the test bench or with a stroboscope.
Is there a way to switch the ignition map of the dual-line CDI via an external switch?
Yes, this is possible. Unfortunately, we currently have no switches in our range. However, you can easily build such a switch yourself (see picture).
Note: The activated ignition map is read out once when starting the engine. Therefore, activating the switch while driving does not bring any change. The engine must be restarted for the change to take effect.
Is it possible to use the digital CDI together with an analog CDI in the Transalp PD06 and the Africa Twin RD03?
Yes, it is possible to operate an analogue ignition box together with a digital ignition box without any problems.
Are there measurement results that show the difference (power, torque) between the legacy and advanced ignition map curves?
Unfortunately, we do not have any such measurements at the moment. However, there is already a lot of positive feedback from Transalp drivers, so there is no doubt about the better performance with the advanced curve. The Africa Twin RD04/RD07 drivers also report that they are very satisfied with our digital CDI.
Why are the case dimensions slightly different from the standard?
The outer dimensions are historically determined. However, our CDIs fit fine into the CDI pockets.
Is it really that important to install interference suppressed spark plugs when using digital CDIs?
Yes, the Honda Transalp manual also says that candles with a built-in resistor must always be used. Electromagnetic interferences should always be kept low as they have a negative effect on nearby electronics.
Can the user add new motorcycle types to the software of the programmable CDI him-/herself?
The design characteristics of the pulse generator (inductive encoder) are different for each motor type. Therefore, the speed-dependent signal is measured especially for our CDI. This measurement is a prerequisite for the accuracy of the ignition map output. Unfortunately, it is not possible for the user to carry out this measurement him-/herself. An alternative is to simply select a similar type of motorcycle with respect to the desired parameters (there are preset ignition maps for all motorcycles listed on the start page and some more). In this case, however, the actual ignition curve deviates to a greater or lesser extent from the desired programming and should always be checked.
It is better if you simply contact us. Maybe there's a way to get in touch and measure the bike.
Can the double CDI also be used in the RD07A? How does the RD07A differ from the RD07?
Unfortunately we do not have a special CDI for the RD07A in our offer. The RD07A is the successor of the RD07 and uses a different CDI which is not directly compatible with ours. The best way to check compatibility is to find out the name of the original CDI. Our ignition box replaces the CDI with the name CI-600 (on the right side of the picture).
In principle, it is possible to use our programmable CDI in the RD07A. However, this involves a few modifications and a certain amount of work, which we unfortunately cannot take off the riders' hands. In our experience, this is generally not economical. If you are interested, we will of course be happy to go into detail.
Is it possible to use the CDIs for motorcycles with Hall sensor as pulse generator?
Yes, that is possible. Since these sensors switch before OT independent of speed at a fixed angle, it is even possible for the user to set the parameters of the pulse encoder himself. To do this, select the motorcycle type HALL-Sensor pick-up (unipolar) in our software CDI Tuner and indicate at which reference angle the sensor is to switch before OT and whether the positive or negative edge is the reference. The sensor should have a high level of approx. +12V and a low level of 0V. The magnet must be temperature-resistant and positioned on the polar wheel so that the HALL sensor switches at the desired maximum early ignition angle.
Even better is a bipolar HALL sensor system with a second magnet. The second magnet is mounted on the polar wheel with reversed polarity in such a way that it determines the ignition angle at low speeds until the start of the early adjustment. Such a system is necessary for motors, which are set to only a few revolutions and low speed when they are kicked. For this you need a HALL sensor bipolar latch, e. g. the TLE 4935. A suitable profile in our software is for example the Yamaha SR500. We recommend you to contact us.
Is it difficult to use programmable CDIs in other motorcycles?
If this type of motorcycle has similarities to the Honda Transalp (perhaps only a different connector system as with the XLV750R), then it is sufficient to connect the 12V on-board power supply, the ignition coil (s), the pulse generator and possibly the side stand monitoring (if necessary via a plug adapter). The Transalp motorcycle profile (possibly with adapted ignition voltage and side-stand monitoring logic) can then be used for the CDI calibration. It is then recommended to stroboscope the ignition timing. Via the parameter sensor advance, the ignition map can be shifted to achieve a more or less exact result if the pulse generator is similar to that of the Transalp. If this is not the case, there are several other motorcycle types to choose from that can be used as a template.
It becomes more complex if the pulse generator delivers a substantially different signal than the available originals and even an adjustment of the sensor advance does not produce a satisfactory result. Then you cannot avoid measuring the pulse generator yourself. The difficulty here is that with an inductive encoder, the output voltage is speed-dependent and therefore the crankshaft angle at which a connected voltage comparator switches shifts more or less speed-dependently. In order to obtain accurate results, this effect must be taken into account. All programmable CDIs universally have this problem, but it is not always so clearly emphasized. As a result, the actual ignition angle adjustment can deviate greatly from the supposedly programmed one. Or the voltage of the pulse encoder signal may be unusually high or low. In the first case, it would be possible that even the "sediment" of the pulse encoder voltage triggers the input circuit of the CDI, then of course at wrong times. Here the output voltage can be attenuated with an intermediate voltage divider. Otherwise, you will not be able to avoid adjusting the switching threshold of the CDI yourself.
Extremely precise ignition maps are obtained with low effort and with sensors that deliver a digital signal at a constant crankshaft angle regardless of the speed (e. g. Hall sensors). We can only recommend such a system for motorcycles that only reach very low speeds when starting (single cylinder with kickstarter). We tried to retrofit a Yamaha SR500 with it and were amazed at how far down the idle speed can be decreased with it.
Older motorcycle models such as the SR500 can have very exotic ignition systems. In individual cases, it only helps to check what needs to be changed or can be used further, e.g:
- Is there a suitable encoder system for the crankshaft angle?
- Is the ignition coil a CDI type in normal design or a special type (e. g. with diode)?
- Does the vehicle on-board power supply system have a reasonably stable 12V system?
- Does the ignition switch have a contact that outputs 12V when switched on?
- Is there enough space and a mounting option for the CDI?
Is it possible to get CDIs for special applications?
We are happy to do this in cooperation with our customers. We can equip our CDIs with new firmware at any time. In the Yamaha SR500 we have tried to change the triggering of the ignition in such a way that the "wrong" ignitions are suppressed. This enabled some carburetor settings to be made which, according to customers, had a very positive effect.
Another application was mopeds with speed limitation. The usual measures in the intake tract or exhaust pipe mean that you hardly ever get up a mountain, but then downhill the permitted speed is easily exceeded. With some Skymax ST50 with gear recognition we have implemented the speed limitation via the ignition (adjustment of the ignition timing after late). The result in comparison to the usual throttling: Full engine power up to the permitted speed, then clear limitation.
Is it even permitted to install a CDI other than the original in road traffic?
For Germany, we have the information from the Federal Motor Transport Authority (KBA) that original parts can be reproduced if they do not have a certification mark. We do not have any information on this for other countries.
Do you also repair original CDIs?
It's just not worth it. The ignition box would need to be opened carefully and all solder joints should be uncovered without damaging the circuit board. For long-term success, it is recommended to remove old soldering tin, increase the size of the pads by scraping off the solder resist and then re-solder everything. Possibly the box will work again. However, it could also be that not only the solder joints but also components have suffered from the ravages of time (e.g. ageing of electrolytic capacitors and diffusion processes in ICs). The consequences can be bad starting behavior, faulty ignition adjustment and misfire. The effort is enormous and the result is difficult to predict.