Electronic Control Unit (ECU) failure is commonly caused by a damaged regulator. The regulator transforms AC current from the generator into a DC current to load your battery. A faulty regulator will cause the ECU to receive a voltage supply that is out of its' normal range, which will cause the ECU to fail.

How to Test the Regulator:

1. Install the replacement ECU

2. Start the engine, but DO NOT rev it up, let the engine run idle

3. Measure the battery's voltage, a normal reading will be approximately 14 volts

4. Slowly rev up the engine, while keeping a constant eye on the battery voltage. The battery voltage should stay below 15 volts

5. If your voltage reads beyone 15 volts, stop the test immediately, a new regulator is needed.

OEM electronic control units (ECUs) are commonly damaged by worn out or defective ignition coils. Although a HT coil may still spark, if the inner coils are damaged, they will continue to accept more current than the ECU can handle. This will lead to the breakdown of the electronic control unit.

How to Check the Igntion Coil: 

1. Unplug both plugs on the ignition coil

2. Measure the resistance of the two terminals. A normal reading will be between 3 and 4.3

3. If the resistance between the two terminals is lower, then your igntion coil needs to be replaced.

*Only install the replacement ECU once you are positive the ignition coils are good.

Aftermarket regulator rectifiers are not always identical to your oem regulator rectifier. There could be a difference in the amount of wires and or colors of the wires. After installing a new aftermarket regulator rectifier, and charging issues continue to persist, then you should try using the flow chart that we provide through our FAQ page. 

1. Disconnect your charging system. Put a battery charger on the battery to keep system voltage constant.

2. Use a clamp on inductive amp meter on battery negative cable.

3. Start engine. and turn on all normal electrical accessories. Read amp meter. Add 2 amps for battery draw. This is consider normal usage.

4. Turn on all accessories. Read meter. Add 2 amps for battery draw. This is maximum usage.

Please keep in mind: Amperage usage should be at least 2 amps lower then charging system output.

Visual of how to test Heat and Pickup Coils

This video should show you how to test your heat and pick up coils. This can be especially handy for hands on, visual learners!

- https://www.youtube.com/watch?v=54mNJaAleCo

You can test a Regulator Rectifiers Rectifying functionality with a multi meter, but you can not check its regulation ( typically testing for overcharging)

On a three phase charging system, you should see 3 yellow wires. Label the regulator rectifier Stator wires A, B, and C.

Label the power and the negative wire on the regulator rectifier D (power), and E (negative)  respectively.

Use the diode setting (Arrow with lines) on the multi meter. When you touch both test probes you should hear a beep. 

Test 1

D to A, B, and C  ( you should hear a beep one way on all three connections). Reverse the test probes and you should not hear the beep. 

Test 2

E to A, B, and C ( you should hear a beep one way on all three connections). Reverse the test probes and you should not hear the beep) 

Installation Precautions:

* Do NOT disconnect the voltage regulator output (the red wires), the regulator harness or the battery cables while the engine is running.

* Always remove the negative battery cable before operating on the charging system. 

*During battery installation, confirm that the negative battery cable is connected to the negative battery terminal. 

*While charging the battery, confirm that the negative battery cable is connected to the negative battery terminal (this helps avoid charging the battery backwards)

Requires very careful control of charging current and voltage - constant current with steady increase of voltage. Motorcycle charging systems have a wide range of voltage and current input completely unsuitable for Li-ion type.

Lithium-ion batteries do not accept overcharge or either excessive current when charged or continued charging when fully charged. This can result in serious damage to the battery and consequential damage to the regulator rectifier, worst case the battery can catch fire or even explode. Not suitable for trickle charging.

With many varying environmental conditions which motorcycles are used; it is worth noting that Li-ion batteries will not charge below 0^ c.

The simplest stator test would be to test the stator output at 5k RPMS.

At 5k RPMS your stator should be putting out between 50 -75 Volts* through each lead Combination.

Label each stator lead (3 wires, generally yellow) A, B, C respectively.

Test Wire combinations

A> B

B> C

A >C

If your stator is good, then you will see the same with each of the tests above.

With the engine off is to check continuity between all three legs, readings should be fairly consistent.  There should be NO continuity to ground (any three wires to engine case).

In some rare cases you will not have a spark after connecting the new ignition coil or stator. If you don't have a spark, follow these steps to solve the problem:

Check the distance between the pulse generator and the trigger tooth on the flywheel. A larger distance will cause a weak signal from the pulse generator. The distance has to be 0.5-0.6mm.

If you still have no spark, try following:

• Remove the spark plug from the bike, so there will be no compression
• Hold the spark plug to the frame of the engine, so a spark can jump over
• Put the bike in gear
• Turn the back wheel in opposite direction as if the bike would run backwards

If you see a spark:

• Solve the issue by swapping the two leads from the ignition coils (black-red and white red)

Stators are fairly simple and their problems fall in to two categories: shorts and opens. Shorts can be from winding to winding or from winding to ground AKA "Short to Ground". a) Winding to winding shorts are tested with a AC volt meter from pin to pin on stator plug with the motor running. Check service manual for proper voltage specs at given rpm. The best way to test for shorts to ground is with a 12 volt test light.Check from each stator pin to ground. If the light lights the stator is bad, there should not be any continuity from either stator pin to ground. Sometimes an ohms meter will not pick up a short to ground. The light test is the perferred testing instrument. Then Measure AC amps between stator and regulator. b) Open stators have no AC voltage output. The Shunt drop regulators draw full AC amps all the time and no e   Stators are fairly simple and their problems fall in to two categories: shorts and opens. Shorts can be from winding to winding or from winding to ground AKA "Short to Ground". a) Winding to winding shorts are tested with a AC volt meter from pin to pin on stator plug with the motor running. Check service manual for proper voltage specs at given rpm. The best way to test for shorts to ground is with a 12 volt test light.Check from each stator pin to ground. If the light lights the stator is bad, there should not be any continuity from either stator pin to ground. Sometimes an ohms meter will not pick up a short to ground. The light test is the perferred testing instrument. Then Measure AC amps between stator and regulator. b) Open stators have no AC voltage output. The Shunt drop regulators draw full AC amps all the time and no extra load is needed. Series pass regulators will be necessary to load the DC system to achieve full AC amps. Put a DC volt meter and extra loads across the battery. Add load until battery voltage drops below 13 volts with the motor above 2500 rpm. Read AC meter and compare to service manual specs. Low output indicates a stator or possibly a rotor problem. Rotor problems are rare in most motocycle with the exception on The late 1970s- early 1980s Honda CB line. It is alos possible  the magnets do get weak or become loose in some other varieties of motorcycles. xtra load is needed. Series pass regulators will be necessary to load the DC system to achieve full AC amps. Put a DC volt meter and extra loads across the battery. Add load until battery voltage drops below 13 volts with the motor above 2500 rpm. Read AC meter and compare to service manual specs. Low output indicates a stator or possibly a rotor problem. Rotor problems are rare in most motocycle with the exception on The late 1970s- early 1980s Honda CB line. It is alos possible  the magnets do get weak or become loose in some other varieties of motorcycles.

These have been used for over 100 years for automotive and motorcycle applications. Motorcycles are supplied with them from new and like the OEM regulator/rectifier was only designed to work with lead acid batteries.

NOTE: Battery capacity Ah needs matching to the output of the charging systems so do not use a car battery for any motorcycle or large motorcycle battery with low output charging system.

AC CDI Unit 
The "AC" CDI Unit obtains its voltage source solely from the alternating current ( AC)  produced by the stator. The AC CDI  Unit system is the most basic CDI system which is widely used on small engines.

DC CDI Unit:
The DC  CDI Unit is powered by the battery, and therefore an additional DC inverter is included in the CDI Unit to raise the  standard 12 VDC to 400 VDC, making the CDI Unit slightly larger. The application that uses DC CDI Unit has more accurate ignition timing and the engine can be started easier when it is cold.

AC vs DC CDI Unit
Most applications (especially the new models)  use  DC Ignitions
DC CDI Units are larger than AC CDI boxes.
The easiest way to tell if your application is AC or DC is to turn on the headlights with the machine turned off and the ignition in the "ON" position. If the headlight comes on, it is a DC application; if it does not, it is an AC application

The easiest and fastest way to determine if the charging system is operating satisfactorily is with a digital volt meter. Connect the volt meter across the battery before starting the bike. A fully charged battery should read 12.7 volts at 72degrees F. Anything less indicates a battery that needs charging or has other problems. Start the bike and allow it to run at a high idle for a minute or two to recharge the battery after starting if electrical stator was used. Turn on accessories used in normal operation (not turn signals or horn). If you get between 13.8 and 14.8 VDC (depending on model) you can assume the charging system is keeping up (as long as there is not a intermittent problem).