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Disclaimer:

1.  Let me first start with the fact that I am NOT a mechanic.  I have been working on motorcycles and scooters for a long time and know a little about what I am doing.  I simply take pictures for other people to use as a guideline to help them modify their own motors.  Any modifications you perform are done completely at your own risk and liability.

2.  Tampering with your motor in any way may void your warranty.  Make sure this is a sacrifice you are willing to make before you begin working on your own vehicle.

3.  Before you begin, read this ENTIRE article from start to finish so you know exactly what is involved and what steps are required to properly complete the procedure.  Also make sure you have a nice clean area to work in.

4.  This example was performed on a 2006 Sachs MadAss 50cc automatic.

5.  ALL bolts and socket head cap screws are in metric! Don't try to work on your vehicle if you don't have metric tools, you will just wind up messing up the heads.

 
Well, if you own a Madass and plan on doing any sort of motor modifications, chances are you will some day be swapping your stator for an after market unit.  Swapping the stator is fairly simple, but requires some time and a few specialized tools.
 
What is a stator, what does it do and why would I want to change it? 
A stator in simplest terms is a motorcycles alternator so to speak.  It generates the power to run accessories like lights, horn and charge your battery for ignition.  But where it differs from an alternator is that it also generates your ignition spark for your engine to run.

There are several different stators available: inner rotors, outer rotors, 2 phase, 3 phase, ect.  The inner rotor type is usually only used in a high performance application.  The inner rotor type mounts the magnets on the inside of the coils and spins inside the coil.  While an outer rotor spins a large bell housing containing the magnets on the outside of the coils.  The pros and cons are simple.  The inner rotor has a smaller amount of mass to turn since it is designed to mount and spin inside the coils.  The main advantage of this is that the motor will build RPMs much faster verses an outer rotor where the motor has to rotate a large heavy bell housing around the outside of the coils.  The downfall to this is that surface area of the magnets are greatly decreased and the amount of power generated is also greatly decreased.  This is why the inner rotor is generally used in high performance applications like Motocross bikes and such.  The inner rotor type simply doesn't produce enough power to run a headlight, tail-light, horn and keep a battery charged.  They simply generate the power needed to run the ignition and give the vehicle its spark.
 
So how do we change the stator?  Well, lets show you how.
First you need to drain the oil from the motor.  The stator is mounted on a plate that seals the side of your casing.  If you remove the stator plate without draining the oil, you are going to have a BIG mess to clean up.
 
Remove the side cover located on the same side as your chain.
Use and impact driver and remove the nut holding the bell housing onto the crank.
 
Use a puller to remove the bell housing.  Here is a picture of what they look like.  the left one is a 19mm puller and the right one is a 21mm puller.  The one on this bike is a 21mm X 1mm pitch - Left Handed threads
 
Screw the puller onto the bell housing.  Thread it down as far as you can.  Then screw the center bolt into the puller until it makes contact with the crank shaft.  Hold the puller with a wrench on the 2 flats and tighten the bolt up until the bell housing comes loose.
 
Once the bell housing is off, you will need an impact screwdriver similar to the one shown below to remove the stator plate.

Use the impact screwdriver to remove the 2 Phillips head screws holding the stator plate on.
 
Pull the stator plate off and expose the inside of the motor.  Be certain not to lose the o-rings that go behind the screws.
 
This is our new stator plate that we are installing along with the new higher output rectifier.
 
Push the new stator plate onto the crank shaft.  Line up the screw holes and gently press the plate in until it bottoms out on the o-rings.  Replace the 2 Phillips head screws and use the impact screwdriver to tighten them up good and tight.

When mounting the new plate, I like to remove the green wire from the harness coming from the stator.  The green wire is your ground wire.  You can run it up over the motor and attach it to the harness up above where the stock wire was attached, but that simply goes and bolts to the motor somewhere else.  I like to attach it here at the motor inside the cover.  So I remove the clasp holding the wires as shown below and pull the gree wire out of the wire loom.
 
Then I cut the wire to length and terminate a ring terminal onto the end of the wire.  Then I find a screw hole nearby and attach the terminal and wire to the motor.  Be certain to use a hole that is clear of the cover.
 
Once that is done, simply line up the key on the crank shaft and replace the bell housing.  Use an impact driver and tighten the nut up onto the crank shaft.
 
That is pretty much it.  Don't forget to put oil in the bike before you run the motor.  If you find you need help wiring up your new stator, be sure to visit our Madass Wiring Guide.

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