Ofapars.

This is how i rewound the stator (alternator) on my CX.

The pics and text here relate to the transistorized ignition type CX`s, not the CDI equipped early models. The stator on the TI bikes only handle the charging of the battery unlike the CDI type which also provide power to drive the ignition `black box`,  and are more complex in having two additional coils integral to the stator made up of much finer wire with many more turns. It`s these coils which seem to have more potential for a breakdown/failure and are the main reason for problems on those stators. If i had a CDI type CX and was having ignition issues i`d convert it to the newly available Ignitech option at the earliest opportunity which should provide much more reliability and ignition performance.

If you suspect that your stator is failing the first sign would probably be difficulty with starting: a flat battery. There are two or three easy checks you can do to identify whether or not the problem is with the stator.

First do a battery voltage check: set your multimeter (MM) to measure DC volts and put it accross the battery terminals - with the engine running at tickover speeds i usually get somewhere between 14.3 - 14.4 V. Increasing the engine speed to 5000rpm the voltage may increase slightly to 14.5 and ideally should not go any higher than this. If you get anything in the region of 12.X for example it suggests that either the stator has failed or there may be a wiring defect in the charging circuit.

Incidently, if you ever see a charging voltage which is creeping towards 15V it is a sign that the regulator side of the reg/rec unit  is `seeing` a lower battery voltage than it actually is and over-compensating. This is due to small voltage losses in the 25+ year old wiring loom because of small resistances/voltage drops in the various multiplugs and ignition switch in the voltage-sensing circuit. A battery receiving a charging voltage of 14.9, say, or upwards will have a tendancy to evaporate the electrolyte more readily and could result in low levels in the battery if left unchecked. Half a volt or so doesn`t sound much but it can make a difference to the health of your battery. There is a quick fix to cure this: find the 5-wire multiplug that connects the reg/rec to the main wiring harness (on the `electrical plate` next to the battery) and remove the smaller-gauge black wire from the connector (by depressing the locating tang and pulling it out) on the reg/rec side of the connector. Make up a small fly-lead with an insulated spade on one end and an eyelet on the other. Connect the spade to the black wire and then the eyelet is bolted straight onto the battery +ve post. This lets the reg/rec see voltage straight off the battery with no losses due to the resistances of an old, tired wiring loom. The charging voltage of the battery should now come down to the ideal range of 14.3 - 14.5. Having the reg/rec permanently connected like this will draw a tiny current from the battery to power the voltage sensing circuit of the reg/rec but i have found that the battery drain is so small that even after my bikes have been stood for weeks they still have enough ooomphh to provide cranking power. The current drain is probably similar to having a digital clock in your fairing - miniscule. If you ever see a charging voltage of say, 16 volts or over this is probably a FUBAR reg/rec and this sense-wire detour will not cure it - unless the black sense wire has become open circuit somewhere. Another good piece of charging system `housekeeping` is to ensure the main wiring loom earth point is positively attatched to the frame; you`ll find this on Euro`s and GL650`s under the seat/above the airbox - it`s the green wires crimped to an eyelet. On GL500`s there`s also one under the tank located on the l/h side coil mounting bolt. Undo, clean both parts to good, clean metal and resucure.

Back to stator testing....

Locate the cable that comes from the rear engine case and connects the three yellow phase wires to the multiplug of the regulator/rectifier - the connector is located on the `electrical plate` to the side of the battery on Eurosports and GL`s . If you`ve seen a low voltage accross the battery in the first test you might be lucky and have a simple repair; this connector is prone to being burnt/melted/damaged - there`s a high load on the terminals of this connector and its not unheard of for them to develop high-resistances and overheat enough to melt the plastic.

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 If it is damaged simply cut the connector out and re-make the joins using a suitable connection method: crimped spades/soldered joins etc or a replacement three-way connector block from Honda if you want to keep it original! Any method is good as long as the joins are 100% secure and well insulated. The three yellow wires can be connected to any of the other corresponding three wires going to the reg/rec - it doesn`t matter which way they are hooked up.

If the connector appears good then the next thing to do is check the phases and insulation;

Set your MM to a low resistance range, say 0-200 Ohms. Unplug the 3-way connector to isolate the stator. Note the three terminals in the connector block,call them 1,2,&3. Test the resistance of the three phases by putting the MM accross terminals 1&2,1&3 and 2&3. You`re only measuring about 24 meters of high-conductivity thick`ish copper wire so on a good stator there should be very little resistance, expect a reading of about 1 Ohm or slightly less in each case. A high resistance may indicate a partial break in the phase or poor connection on the stator output wires. FUBAR. An open circuit on any of the checks is of course bad. Because the phases are joined together this test won`t actually tell you whether you have a short between them or if any of the individual coils have shorted to another or any other part of the stators windings, so you can also check the AC output of each phase by running the engine with the three-way multiplug disconnected and check the voltage between terminal 1&2,1&3 and 2&3 again. Set your MM to ACV. Be careful not to short out the terminals of the connector with the probes of the MM. Expect about 25 - 30V AC at idle speed, and it rises rapidly to 50V+ when engine speed increases. The actual voltage will vary from bike to bike depending on various factors according to each individual stator, but the thing to look for is that all the measured voltages on the three phases should be very close to each other, one reading lower than the others by say, 20% or so may indicate one of the phases has an internal short in a coil.

This stator required the AC test to pinpoint the fault: on the continuity tests there was no evidence of any fault to earth and each phase had good, low restiances between each phase of less than one ohm (this was probably the restistance of the meters` test leads) so ostensibly it checked out OK, but with the engine running the battery voltage was less than 12V and would drop even further until the voltage was so low that the ignition system started to go unstable and the engine would start to falter. The AC tests showed an output of less than three volts on two phases, and zero on the other...  When the engine was removed and the stator examined this was found - the final output wires had fried themselves and shorted out;

(clickable images)

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The most common cause of failure on these stators is a short to earth/ground. Unplug the 3-way connector to isolate the stator and set your MM to measure resistance. Connect one probe to a good engine earth point and the other to each of the connector block terminals: you should have very high resistance -  megohms - no reading on the MM - open circuit. If your digital multimeter`s reading indicates that there is continuity to earth then the stator needs replacing.

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I have three Honda CX Eurosports on the road (or complete...),and another CX-based project bike on the go,so i am preparing a spare alternator ready to fit in case of failure.
This one is from my spares pile,and although checks out OK with a meter,does not look like it could be trusted due to it being knocked about/damaged while in storage.
It has also been re-wound previously as you can see - the resin coating the windings  that Honda finished their alternators with is not present on this one.
I rewound one myself a number of years ago and it provided many years and thousands of miles service before i took the bike off the road,so i know that this job is`do-able`,and now that i have found a supplier of epoxy resin to coat the finished windings the job should look more professional this time,too..
If you send a stator to a rewinder,this is the way they are done - by hand,so why pay some one to do it when its possible to do it yourself?
If you are feeling brave,have the necessary patience and are nimble-fingered enough it`s a very straight-forward job,just a little bit fiddly,but if you get it wrong,it`s an engine out job again on a CX.
What can go wrong?
Short circuits.The copper wire is insulated with a thin coating of polyurethane (or other) varnish,it`s tough and heat resistant,but will not tolerate sharp edges which could break the coating and lead to the alternator windings making an electrical circuit to earth or to each other within the same coil,or vibration between the windings which would erode the varnish.In either case the stator would be faulty.The coils have to be wound snug enough to be secure without movement,and the epoxy helps further by encapsulating the finished job holding it all in place.
Only attempt it if you have the confidence to make a good job of it,or are prepared for the consequences if things go wrong.....
This is how i did it.
This is what i started with;a previously re-wound stator,it checked out OK on the meter,but it didn`t look like it could be trusted once installed in an engine.And i don`t want to remove the engine again soon after fitting it.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Step one;strip the old windings off.
I took a note of the number of turns per bobbin,which way around the bobbin the wire is wound and the gauge of the wire,in this case 24 clockwise turns of 18swg/1.25mm* insulated copper wire.
Each of the three phases is approx 12M in length.
 
*After taking a closer look at an OEM Honda stator recently it appears that the original windings may of been made with 1mm wire.It was difficult to measure with only a small area of bare wire available to get the vernias onto,most of the windings being covered in epoxy,but from what i could tell both visually and by measuring the Honda wire was a smaller gauge.
The larger gap between one pole-piece`s windings and its neighbours also suggest that the original wire is thinner than that used for my rewinds - neighbouring windings on my rewound stators virtually touch each other,with all the space inbetween taken up:compare the two pics - mine versus OEM.
This is perfectly ok - in fact in theory it will provide more current capacity/output/wattage available to the electrical system. Think of it as a `high output` upgrade.
 
Here`s the materials i used;
18swg/1.25mm polyurethane Insulated copper wire
Epoxy potting compound
Heat-resistant wire for the final output wires
Some heatproof sleeving and binding tape.
The copper wire i used has a max. continuous operating temperature of 155 ·C which i think is plenty. The highest (oil) temperature i have seen on a CX engine is 107. If the engine temperature ever went as high as 155 the insulation properties of my stator would be the least of my worries...
No specialist tools are required,just a soldering gun,screwdriver,snips
 
The first phase has been wound....
Doing this is really hard work on your hands - don`t attempt this if you have arthritis! I can usually do three pole pieces or half an hour before my hands give up. There were a few places where the base insulation had chipped off and exposed the metal laminate - i repaired this first with some epoxy adhesive to prevent any potential problems in the winding stages;
   
 Here`s the stator after the second phase has been wound;
All three phases are now wound - thank ***k for that!
The bobbin-to-bobbin windings and the bottom join of
the phases need to be to the rear of the alternator when
installed in the engine(same side as output wires binding post),and the alternator only goes on the case one way - check....
The phases of the alternator are arranged in `star` configuration;the bottom ends
of the three windings are joined together - you can see the sleeving
where i soldered the wires together.
The `top` ends of the windings are secured with some binding tape ready for the
final output wires to be connected;
 
I`ve soldered on the three output wires with heat-resistant
wire heavy enough to cope with the current developed by
the alternator.These `permag` type alternators produce their full
power potential at any given engine speed,any `excess` power not used by the
bikes` electrical system is shunted to earth and dissapated to the air by heat via the reg/rec body - hence the cooling fins..
 
Each phase wire/output wire join was then insulated with sleeving,then another piece of sleeving over
those;this area needs to be well insulated!

It`s nearly ready for the part of this little project i have been looking forward to most:splodging on the epoxy!
Before i do that though,i inspect the windings where they go from one bobbin to the next;this area is susceptible to being damaged where it is fitted to the mounting boss on the engine rear case and shorting to earth.They are tucked out of the way and then the epoxy is mixed.
 
I was a bit concerned at first because the epoxy was taking what i thought was too long to `go off`,and i imagined i would end up with a useless gloopy mess after all my efforts and hours of painstaking toil, but the next morning it was as hard as glass and looked good.
 
It`s virtually finished here,only the final outer sleeving to be put on which includes the wiring for the nuetral indicator on these bikes and the connectors to the reg/rec wiring.The OEM multi-plug is a known trouble spot (due to the high current flow through it) and can burn up if contacts are not 100%,so i will use another more secure method at this joint.
I put it on the meter and it tested good-to-go,but the real test will of course be when it is installed in the engine,and how long it lasts...
The epoxy coating has made everything really secure and solid which should prevent any movement in the coils/windings resulting in shorts/chafing,so i see no reason why it shouldn`t be reliable for many thousands of miles,in fact i have seen rewinds where no coating has been applied.
 
This stator will be used in my CX650 when i remove the engine to replace the camchain in the near future.

The average cost of a rewound/exchange stator here is approx £75 - 80 all-in,this one cost me £18,and i thought that was high!
The price of copper has sky-rocketed over the last couple of years which bumped the price up a bit,and i bought a 500g bag of epoxy which was far too much for this job,a 250g bag would have been ample.
Of course the cost is only part of doing a repair of this sort - it`s being able to as much of your own maintainence as possible.Riding a bike with electrical power being generated by your own work is a good feeling...
***There is some useful information on the perils of stator replacement here from another CXian in the US.***
 
*update*
the stator is installed in my GL650 engine
and is putting out a healthy 14.3 - 14.5V.
I`m using heated jacket,heated grips,lights are on and it`s coping with engine starting fine.      
More stator stuff.
I`ve recently had to remove the engine from the `World Explorer` to attend to a starter clutch problem.While the engine was out i decided to do the whole lot:starter clutch,camchain,water pump seal and stator.So,i have rewound another stator,this time in a nice gloopy white colour resin.A 1000 mile round trip to Ireland on it`s very first run and later 2300 mile trip around Scotland proved it to be reliable.Which was good....
 
 
 Over the last couple of years i have stripped down quite a few engines and seen many stators with varying degrees of rewinding methods.Despite the sometimes untidy-looking winding and variance in finish they all must have worked at some point.Here`s a few pics;
 
This first one is an original-fitment from Honda; note the toffee-coloured resin(not quite covering all the windings) and neat,out-of-the -way tidy bobbin-to-bobbin windings;
   
 
 
This is the one i rewound in the top pics above(white).The windings are a little untidy/loose,but at least this enabled the varnish to penetrate right into the windings. Note that it was also wound `clockwise` around the laminate core;
 
 
 This one looked a bit rough/black/dodgy but it was working fine when i removed it from the engine.It had a slightly thinner 1mm* wire,had an additional join in the final output wires under that black insulation tape(avoid unecessary joins - potential trouble spot!) and no resin or varnish.Still worked fine,though;
*After taking a closer look at an OEM Honda stator recently it appears that the original windings may of been made with 1mm wire.It was difficult to measure with only a small area of bare wire available to get the vernias onto,most of the windings being covered in epoxy,but from what i could tell both visually and by measuring the Honda wire was a smaller gauge.
The larger gap between one pole-piece`s windings and its neighbours also suggest that the original wire is thinner than that used for my rewinds - neighbouring windings on my rewound stators virtually touch each other,with all the space inbetween taken up:compare the two pics - mine versus OEM.
This is perfectly ok - in fact in theory it will provide more current capacity/output/wattage available to the electrical system.Think of it as a `high output` upgrade.
 
 
 
This one is a complete dogs dinner!
The bobbin-to-bobbin windings and bottom phase join are on the wrong side of the stator - you can see the binding post on the other side and also note where the rotor has worn away the insulating sleeving and rubbed the wire insulation!
Amazingly,this stator was in working condition when the owner pulled the engine for camchain work.He replaced the stator.
                                              
The stripdown of a 650 engine recently revealed another stator of dubious quality! This one had exposed output wires where the insulation had perished, the mounting bolt heads had interfered with the coil windings scraping off the insulation, it was wound from the `wrong` side, and the bolts were ground down in an attempt to prevent them from touching the coils - it didn`t work;
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Another observation.
It`s sometimes said that these stators are `cooled` by engine oil. In fact, the stators receive very little in the way of an oil spray, probably getting a fine mist at best. They certainly do not get `bathed` in a full flow of the stuff. Any oil that does find it`s way inside the rotor would probably get flung out by centrifugal action anyway. The temperature inside the crankcase is probably near or at the oil temperature, too. This pic shows the result of a failed water pump seal.A fair amount of coolant found it`s way into the engine. The weep-hole must of been blocked. Notice that the whole of the inside of the rear cover is coated with the oil/water emulsion except for the stator which stands out as being distinctly mayo-free;
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So as you can see,the parameters for sucessfull rewnding techniques are wide and varied.......
 
Here`s a sketch of the winding lay-up to give you an idea of how the phases are wound in star configuration;
 
 
If you fancy having a go here`s a few tips(in no particular order);
  • the stator only fits on the case one way,check this before you start winding to get the bottom phase join and lay-up towards the rear.(away from the rotor)
  • repair any chips to the laminate core insulation before you start winding the bobbins to avoid sharp turns around the bare metal core
  • make a note/diagram of where each phase starts/ends - use the binding post and mounting bolt holes as reference points
  • use the reel the wire comes on as a `handle` to achieve a neat,snug wind,only having a few inches of free wire to give a usable working length
  • when laying down the wire impart a slight bend away from the pole-piece or previous layer - when it is then laid down it will lie flat and help achieve a neater,more compact winding.
  • i use a small plastic wedge to ease the wire into place or push it down flat if it needs a slight tweak - there`s not a lot of room left when you`re working next to another already wound pole-piece
  • be prepared to `nurse` the epoxy until it starts to go off,it`s very thin when first mixed (which aids penetration into the windings)but tends to run.Maybe wait until it gets slightly more viscous before applying?
  • obviously,when soldering the wires the polyurethane insulation has to be removed to uncover the bare copper
  • leave enough slack in the bobbin-to-bobbin wire to enable it be be moved well out of the way of where the stator fits onto the rear casing - this is a potential site for a short-to-earth (see the link above)
  • keep the areas around where the stator fits onto the rear casing and the stator fixing bolt holes free from epoxy - i removed one stator where the whole thing had been dipped in varnish and became loose in the engine because the varnish under the bolt heads (which should have been removed before installation) had  become soft due to engine heat,had softened,and caused the bolts to become loose.
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