82 XJ650 Cafe Build

Basically, yes. The manual lists this spec as being tested at the connector (like you have done) and accounts for any resistance in the wire end terminals, the wires, the brushes, and the rotor windings, but, in reality, all of the other items besides the rotor windings add up to a miniscule amount of resistance, so the 4ohms reading at the rotor face will be about right (give or take a tenth of an ohm).

 

Good advice from Len as usual. You can check your harness brushes when you pull the cover. The most likely point resistance is being added is where the brushes contact the slip ring on the field coil. If you pull the cover, ohm from the connector green and brown wires to the end of the corresponding brush, you should get a really low reading of like .5 ohms or less.

Best way to evaluate the field coil would be for current. With the key on (bike not running) and approximately 10V across the field coil you should get a reading of close to 2.5 amps. I just checked mine and it is a working system and I got 2.0 amps, even though the resistance measured was 12 ohms at the connector. In theory, that would be less than 1 amp, but the 10V applied to the brushes is going to produce a different result - in my case resistance calculates to an actual value of 5 ohms.

 

Ok thanks I'll check the voltage across there as well. I actually did test resistance from where the wire connects under the cover to the end of brushes and had very low readings like you said. Now excuse my ignorance but which part exactly is the "field coil" I'm not familiar with that at all!

 

AKA - rotor

 

Ha! You learn something new everyday! Thanks for bearing with me and all the advice, it's much appreciated

 

I'm on shift today so unable to make it to the shop until tomorrow.... Is the minimum alternator brush length 8.5mm or 10mm? While testing tomorrow I just want to make sure those are good to go as well.

 

From Len's catalog:

NOTE: Alternator brushes should be replaced whenever they are less than 11mm in overall length......the factory maintenance interval indicates that you should expect to replace these brushes every 8-10,000 miles. Factory brushes have "wear marks" (scribed lines) on the brush to indicate their wear limit; these aftermarket brushes also have the scribed wear line. Overall length of these brushes are 17.10mm, with 9mm of length from the wear bars to the contact end of the brushes.

HCP215 Aftermarket ALTERNATOR BRUSHES WITH HOLDERS SET:

 

One more for you before I get to my bike tomorrow, the green and brown wires come from the alternator cover to a connection terminal, from there the green goes straight to the regulator but the brown wire goes into the harness and then comes back down from somewhere to get to the regulator. Is there another place I can trace the brown wire back to check for a corroded connection? I started cutting my harness open to trace it but decided against making a huge mess of things, and I tried reading the minimal wiring diagram but could understand the path of that brown wire. Thank you, much appreciated!

 

After reading this, you definitely have a few problems going on at the same time.
1. If your wiring harness is corroded throughout, it needs to be replaced. Think of yourself with severe arterial blockage. If the brushes are too short, the alternator will not charge properly. You'll always have problems and you'll end up chasing your tail trying to diagnose problems.
2. Also need to ensure that the stator isn't cooked or shorted to the stator body/casing. That can happen when the stator is energized or in a non-energized state.
3. Since you bypassed the stator to wiring harness connector, that's not a factor(usually is a problem).
4. If all the above is in good working order, your problem is the Regulator/rectifier.
Always follow this process: check the battery for good voltage and all the cells are good for strong amperage - check wiring/connectors for breaks or excessive corrosion - sufficient voltage at the generator input wire(B+ for the brush) - brushes are right length and not broken - rotor is good(becomes magnetized when current flows through brushes) - stator is good( not shorted or cooked) and puts out A/C volts to wiring harness connector - A/C voltage flows to Regulator/Rectifier - D/C voltage flows to battery.

Sorry if this is late in the game and comes across as Captain Obvious, I haven't been doing well lately and not been online in a while. Hopefully will be helpful to now or later or to someone else when reading this post. Hope you get it all sorted out.

 

Ok I've got my hands on it right now, just to be sure I'm doing this right, brush measurement is from the plastic where it comes out to the tip? If that's the case one brush is over 11mm but one is well under. I'm getting 4.6 ohms across my field coil rings

 

I slid the stator out and took a look in here, should the inside be dirty? Sooty, greasy type stuff, it cleans off but I didn't know if that could be causing problems?

 

Alternator Rotor:

gp2) OEM new and aftermarket re-wound Alternator ROTORS perfectly replace the originals. Rewound rotors are sold on a "core charge" basis and you must return to us a usable, same-model rotor core in order to receive your core charge refund. Re-wound rotors will output at least the same current as an original.

Checking alternator rotors: the resistance across the two lead wires (usually brown and green) at the connector should be as follows. Note that worn or damaged alternator brushes can affect these readings, as can "dirty" copper commutator rings on the rotor face (where the brushes contact the rotor):

4.0 ohms +/- 10% for all XJ650, all XJ700, all XJ750, XJ900RK, and XJ1100 models.


Looks like yours is just a bit out of spec (3.6 - 4.4 ohms would be allowable)......are you sure you ohmmeter is operating properly, and was making good contact with CLEAN commutator rings?

 

Thanks Len, I cleaned the rings good with scotch brite and they cleaned up better than they looked when I first checked them

 

Just found the plug in my headlight bucket where the ignition switch plugs in (doesn't brown wire from brushes tie in here?) is melted from corroded connectors. It's never ending haha

 

I think the length is measured end to end. I replaced the brushes on my bike with a set from Len mostly because the FSM recommendation to replace at 8,000 miles and thereafter every 10,000 miles. The originals with 18,000 miles on them measured 15mm and probably could have gone another 10,000 miles. Not sure if the FSM replacement is strictly a recommendation on wear length or brush characteristics.

A side note of this is the inner slip ring on the field coil was not smooth and showed signs of scoring. Was this caused by poor maintenance and a change in brush characteristics or is it a normal condition? Not sure of the exact process for refurbishing the slip ring, but I ended up using 2000 grit with WD40 and followed up with crocus cloth to get it as smooth as possible - still showed some scoring. I then wiped it down with isopropyl alcohol. When reassembled and the resistance measured at the connector I got a reading of 4.5 ohms, which was encouraging. Will it last, and how aggressive can you be with refurbishing the slip ring I am not sure? I have put about 500 miles on the new brushes and all seems well as far as charging. However, as noted earlier in this thread the DMM now shows a reading of 12 ohms at the connector, but the current measurement indicated a true resistance of about 5 ohms.

This old link just popped up recently where one of the members used 1000 grit and chrome polish.

http://www.xjbikes.com/forums/threads/update-help-electrical-gremlins-strike-again.27387/

Maybe some of the other member can weigh in on the best way to polish the slip rings, or if you even should attempt it. Some just recommend a pencil eraser and some have recommended the crocus cloth.

 

I used some scotch brite to clean them and wiped it down with brake cleaner since I didn't have alcohol on hand. I couldn't post the pic earlier but this was the grime on stator I mentioned, I cleaned it all off. Still got 4.6 ohms between the rings. 0.4ohm from brush tip to ring terminal for corresponding wire. Now with bike running and testing connections properly this time at regulator I'm showing 12.4v on red, 0.84v on green, and 11.8v on brown. Brown is also the brush that is below 11mm if that makes a difference. At the battery I'm getting up to 13.5 at around 5k but when I turn my headlight on it drops to 12.4 at 5k. Side note: I also checked the magnetic field test again today and didn't seem like I was getting anything now, even when the bike is running.

 

Overall length. Some brushes have a "wear line" to indicate need to replacement. One usually goes faster than the other, go ahead and replace them both and clean the commutator rings. Very fine sandpaper will do nicely.
Sometime the replacement brushes come with loaded springs(brush wire goes through center of spring and connects to a metal disc) or just brushes with attached lead wires.
If the replacement brushes just have lead wires, you'll have to unsolder the old ones and solder the new ones in place without loosing the springs( they'll shoot out on you).
If the brushes are loaded, you just cut the lead wire behind the brush and push the remaining wire into the brush holder and put the new brush assembly into the holder.
Some of the holders have a hole at the top edge to insert a pin to hold back the brushes for removal and installation. If you don't have a pin, a paperclip will work.

 

Did you check the field coil resistance at the connector after cleaning? You had 47 ohms before, what is the new reading?

I would check the current through the field coil to determine what is really happening there. Here is a pic on how to check:



Be careful with the connections, an accidental short between the wires could damage the regulator. I used spade connectors covered in heat shrink to keep thing safe.

Yea, that brown wire is the output side of the ignition switch, and if the connection is poor it can cause some voltage loss. However, it looks like you were reading 11.8V on the brown, which is not too far off. It would still be a good idea to clean or replace that poor connection though.

If that's end to end then definitely time to replace the brushes. Probably a good idea no matter what as they aren't too pricey.

 

I actually forgot to test that connection again after cleaning.... Since that plug had melted I soldered the wires together at that point and heat shrank over them. I have new brushes on the way so I will install them, test the resistance between wires and also test current through the rotor. The rings on my rotor have the scoring as well like you mentioned on yours. I used scotch brite but I'm going to pick up some fine grit paper and try to smooth them out more. I'm a little nervous about sanding through them, did you have any issues?

 

No, I used 2000 grit wet/dry with the WD40 and just did a light cleanup thinking it would be too much to try to make them perfectly smooth. I followed that up with the crocus cloth I purchased from Len.

 

I put my new alternator brushes on today and cleaned up the rotor some more. I'm still only getting around 12.5v at idle without my headlight on. It varies while I'm riding (I rigged up a little voltage gauge so I can monitor battery voltage), it seems in third gear around 4k is the sweet spot where I actually get up to 14.5v. Other gears and RPM's peak between 13.8-14.2v. I've got it at home right now so I'm unable to test the rotor voltage until I can get back to the shop.

 

At idle, you are measuring pure, unadulterated battery voltage.

The generating system on these bikes doesn't even BEGIN to kick in until about 1800 rpms (and then only a tiny amount); you have to be at about 2000-2100 rpms before you get full output from the alternator, and that should be around 14.2 - 14.5V, and at any rpm's above that level, there is no (negligible, not worth discussing) increase in voltage output; in other words, once you hit 2200 rpm's, from there until Redline- And-Beyond the alternator will output 14.2 - 14.5 volts, and if it puts out any greater voltage, then the voltage regulator/rectifier is most probably shot.

 

Any reason the voltage would be highest in third gear? Same rpm in different gears gives me lower voltage around 13.8 or so but in third gear in getting up to 14.5. So weird!

 

As for the 3 white wires coming from the stator, what should the voltage be on those? I want to go back and test those as well. I can just unplug them at the regulator connection to test correct? The plug for my regulator melted so each wire is an individual plug now.

 

Well I've been busy with work and my side job so I haven't been able to tear back down and do any voltage tests. I've been riding it a lot though and with the voltage meter on it I can monitor the voltage, I just wanted to through some numbers out there and see if symptoms are indicative of anything. With the bike in neutral and headlight off and throttled up to 2k my voltage will slowly rise to 14.5 but it takes 45 sec to a minute to reach it. Riding in most gears with headlight off I usually hit around 13.8, with headlight on I only hit around 12.8. Now in third gear with headlight off I get up to 14.5, at the same rpm's as when I check it in other gears. With the headlight off in third gear I only hit around 12.8 but in fourth gear I reach 14.5.

 

The headlight on voltages are important. You have good charging voltage with the headlight off, but not always with it on. Engine RMP is important too; what gear you are in dosen't matter. You can be at 4500 RPM in third or at 4500 in first and should get the same voltage readings.

 

That's what I didn't understand how at the same rpm's I get different voltages in different gears?

 

Referesh my memory please. Are we still dealing with the same regulator/rectifier, or has that been replaced?

 

It hasn't been replaced, everything tested good on it so I didn't replace it, I didn't install new alternator brushes though

 

The brushes might be it then. I can imagine that the brushes might be bouncing around a bit as engine vibration changes with different road speeds in different gears. That would be more likely with old brush springs.

 

It's been doing it since installed new brushes, my voltages increased very slightly with the new brushes in place. I purchased the brush kits from Len so it's new springs and all.

 

Have you cheked your meter against a known 12V source, like an adjustable power supply for example?

 

Hey K-Moe, yeah and I've tested with different meters as well, but I also have a voltage meter hooked up to it mounted on the top of my carbs so when I'm riding I can glance down and see what my voltage is at

 

I just did the DC amp test on the field coil wiring, got no reading with key turned on and nothing with it running either

 

I also just retested ohms across the rotor rings and the lowest reading I got was 5.9, is it safe to say I've found my problem and need a new rotor? I've already polished with fine grit paper before and didn't help I reckon.

 

Since you have some charging going on there has to be some current flowing through the field coil. I would re-check the hook-up of the wiring and the meter. Remember the positive meter lead has to be moved and the meter selection moved to dc amps.

That was discussed earlier. The higher resistance with the DMM is not necessarily indicating a fault.

As for the varying charging voltages based on which gear the bike is in that is a strange one. Speculation as K-moe suggested on brush contact and vibrations characteristics in the different gearing is the best theory yet. The only other theory is the different vibration characteristics of different gearing is causing an open / defect somewhere else in the system. That could be a stator winding opening, part of the diode bridge opening, or just a poor connection somewhere that is sensitive to that particular harmonic of vibration.

 

I noticed when I pulled the cover off that one of my brushes is already worn shorter than the other again, they're only a week old. Also my rotor rings aren't completely smooth either, they have scoring and grooves worn in them so didn't know if maybe they just aren't making good contact? Previously when I tested ohms across the rings I was at 4.8 or so but now it's higher. I also ohmed the green and brown wires and got 15.9. I've been riding it for 2 weeks now and it hasn't killed my battery so at least it's charging enough to keep the battery up!

 

The brushes will wear at different rates. That is a function of one being set at a different radius from the other; the outer brush "travels a greater distance" during each revolution than the inner brush does.

 

The only other thing I could think of is maybe pulling the rotor and cleaning the sides that contact the stator? It's pretty dirty in there, I cleaned the inner side of the stator contacts but can't reach the rotor sides.

 

There isn't anything in there to clean. The stator connections are soldered at the stator coils, so the only thing to clean is the contacts at the plug. The slip ring on the rotor is the only cleanable electrical connection on the rotor. I suppose there could be some intermittent connection due to corrosion or thermal breakdown, but that would be rare and would more likely cause infinite (or very high) resistance than it would a varying voltage condition. Still, it never hurts to look. Keep in mind that the rotor is on a taper fit and will be stubborn about being removed. You'll also need to fashion a tool to hold the rotor when you re-torque the holding bolt.

 

This is the only picture I have to describe it, I cleaned the inner "ring" of the stator and got it back to a shiny copper color, after this picture was taken. Does the "side" of the rotor not contact these? I wasn't able to reach in there to clean the grime off it. Please excuse my lack of proper terminology, I'm making it up as I go lol

 

No contact there, only an air gap. The size of the air gap affects efficiency of the system, and nothing you can do to change that. The magnetic field in the rotor generates a voltage as it moves across the stator coils, that is how voltage is generated. The stronger the magnetic field for a set speed of roation, the higher the output.

Well, I was curious about this so thought I would check it out. Note that the charging system is running open loop in this mode with the AC generator output disconnected - no voltage to the IC regulator so no feedback. That means maximum AC voltage will be outputted as the IC regulator supplies maximum current to the field coil trying to increase the output. I did not want to rev too high because of the open loop condition.

Idle of about 1100 RPM = 18.5 VAC
Rev to about 2100 RPM = 30.5 VAC

This is measuring phase to phase, and should be equal between any of the 3 wires.

 

I've got a very small oil leak from where my tach cable attaches to the motor, it's just seeping a little when the motor runs. Is this a common problem with these? It's a new tach cable. I tried an o-ring in there and also wrapped the threads with Teflon tape buts it's still doing it.

 

There is an oil seal (a real proper oil seal) that keeps the oil from going up the cable, and an o-ring that seals the tach drive to the head. Chacal has them both.

One of the best how-to articles ever written. http://xjbikes.com/forums/threads/tach-gear-housing-oil-seal-replacement-w-pics.19538/

 

Perfect! Thank you sir!

 

As soon as I read

I knew it would be a BigFitz thread. Sigh...

 

One risk inherent with rubbing an abrasive across the stationary slip rings, unless you are very careful, is to end up with a slightly unlevel contact surface. I would bet that a little too aggressive rubbing might leave low spots which might be enough to create contact voltage drop each time that spot comes around to the brush. To those who have access to a metal lathe, my best recommendation would be to recondition the scored slip rings with the rotor spinning in a lathe. You could then “face off” the copper until the scoring is gone. Most likely just a skim cut would be necessary, followed up by polishing. I’ve successfully reconditioned many a motor armature this way by turning down their badly scored commutators.
As an aside, I'd like to pass on some info I learned about brushes from literature available on several brush manufacturers websites. Brush manufacturers refer to the scoring that you see as "threading" which they claim results from insufficient spring pressure; thereby contributing to arcing between the carbon and copper. Minute particles of copper become molten during arcing process then get embedded in the brush carbon. From there you now have copper rubbing against copper which leads to galling of the slip ring face. When you replace the brushes and the slip rings are scored there is only partial electrical contact being made. More arcing is likely and more damage to both brush and slip ring.
The bushes in our bikes do not have a provision to adjust the spring pressure behind the brushes. Consequently, as the brush wears down the spring pressure decreases. I’d say that the best practice is to check your brush length occasionally and replace them as they reach their service limit as prescribed by Yamaha.

 

Is it me or is anybody else able to open his photos?

 

They were hosted elsewhere. If he pulled them then they are gone. You might try a google search. Fairly often you'll find at least the thumbnails.

 

..whats up with all missing photos?