alternator brush length

[brucealmighty]

The manual states that the minimum length for the alternator brushes is 10mm and that they should be changed every 6,000 miles. The bike has 17,000 miles, 3,000 of which are mine since I bought it. I have no idea if the brushes have ever been changed. If you can view the photo, you'll see that there is a line etched across the brush. Is the minimum length referred to by the manual the entire length of the brush, or the distance from that line to the end, which I think is probably the amount of brush that protrudes from the holder?

[TomB]

Are they out of an XJ?

I didn't know my XJ had brushes (I've only just got it ), is that the wider than XS alternator lump then?

Any other brushes I've had I've kept using as long as they had plenty of travel and spring strength left.

Tom

[brucealmighty]

Originally posted by TomB
Are they out of an XJ?

I didn't know my XJ had brushes (I've only just got it ), is that the wider than XS alternator lump then?

Any other brushes I've had I've kept using as long as they had plenty of travel and spring strength left.

Tom

Yes, sorry, I should have said, it's a 1982 XJ1100. I don't know what you mean by "alternator lump". I've just installed a new battery and I wanted to make sure the charging system is up to speed. I don't think it is. I have a charger that has a "check alternator" function. It reads that the alternator is bad until I rev the engine above 2K, then it goes green. Maybe that is normal, I don't know. I tried to connect a set of fog lamps, which I didn't think would be a problem for a bike this size. When I turned them on, I could actually hear the engine labor down. Didn't seem like they should have been putting that much strain on the charging system. The voltmeter I have is just the kind with a needle, not a digital readout, so I can't get a really accurate reading on the alternator output. I just know that after shelling out $85.00 for a new YUASA battery, I'll be steamed if I get stuck somewhere (again). I curse the people responsible for eliminating kick starters!

[boyat68]

I have never changed the brushes in a motorcycle generator, however I have in several other motors and generators. That line you see is the inscribe line that the manufacturer places on the brush to allow a sight line that a cautious person would change before the brushes wore below that line. The reason is that the attached braided connection is embeded up in the carbon block and if you happen to allow the block to wear below that line then your communtator might be scored by the embeded connection and ruin your whole shaft. I would say replace them before the line was worn. In the SX1100 manual it indicates a minimum brush length as 5.5mm or 0.22 in.

[TomB]

I don't know what you mean by "alternator lump"

The XJ has an extra, wider than the XS, centre to its alternator cover, I guess this is where the brushes are.

Here is an XS11 alternator cover.

[brucealmighty]

Originally posted by TomB

The XJ has an extra, wider than the XS, centre to its alternator cover, I guess this is where the brushes are.

Here is an XS11 alternator cover.

Yes, the XJ has a "lump" and that's where the brushes are.

[brucealmighty]

Originally posted by boyat68
I have never changed the brushes in a motorcycle generator, however I have in several other motors and generators. That line you see is the inscribe line that the manufacturer places on the brush to allow a sight line that a cautious person would change before the brushes wore below that line. The reason is that the attached braided connection is embeded up in the carbon block and if you happen to allow the block to wear below that line then your communtator might be scored by the embeded connection and ruin your whole shaft. I would say replace them before the line was worn. In the SX1100 manual it indicates a minimum brush length as 5.5mm or 0.22 in.

Then it would appear that there is plenty of life left in the brushes I have. I've already purchased a new set. Guess I'll just hold on to them until needed.

[trbig]

Hmmm... My XJ book which is an actual Yamaha service manual says initially replace at 8k miles, then every 10k miles?? Mine have @ 15k on them and look about like yours still.

I don't know where you bought the new ones at, but Partsnmore has them for $5 each, you'll just have to re-use that metal bracket.


Tod

[brucealmighty]

Originally posted by trbig
Hmmm... My XJ book which is an actual Yamaha service manual says initially replace at 8k miles, then every 10k miles?? Mine have @ 15k on them and look about like yours still.

I don't know where you bought the new ones at, but Partsnmore has them for $5 each, you'll just have to re-use that metal bracket.


Tod

I also have the official Yamaha XJ1100J manual and it clearly states: oops. That's every 6,000 km (10,000 miles).

[planedick]

Fog lights?

The charging system isn't up to the extra lights. The charging system is barely enough to carry the stock lights. Basically you have about 4 AMPS left or about 48 Watts for any additions unless you change lots of other lights to LED's.

[TopCatGr58]

Hey Bruce and Tod,

I just looked at the XJ manual, and what it says about the changing intervals doesn't make sense....6000 km's OR 10K miles? I wonder if that's supposed to be the other way around, because 6k km's is about 4k miles, whereas 10k km's would be closer to 6k miles?

Secondly, Bruce, on the left side of that page of your manual, it tells you that you will get about 14.5 volts at 2K rpm, so yes, the charging system doesn't crank much at idle! The manual in the specs section also states that it will put out a max of 26 amps at 5k rpm!

It's been said it takes about 10 amps for the TCI, then you get to start adding up power drain for ignition coils, computer, lights, and like Dick said, you run out of juice fairly quickly. Running at cruising speed/rpm you should be able to power the extra driving lights, but will need an easy access switch to turn them off in town/stop and go traffic! The tail lights/brake lights and turn signals can give you some added amps by converting them to LED's since they typically draw about 0.3 amps LEDs vs. 2.3 amps for 27 watt brake/turn signal lights per bulb, and .75amps for the 8 watt driving lights.

Your extra lights, IF halogen, are probably 55 watts each, divide by 12 volts, you get total amps draw, about 9 amps!!
T.C.

[brucealmighty]

Re: Fog lights?

Originally posted by planedick
The charging system isn't up to the extra lights. The charging system is barely enough to carry the stock lights. Basically you have about 4 AMPS left or about 48 Watts for any additions unless you change lots of other lights to LED's.

Yeah, that's the conclusion I've come to. The fog lights would have been cool, and an added bit of safety, but I'll put them on my truck instead.

[trbig]

I just looked at the XJ manual, and what it says about the changing intervals doesn't make sense....6000 km's OR 10K miles? I wonder if that's supposed to be the other way around, because 6k km's is about 4k miles, whereas 10k km's would be closer to 6k miles?

He just left off a one (1). It is 16k kilometers, or 10k miles.






Tod

[fredintoon]

"I also have the official Yamaha XJ1100J manual and it clearly states: oops. That's every 6,000 km (10,000 miles)."

Hi Bruce,
my calculator says that 6,000km = 3,720 miles. Get a lot of speeding tickets, do you?
If your engine is "sucked down" when you turn those extra lights on, it does show that the alternator is working, right?
Do a search for "LED light conversion" to see how several list members have reduced their bike's power consumption.
I doubt that a kickstarter would help you. The '79 & earlier XS11s had them in case the electric starter crapped out, not to compensate for a low battery. If the battery is too flat to spin the starter there may not be a sufficiently high voltage left in it to work the transistorized thingies in the ignition.

[brucealmighty]

<br><p>Okay, is someone trying to confuse us. Actual photos from actual Yamaha factory service manual. Look at item 2.C.