Charging Challenge - WOW

[Anonymous]

the stator and RR both pass the same checks as the originals did, so are good according to the flowcharts in the garage area. I am definately in the market for a rotor(and puller) as it is really getting nice these days and I'm missing out!

[IanFrancisco]

Here's some part numbers I found for an '85 GS700ESF.

From PartsFish at powersportspro.com,
ROTOR 31402-08A00 $167 and discontinued

from BikeBandit.com,
ROTOR 491123-001 $212 and still available.

For that kind of money I would look into getting my rotor re-magnetized. How hard could it be?

The part number for the rotor I have is supposedly 31402-45030 ('80 GS450ST). Haven't checked the actual part yet though...

[Anonymous]

Yeah those are the same numbers I saw.. in the bike bandit pics the rotor you have is different(no threads for the puller on the upper part of the center hub, just flats so I guess it screws off or something). The rotor new is big money... I'm going to keep watching for used ones and hope I can find one I guess.

Thanks

-Jim

[IanFrancisco]

I hope you're right about the rotor. I don't think I've ever heard of a rotor going bad by losing its magnetism. I have heard of the magnets falling off a Kawi EX500 rotor. Some of the old 60's bikes had an "exciter" coil on the rotor, connected thru brushes and an armature to the battery, basically a rotor that was an electromagnet. If the battery was weak or went dead, no power for starting even with a kick-start. If you're getting close to 50 or 60 Volts AC out of the stator at 4500 or 5000rpm there's no way the rotor's that bad. Guys with the EX500's with broken magnets just break off the magnet on the opposite side and ride like that. It would be handy if you could beg borrow or steal another rotor to try, just for troubleshooting purposes. Obviously if you had the same trouble with a different rotor you'd know to look elsewhere. I think I would get a 1 or 2 Amp battery charger and just ride anyway. $29.95 at Sears. Disconnect the lights if they can't be turned off. You could probably ride for 8 hrs. before the battery got too weak. Even with the lights on I was able to ride an hour and a half before the battery got too weak to run the starter, and I was still able to push start it (easy when the bike only weighs 400lbs.). Only once did the battery get so low that I forgot and flipped on the signals just as the light turned green, which caused an embarassing stall requiring me to push to bike out of the road with cars waiting to go, then do a bump start at the side of the road. That got my heart rate up a bit!

[Anonymous]

Hey Ian... that's a great work around until I can solve the problem.. I pulled the old airbox in favor of cone filters, so I have a huge area under the seat... so I could put a car size battery in there almost. I want to participate in the Ride for Molly Bish coming up June 26th, and this might be the cheapest way to do it. I think I'll also see what kind of current the bike draws while running and then get a decent idea of the ride time before I die ha... ah well. I wish I had the later style all-in-one case alternator like the katanas.

[IanFrancisco]

I just replaced the stator in my bike yesterday. It wasn't that hard. Gotta have the impact driver for the Phillips heads, and patience. Took about three hours. Got the old gasket off intact and reused it with some of that yellow rubber-cement-like gasket sealer. Reused the grommet. Replaced the Phillips with Allen heads. Soldered the connectors on. Changed the oil, oil filter and o-ring at the same time. So far no leaks! Pulling the rotor off would be next to impossible without the special puller or equiv. and on my bike there are some small starter clutch parts behind it that would require some careful disassembly and reassembly. The new Electrex stator and reg/rec put out 15 VDC at 2500rpm and the same at 4500rpm with the lights off. Rode 80 miles of combined town/canyon/freeway with the lights on and had a live battery after three hrs. of riding. Hallelujah! I might be able to just jump on and ride today without getting my hands dirty... oops, better check the tire pressures. Been two weeks...

[Anonymous]

I think I may bite the bullet and buy a rotor... but in any case, where can I buy the rotor puller for it?

[IanFrancisco]

Bike Bandit has one for under $10 that might fit your bike:

http://www.bikebandit.com/partsbandit/product~pf_id~3279872~dept_id~1215878.asp

GS550/650/750 Early 1100, Most 4 cycle street models.

I would make darn sure that the rotor was really bad before I spent the money on a new one. I know you did a thorough job of troubleshooting your charging system but for that price it might be worth it to go over it again. I would use a good digital multimeter for testing and per the Stator papers make sure the battery is fully charged before testing. I bought a used rotor and stator on fleabay and I can tell you that there's nothing much to these rotors. On the one for my bike there's just three big magnets on the inside. There's also some small starter clutch parts that would require some careful disassembly and reassembly. If you get the puller you could remove your rotor and test it before spending the money on a new one. The one I bought would attract and hold up a large screwdriver, but not as strongly as you might think, maybe about 2-3 lbs of force required to pull it away from the magnets.

In case you're interested, here's a link to an old article about re-magnetizing Lucas magnetos used in old Brit bikes.

http://www.britishonly.com/pdf/lucas/sectionD6.pdf

Oh and in reading back thru this thread I should mention that the new Electrex regulator I installed did not pass the Stator Papers tests exactly. Showed the .5V with red test lead connected to RR black ground wire but did not show any volts with red test lead connected to red RR wire. The rectifier portion is a diode bridge and diodes are designed to pass current one way and not the other. In my factory service manual the only tests for the rectifier can be done with a simple test light and battery, or the diode test mode of a multimeter. The factory manual was/is only concerned with continuity. I can't remember the test exactly but it is something like this: red test lead to red output wire, black to each of the three wires that would connect to the stator (separately). Should be no current flow (OL or no beep from the meter, or no light from a simple continuity tester). Reverse polarity (black test lead to red output wire) should show current flow. I could have this test backwards. The second series of tests is doing the same thing only with the test leads connected to the ground wire of the RR and the results should be exactly the opposite. Finally there should be infinite resistance or OL between the red and black wires of the rr. I don't have a pic hosting source or I would scan the pages from my factory manual and put 'em up for public use. If you'd like I can email 'em.

The only reason I mention all of this is that some people have mentioned that their Electrex RR's have either been bad from the factory or have not lasted long. I suppose if someone stuck in a new RR and their stator or harness was bad it could toast the new (expensive!) RR. On these GS's it is more commonly the RR that fails which subsequently toasts the stator. That was the sequence with my bike. The new RR did not solve my charging system problem by itself. Turned out the stator was weak (brittle crumbly insulation) from being cooked by a bad RR. There was nowhere for the power to go but to overheat the stator. The weak stator did not seem to bother the new RR, but charging voltage was still low. What confused me was that charging voltage would be 14 VDC or so when the motor was cold but as soon as it got up to operating temp. the charging voltage would drop to 12.2 VDC or something unusable. With the new stator and RR and a squeaky clean harness with an extra ground wire directly from the RR to the battery neg. I have 14.9 VDC at 2500 rpm and 14.9 VDC at 4500rpm. No more riding without lights!

Now if I could just figure out why the bike started running crappy. No power from 5.5K to 7k at half or full throttle. I used to be able to rev from 3k to 8k in any gear at about half throttle with plenty of power. It happened after I replaced the air filter. Even though the airbox looked very clean I must have got some dirt in there. Or maybe the new charging system is toasting the ignitor??

[Anonymous]

yeah I find it so unlikely that it is the rotor.. I was actually going to pull it and bench test the whole charging system instead of testing it on the bike crank itself (that way I can play with speed, and offset etc).

That puller looks like it won't work.. the rotor has external thread on it, and the crank bolt goes down through the middle.. so I'd expect to see something that goes over the external threads and then pushes off via the internal threads?

If you started having those power probs right after replacing your air filter, it sound like you're now getting a lean condition. The older dirty air filter could have impeded flow enough that you ended up where you should be air/fuel wise... after replacing the filter, you now have a lean condition since you're flowing more air... when is the last time you cleaned out the carbs/jets? Have you tried choping the plugs during this loss of power to look at the plugs to verify the lean condition? (just stay in say 2nd or 3rd, rev into the weak range, and kill the ignition and pull the clutch and roll to a stop, then pull the spark plugs on the side of the road and check them out)

-Jim

[IanFrancisco]

I didn't post the whole story on this thread but did elsewhere. The old filter was non-oiled white gauzy stuff topped by block of non-oiled foam in the stock airbox that was flowing quite well but probably not filtering much (installed by the PO). So, I decided to go with the stock oiled-foam filter. When I did that it was a little large but I crammed it in there anyway and didn't soak up the extra oil. It was oiled well enough out of the package to get on my hands but not drip. It was purchased from BikeBandit OEM parts so I figured the manuf. knew how much oil should be on these filters. I've never had a bike with an oiled-foam filter that I knew of or did anything about in my younger years and this is only my second bike now that I'm back into it. Anyway, the bike sounded strangled and misfired at 6k with a new filter. Flowing less air than before. It sounded muffled, didn't have the nice "whoop" sound from the intake like before. I reinstalled the old dry filter and replaced the plugs even though the old ones didn't look bad, weren't oil-fouled and were the right tan color. Cleaned the harness connectors (again) going to the coils and ignitor. The spark wasn't as fat as I'd like to see but it was there and it was blue. I also checked the centrifugal advance mechanism to make sure it was moving freely but have not checked the timing. It was running great before and the timing wasn't tampered with so it should still be on. I have some used coils coming from eBay that I will try but I figure it's time to do the carb teardown and clean. I've never had to mess with jetting or plug chop testing before, always ran the stock airbox and exhaust and got the expected stock performance. I have torn carbs down and cleaned them, though. The whole bike was kept clean by the PO and the old filter and inside of the airbox was very clean. The bike has been a garage queen since at least 1995, the last time it was reg'd. It's kind of frustrating 'cause all I had to do was NOT mess with it and it would be running great right now and probably would have all summer. But I was concerned about the funky non-standard air filter not doing its job... argh