First coil of the season. Almost forgot how to do it.... 
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For Sale - Rewound Alternator Rotor
- Thread starter Jim
- Start date
Weapons of mass destruction... production.... induction... 
tommytwohands
XS650 Enthusiast
Yamaha Graveyard
XS650 Enthusiast
What a great guy to work with and fantastic workmanship my rotor came back looking like art work, I didn't want to hide it behind the stator. I sent Jim a rotor that I could barely ohm it had 1.7 on my fluke and jumped and auto ranged all over the place along with only charging 12.1 volts at 3K. Now the fluke jumps to 5 ohms and holds steady and the thing charges up to 14 volts I put Jim's rewind on tightened the last bolt "shifter" with the bike on a lift I stood up and turned the key and the thing snatched the 10mm wrench out of my hand from probably 6 inches away. If you need this done don't hesitate to use his service, You will not be disappointed. Thank you Jim!
The picture is my phone adapter after the first start battery volts were soft at 11.9 because I ran it down diagnosing. It's now at 13 at an idle.
The picture is my phone adapter after the first start battery volts were soft at 11.9 because I ran it down diagnosing. It's now at 13 at an idle.
Attachments
Never say die....
Honda 4 rotor... went to take it apart and the ring plate was stuck fast. Kept adding force 'till it finally let go....
Yeah, not exactly the "give" I was hoping for. I figured out what happened... somewhere in it's past the outer ring was damaged and recut. I'm guessin' they chucked it up in a lathe with a shaft and centering cones. That flared the center threaded flange just enough (.013") to effectively "rivet" the plate in place. I was doomed from the start.
Anyway, while debating how to break the news to the customer, it dawned on me that the plate looked close to the same size as an XS650 ring plate. Dug around my spares and found one. I had to cut the flare off the end of the rotor and the XS plate fell right into position. It's also about a 1/16" larger in diameter and.... it has 6 mount holes vs. the Honda's 4. The copper rings however, were identical.... sumbich... maybe this'll work after all.
Finished taking the rotor apart and marked and drilled 6 holes to match the XS plate. Threaded them with a 3X.5mm tap.... which was quiet nerve wracking btw....
Cut a 1/16" off the OD of it and wound a 21awg coil for it and put it all back together....
Good as new. Where there's a will there's a way.
Honda 4 rotor... went to take it apart and the ring plate was stuck fast. Kept adding force 'till it finally let go....
Yeah, not exactly the "give" I was hoping for. I figured out what happened... somewhere in it's past the outer ring was damaged and recut. I'm guessin' they chucked it up in a lathe with a shaft and centering cones. That flared the center threaded flange just enough (.013") to effectively "rivet" the plate in place. I was doomed from the start.
Anyway, while debating how to break the news to the customer, it dawned on me that the plate looked close to the same size as an XS650 ring plate. Dug around my spares and found one. I had to cut the flare off the end of the rotor and the XS plate fell right into position. It's also about a 1/16" larger in diameter and.... it has 6 mount holes vs. the Honda's 4. The copper rings however, were identical.... sumbich... maybe this'll work after all.
Finished taking the rotor apart and marked and drilled 6 holes to match the XS plate. Threaded them with a 3X.5mm tap.... which was quiet nerve wracking btw....
Cut a 1/16" off the OD of it and wound a 21awg coil for it and put it all back together....
Good as new. Where there's a will there's a way.
A Honda with the heart of a XS650 love it.Never say die....
Honda 4 rotor... went to take it apart and the ring plate was stuck fast. Kept adding force 'till it finally let go....
View attachment 216499
Yeah, not exactly the "give" I was hoping for. I figured out what happened... somewhere in it's past the outer ring was damaged and recut. I'm guessin' they chucked it up in a lathe with a shaft and centering cones. That flared the center threaded flange just enough (.013") to effectively "rivet" the plate in place. I was doomed from the start.
View attachment 216500
View attachment 216501
Anyway, while debating how to break the news to the customer, it dawned on me that the plate looked close to the same size as an XS650 ring plate. Dug around my spares and found one. I had to cut the flare off the end of the rotor and the XS plate fell right into position. It's also about a 1/16" larger in diameter and.... it has 6 mount holes vs. the Honda's 4. The copper rings however, were identical.... sumbich... maybe this'll work after all.
Finished taking the rotor apart and marked and drilled 6 holes to match the XS plate. Threaded them with a 3X.5mm tap.... which was quiet nerve wracking btw....
View attachment 216502
View attachment 216503
Cut a 1/16" off the OD of it and wound a 21awg coil for it and put it all back together....
View attachment 216504
Good as new. Where there's a will there's a way.
Dang Jim! That’s pretty darn impressive!
When I saw that broken slipring assembly for the Honda Four it reminded me of the I believe it was my RD200 or was it the RD400. Any how I was having a charging problem and when I removed the brush holder saw a slipring assembly that looked like that Honda one.
A bit of checking and I found that one or two of the screws that held it in place had stripped threads. What to do now? After digging out all the epoxy that covered the screw heads I found a tap for a machine screw that was just a little larger than the original metric screws. I taped out the holes for the machine screw thread, probably something like 10-24.
I then cleaned everything up real good including the crack in the insulator. Filled the crack with epoxy and coated all the contact points including the screws with epoxy. Let it set up overnight and then mounted in the lathe at work and took a couple light cuts to true the sliprings up. Put motor back together that night and fired it up and to my surprise it was charging just fine. Sold the bike latter and it was still working when it left.
Sometimes even a dummy like me can get lucky!
A bit of checking and I found that one or two of the screws that held it in place had stripped threads. What to do now? After digging out all the epoxy that covered the screw heads I found a tap for a machine screw that was just a little larger than the original metric screws. I taped out the holes for the machine screw thread, probably something like 10-24.
I then cleaned everything up real good including the crack in the insulator. Filled the crack with epoxy and coated all the contact points including the screws with epoxy. Let it set up overnight and then mounted in the lathe at work and took a couple light cuts to true the sliprings up. Put motor back together that night and fired it up and to my surprise it was charging just fine. Sold the bike latter and it was still working when it left.
Sometimes even a dummy like me can get lucky!
Jim AKA Dr. Frankenstein!
Cool!
Cool!
Jim, as a wise friend of mine once said "...nothing was ever made that couldn't be modified."
This all came from this thread. I'm including it here to hopefully help anyone with similar problems.
'81 TCI bike...
"If I ground out the green wire for one of the brushes the “slap test” is very good but the bike will not rev up (sounds like it hits a rev limiter anything past an idle). When I disconnect the ground for the green wire the “slap test” is bad (no ground to one of the brushes) but the bike revs up just fine. Ive also tried both of the regulators I have."
This is commonly known as the "weak magnet syndrome." The theory is that the TCI trigger magnet is so weak the rotors charging magnetism is drowning it out, causing the ignition to misfire.
More details....
"Wiring harness is chopped down to bare minimum due to this being a bobber build. Rotor is from mikesxs (slip rings continuity reads 5.3ohms off bike). Stator is also from mikesxs (phase wires read 1.0 ohms between all 3 white wires). One regulator is a mikesxs and one seems to be stock (no change between either one)."
I referred him to this thread where a similar issue was discussed.... and it's resolution here.
I rewound a TCI rotor and sent it his way. Yesterday I received a reply from him...
"Jim I received the part and recently had the time to install it. Problem fixed!! Ive taken the bike on 4 good rides and no issues. I can't thank you enough for the help."
Someone 6 or 8 yrs ago tried to clean up damaged slip rings on a Chinese rotor. Don't recall who it was.... @MacMcMacmac perhaps?
Anyway, when they chucked it up in a lathe, they cut through the copper rings almost immediately. "Paper thin" I believe was the description used.
The copper rings on the factory rotor are about 1.5mm thick... a fair bit more than "paper thin."
The gist of all this is that I believe the copper rings block most of (enough of) the charging system magnetism. Enough so that the TCI sensor (pickup) can cleanly read the trigger magnet, allowing both normal ignition operation and charging. The Chinese (Mikes) rotors appear to be hit and miss. Perhaps poor quality control on the copper thickness? Dunno...
But, this is the 4th case I'm aware of where a stock rewound rotor fixed a problem such as this, and as far as I know, no cases where it didn't fix this issue (with the Chinese rotor).
So don't throw away those factory TCI rotors. Ya never know when you might need 'em.
Here's a video showing the blocking affect of the copper ring. It was while I was testing for something else that I noticed it.
'81 TCI bike...
"If I ground out the green wire for one of the brushes the “slap test” is very good but the bike will not rev up (sounds like it hits a rev limiter anything past an idle). When I disconnect the ground for the green wire the “slap test” is bad (no ground to one of the brushes) but the bike revs up just fine. Ive also tried both of the regulators I have."
This is commonly known as the "weak magnet syndrome." The theory is that the TCI trigger magnet is so weak the rotors charging magnetism is drowning it out, causing the ignition to misfire.
More details....
"Wiring harness is chopped down to bare minimum due to this being a bobber build. Rotor is from mikesxs (slip rings continuity reads 5.3ohms off bike). Stator is also from mikesxs (phase wires read 1.0 ohms between all 3 white wires). One regulator is a mikesxs and one seems to be stock (no change between either one)."
I referred him to this thread where a similar issue was discussed.... and it's resolution here.
I rewound a TCI rotor and sent it his way. Yesterday I received a reply from him...
"Jim I received the part and recently had the time to install it. Problem fixed!! Ive taken the bike on 4 good rides and no issues. I can't thank you enough for the help."
Someone 6 or 8 yrs ago tried to clean up damaged slip rings on a Chinese rotor. Don't recall who it was.... @MacMcMacmac perhaps?
Anyway, when they chucked it up in a lathe, they cut through the copper rings almost immediately. "Paper thin" I believe was the description used.
The copper rings on the factory rotor are about 1.5mm thick... a fair bit more than "paper thin."
The gist of all this is that I believe the copper rings block most of (enough of) the charging system magnetism. Enough so that the TCI sensor (pickup) can cleanly read the trigger magnet, allowing both normal ignition operation and charging. The Chinese (Mikes) rotors appear to be hit and miss. Perhaps poor quality control on the copper thickness? Dunno...
But, this is the 4th case I'm aware of where a stock rewound rotor fixed a problem such as this, and as far as I know, no cases where it didn't fix this issue (with the Chinese rotor).
So don't throw away those factory TCI rotors. Ya never know when you might need 'em.
Here's a video showing the blocking affect of the copper ring. It was while I was testing for something else that I noticed it.
You're outta warranty now bud...
Back when I was working on airplanes I used to tell my pilots "90 days or 90 feet".... whichever comes first. 
Yes.
Very interesting discovery Jim. Yes, I tried to clean up a rotor plate and got nothing but a mess of oily smelling burlap and copper foil that was once pressed into the shape of a rotor plate. In my travails that year I managed to mess up the plate on a Rick's alternator that had a bad keyway and didn't go onto the shaft far enough. It dragged on the alternator frame, destroying the copper rings and magnet. I did manage to clean up the rings an put in a neo magnet, but the bike became hard to start and kickbacked heartily. This went away when I put the oem plate on the Rick's rotor. I found out later the neo magnet was installed with the opposite pole out compared to the oem rotor. I wonder if it was matching the background magnetic field of the rotor and getting drowned out? Can you alter the polarity of the field by running the current in the opposite direction?
