Another Rotor Thread...

Wondering what the best source is for a replacement rotor?


My 1980 was charging pretty weak, and I also noticed a pretty heavy load on the battery with just the key in the on position. Checked the load at around 11amps!

Anyhow, removed the brushes, and checked the Ohm resistance between my slip rings and got 1.4 on the meter (and about .3 just touching the leads) so I'm at about 1.1 Ohms. A old cycle place in town had a used one, but didn't have a meter to check, so they let me bring it home. It checked out exactly the same as my current one. Now not trusting my meter, I grabbed a 10 Ohm resistor and checked it out on my meter and it was about dead on.

OK, I'm 99.9% sure my rotor, and the loaner is bad. What to do next? I've read a pile of threads on this forum, and some are from years back, and the suppliers are either out of business, or the ones recommended back then seem to have lost their sterling reputations.

So, back to my question, if you needed a new rotor, where would you go now?

Custom Rewind
http://businessfinder.al.com/850071/Custom-Rewind-Birmingham-AL

Yes, your rotors are shorted. You should be reading close to 5 ohms.

Used = gggGary
Reman = Custom Rewind

How about 650 Central? Are their rewound rotors and stators any good?

I found a new one on Ebay for about $80. That was a few years back. Still charging on! (sorry, couldn't help myself. LOL!)

Thanks for the suggestions so far. Anyone have any experience with RM Stator Inc out of Vermont?

$64.50 with free shipping - http://www.ebay.com/itm/Charging-Al...sh=item4406676dac:g:8u0AAOSw6ShZUrOX&vxp=mtrp
It seems to me I picked up a stator for my snowmobile from them years back that has been working great.

ihaxs650 said:

How about 650 Central? Are their rewound rotors and stators any good?

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I haven't seen comments on his either way. His site indicates he has them rewound. I like dealing with him, but I can not comment on the rotor.

bwthor said:

Thanks for the suggestions so far. Anyone have any experience with RM Stator Inc out of Vermont?

$64.50 with free shipping - http://www.ebay.com/itm/Charging-Al...sh=item4406676dac:g:8u0AAOSw6ShZUrOX&vxp=mtrp
It seems to me I picked up a stator for my snowmobile from them years back that has been working great.

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Nice to see someone use their VOM to measure amps.........................quite rare on this site.
Yes you need another rotor.
RM Stator buys their electrical parts from Electrosport in California. Electrosport is is owned by Procom Engineering, which as 2 manufacturing plants in China.
Those Chinese parts are low quality and may fail early. I would not buy from them. I believe these are the same parts sold by
Mikesxs, HHB, and TCbros.

Custom Rewind has a reputation for very high quality rewinds. It would be the best choice.

I bought a rewound rotor from a 650 Society member 15 years ago. He's not sure it came from Custom Rewind. Wherever it came from, it's still charging my battery and triggering my sparks.

That one in your link doesn't have a picture of the important part, the front face. Without that, you can't tell if the rotor has the magnet needed for the '80 and later TCI ignition or a timing mark. Yes, a timing mark. I guess some of these China ones don't have one. That pretty much makes it useless in my eyes.

Re. 650 Central's rotors: they're rebuilds from Custom Rewind. A rewound rotor from CR is better than OE. CR uses larger gauge wire than Yamaha wanted to pay for. The result is that their rotors magnetize fully at 4 ohms resistance rather than OE 5+ ohms, and thus run cooler. Insulation is also superior to OE.

5twins said:

That one in your link doesn't have a picture of the important part, the front face. Without that, you can't tell if the rotor has the magnet needed for the '80 and later TCI ignition or a timing mark. Yes, a timing mark. I guess some of these China ones don't have one. That pretty much makes it useless in my eyes.

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In the description, they do state that they have the timing magnet. Either way, sounds like they should be avoided even at the low cost.

grizld1 said:

Re. 650 Central's rotors: they're rebuilds from Custom Rewind. A rewound rotor from CR is better than OE. CR uses larger gauge wire than Yamaha wanted to pay for. The result is that their rotors magnetize fully at 4 ohms resistance rather than OE 5+ ohms, and thus run cooler. Insulation is also superior to OE.

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Thanks Grizld1 and the rest. I'll be checking Custom Rewind out and hoping the price isn't too bad.

grizld1 said:

Re. 650 Central's rotors: they're rebuilds from Custom Rewind. A rewound rotor from CR is better than OE. CR uses larger gauge wire than Yamaha wanted to pay for. The result is that their rotors magnetize fully at 4 ohms resistance rather than OE 5+ ohms, and thus run cooler. Insulation is also superior to OE.

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Important info here Griz...........I was looking on ebay at a rewound rotor and they stated it ohm'd out good at 4.1ohms..........

All the info posted and read all say 5ohms was the optimin............The rewind had been done buy custom rewind, although they were not the seller...........

as far as i was concerned/knew the seller was selling a defective part.............Your info clears this up.......

In my journey to learn everything the hard way I recently sent Custom Rewind a rotor to be rewound. (I'm going back to stock after running/not running a PMA kit.) I have a '82 with a PAMCO, so the magnet/pickup isn't necessary, however, I wasn't 100% sure about that (still learning) and Kirk at Custom Rewind offered to swap my rotor for a rewound TCI system rotor so I'd be covered. But the rotor they sent me didn't fit my bike. I couldn't get it to seat fully on the crankshaft. It was as if the taper was too severe/the inner diameter was too narrow towards the outside.

I happened to have 3x rotors on me at the time, 2x TCI (1x rewound, 1x OEM) and 1x points, tested them all for fitment and the only one that did not fit my bike was the rewind. NOTE: none of the rotors came from my bike, I foolishly sold that rotor when I converted the charging system from stock to PMA.

My understanding was that rotors are interchangeable. Is that not the case? I'd like to be able to give Custom Rewind some insight to what may have happened.

Also, Custom Rewind is going to replace the rotor that doesn't fit. I'm sending them their rotor back as well as one of the ones that fit so they can check the taper, inner diameter, etc... Just to be clear, this isn't a negative comment about Custom Rewind (they have been very helpful). This is just a question about why the rotor didn't fit.

Thanks!

Yeah, thanks Griz. I had one done by Tim Parrot that came back reading four ohms. It worked fine but I always wondered about that difference.

The one I've been running for 15 years is >4 ohms. Works great!

TCI and earlier points rotors are the same except for the magnet on the TCI unit. They both fit the same. You can run a TCI rotor on an earlier points bike or with a Pamco. The magnet simply won't get used.

And when I referred to the timing mark, I wasn't talking about the magnet. I meant the actual slash mark you align with the timing marks on the cover. You need it for checking the ignition timing and also for finding TDC to set the valves. Selling a replacement without that mark is just plain stupid.

That's what I thought! Thanks for clearing that up.

5twins said:

That one in your link doesn't have a picture of the important part, the front face. Without that, you can't tell if the rotor has the magnet needed for the '80 and later TCI ignition or a timing mark. Yes, a timing mark. I guess some of these China ones don't have one. That pretty much makes it useless in my eyes.

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Amen, 5T - even if an aftermarket rotor shows a timing mark, it may not line up with the TDC mark on the timing tab with pistons at TDC, especially if its keyway and/or the OEM key had to be "dressed" to get the rotor seated on the crank. That was my experience after installing an aftermarket rotor. Did the piston stop - degree wheel thing twice to make sure; with pistons at TDC per the degree wheel, the rotor mark was about 4 degee CCW from the timing tab TDC line. Widening the keyway or narrowing the key are obvious ways in which relatively minor metal removal so near crank center might translate into several degrees off true TDC at its circumference where the TDC mark is struck. My '82 has an adjustable timing tab; I was just able to align it with the rotor mark with pistons at TDC when moved as far as it would go. Then used the degree wheel to set a new 40 degree BTDC mark, since the left edge of the notch in the LH cover no longer could serve that purpose. My point here is that the angular relationships among the rotor keyway, TCI trigger magnet placement and rotor TDC mark are critical quality control items for TCI-equipped bikes - if I hadn't stumbled on this issue with my new rotor, I'd be running 36 degrees full advance without knowing it. Maybe no big deal, or maybe even better, to run a bit less than 40 (mine is set now at 38 - "slotting" the hole in the upper pickup mounting tab gives some adjustability), but suppose the error was the other way, and I was running 44 full advance without knowing - not good for the pistons in our beloved 650's. One way to avoid this risk is to get an OEM rotor rewound, trusting original Yamaha quality control. Even then, it might be good practice to check alignment of TDC marks on any "new" rotor and timing tab with pistons at true TDC.

Aldo5468, thank you for posting this. I hadn't considered that the timing mark on my stock, but not stock to my bike, rotor and stator may not have "correct" timing marks for TDC.