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Discussion Starter · #1 ·
Hi all, new to the forum hope someone can help. I have a problem with my 89 sportster, it stopped charging, i was told to get a new regulator/rectifier i did this to no avail, checked my alternator output to find i had non, took it apart and found the old problem of the magnets falling off and wrecking the stator.No problem found a new alternator stator on ebay, a mate had a good second hand rotor, fitted them and tested the output, at 2000 rpm i have 10v AC and at 3000 i have 15v ac, clearly not right, so i got another stator brand new and the results are still the same, both stators test ok with the meter, not grounding, resistance as it should be. What can be wrong here pulling my hair out !!:hmmm:
 

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The magnets are part of the clutch basket on the sportster correct? You said you replace them, so does that mean you replaced the clutch basket? Or did you do somehow just replace the magnets?
 

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I don't completely understand either! The magnets on an 89 are part of the clutch shell and if they are damaged you must replace the clutch shell. There is no way to replace them without doing so. Is that what you mean by a second hand rotor? If I recall correctly your numbers are definetly not correct, I believe the stator puts out between 12 and 18 VAC per 1000 RPM's. I'm wondering that if you replaced the clutch shell with your friends that maybe it really wasn't a good one...
 

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Discussion Starter · #4 ·
Sorry, a local workshop had a complete clutch basket so i fitted that, it is second hand but in perfect condition. This has me thinking, this must be the most simple charging system around but i just can't get it to produce the voltage, i am getting about one third of the voltage i should be, new stator good rotor the magnets are strong. HELP, I am missing something but what ?
 

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with the stator in the bike, measure between each pin to ground and make sure you have no shorts to ground, at the moment that is all I can think of to explain the low AC voltage you measured.
 

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Discussion Starter · #6 ·
Thanks for that, i have done this and all seems ok, its not going to ground and i have 0.2 of an ohm across the wires. This is actually a problem i have inherited, the bike belonged to a mate, he is not mechanically minded and this got the better of him, he had someone strip it for him they found the broken magnets and the damaged stator, i found him a stator on ebay it was old and had been kicking around in someones garage for years but was boxed and had never been on a bike, as i said a local workshop had a clutch basket with magnets intact so this was fitted, this is where i came in, i felt sorry for him and bought the bike from him, he now has got a brand new sportster, anyway, i figured that since i was only getting about a 3rd of the voltage i could have bought by mistake a stator from a later bike that fits on the crank, given that the crank spins about 3 times faster than the clutch basket this would account for the difference in voltage ?????I have been told the stators have the same fitting points. So i ordered the correct part for the bike from the zodiac book, this arriveed and has been fitted but the results are exactly the same, at this point i am loosing the will to live. I am just looking at the clymer book for this model however and i see in the book the stator is bonded, neither of mine have been could this make a difference. Cheers
 

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I dont think the bonding or lack there of, is causing the problem. I am at a loss. This is extremely simple, good stator, good rotor and you have voltage. I assume the stator you put in was for that exact year bike?
 

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Discussion Starter · #8 ·
I trust the bloke i ordered it through but the box came with no part numbers on it so i suppose a mistake could have been made, the one i just got is exactly the same as the one we got from ebay so i had a feeling it was not going to fly from the start, i have voltage just not enough, this is why i thought it was the wrong stator in the first place, cos all it is, as you say is magnets and coils of wire, the only factor as long as the magnets are strong (they are, the clutch really pulls itself on) is the amount of wire in the coils and the speed of the magnets, sadly the old broken stator has been thrown away to i can't take a look.
 

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It's just a coating to help protect the coils. It also helps stabilize the coils from vibration. Electrically it should make no difference.
 

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Are you certain you trust your AC volt meter readings? Have you verified you still can't get a charge to the battery when it's all connected?
 

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Discussion Starter · #12 ·
Thanks for your post, to be honest i have not put it all back together as i stopped at the alternator wires when i saw the low voltage, i have also tried a couple of volt meters. This has me confused, the stator that fits my 89 bike is the same type that fits the later bikes the only visible difference is the length of wire from the stator to the point where it exits the primary case as the later bikes have the stator on the crank, now... as i have said the crank spins about 3 times faster than the clutch basket, so i figured that the windings on the stator would have to be different to account for this, however it has been pointed out to me that even though the clutch basket is revolving slower it has a bigger surface area of magnets that would compensate for this............... Any thoughs anyone, can anyone confirm my theory, as i have bought 2 stators and a rotor, and still not enough volts, the rotor is second hand but the magnets are all there and strong, not sure how strong they are meant to be but there strength pulls the clutch basket on with some force, someone in the USA is selling brand new stator and rotor genuine Harley on ebay for less than half the price i can buy for in the UK this is tempting but i want to find out what is up with the thing and not just throw more money at it. Thanks in advance
 

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The working physics of this alternator design are pretty straight forward, if the magnets rotate directly over the top of the stator poles, you’ll generate measurable AC voltage. To generate enough AC voltage that will equate to a forward charge on the battery (via voltage regulator), you need at least 10 Vrms, and probably twice that for electrical loads.
Sorry, I have no clue why is doesn’t work as it should.
 

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Discussion Starter · #14 ·
Thanks anyway, i have just ordered genuine hd parts from your side of the pond, very cheap compared to uk
 
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