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So, long story short, got an '80 Honda CBX with a ZX-7 alternator conversion. The alternator has a 2 wire connection (unlike

older bikes with separate stator/recreg setups )

Anyone know how to test it? I'm not sure if the alt went bad or the bike has developed a short. Early this season, one of 3 CDI
boxes died. These are no longer available from Honda (there ARE aftermarket replacements which I now regret NOT
using) .Instead, I decided to "upgrade" to a semi-custom Dynatek-based setup . The bike starts and runs but doesn't shut off with the
ignition key. ( Luckily, the kill switch works.) When the ignition switch is turned off- the lights actually get brighter. The low beam blew. So now am wondering if the cdi box demise was caused by something other than old age failure. Seems like there is back-feeding somewhere or a short has developed. Anyone know how to test the alternator? With my test meter set on "20"/direct current, it reads 13.9 with the engine running. Shut the ignition switch (it keeps running) and the meter display changes to "1", but something tells me it doesn't mean 1 volt or it would likely stall, wouldn't it?



thanks in advance
bill
 

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..if you are reading directly from the alternator, then the alternator produces AC current, not DC current (AC = alternating current), and the meter should be on AC not DC. Am surprised when you said 2-wires. The alternators usually have 3-wires and it makes something like 40 VAC (Alternating voltage between these wires, not connected)

….but got the feeling you are talking about the rectifier/regulator not the alternator itself. The R/R produces DC (about 14VDC, on 2-wires).

The alternator is that big round chunk, usually on the left on the crankshaft, but believe the CBX has it mounted behind the cylinders, as the six crank is already too long. What is called the stator is simply the part of the alternator that does not move, the other part is the rotor/magnet driven by the crank, which also acts like fly wheel.
 

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..if you are reading directly from the alternator, then the alternator produces AC current, not DC current (AC = alternating current), and the meter should be on AC not DC. Am surprised when you said 2-wires. The alternators usually have 3-wires and it makes something like 40 VAC (Alternating voltage between these wires, not connected)

….but got the feeling you are talking about the rectifier/regulator not the alternator itself. The R/R produces DC (about 14VDC, on 2-wires).

The alternator is that big round chunk, usually on the left on the crankshaft, but believe the CBX has it mounted behind the cylinders, as the six crank is already too long. What is called the stator is simply the part of the alternator that does not move, the other part is the rotor/magnet driven by the crank, which also acts like fly wheel.



Thank for your input. The reason I mentioned ZX-7 was because it has an alternator with an internal regulator/rectifier (the initial post implies this) , which is why

I asked how to test it. Am assuming it is more or less like testing the output of a separate regulator but still wonder if anyone has done
it as "assuming" isn't always the best idea, even though car alternators and are basically configured the same. If it has an internal regreg, there shouldn't be any A/C voltage coming out of it at all. The usual 3 wire output into a regulator and/or rectifier is internal
to this one.







thanks,
b
 

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The output of an Rectifier/Regulator is what provides most of the electric power of the bike, when running,...and charges the battery. Any factory manual for the proper bike would mention how to test it.

...but in general, the RR produces about 14VDC from about 2,000 rpm, and it climbs with the revs. It should not go past 15VDC. The RR is fed by the three wires from the Alternator, and it only produces power if engine is running and driving the alternator. If engine stops, the alternator does not produce any power, and bike relies solely on the battery.

….I don't understand the part when you said "shuts the ignition key, and it keeps running". If engine does not run, only battery produces energy, if not connected, it goes to 0.
 

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Discussion Starter #5
The output of an Rectifier/Regulator is what provides most of the electric power of the bike, when running,...and charges the battery. Any factory manual for the proper bike would mention how to test it.

...but in general, the RR produces about 14VDC from about 2,000 rpm, and it climbs with the revs. It should not go past 15VDC. The RR is fed by the three wires from the Alternator, and it only produces power if engine is running and driving the alternator. If engine stops, the alternator does not produce any power, and bike relies solely on the battery.

….I don't understand the part when you said "shuts the ignition key, and it keeps running". If engine does not run, only battery produces energy, if not connected, it goes to 0.



Thanks for trying to help and I agree there is a substantial amount of non-understanding involved in this one.

Have a great one..
 

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Hey my late 89 ZX 10 had a self contained alternator . 3 wires are needed Field /grd/output. The field supplies magnetizing current to the rotor via slip rings and brushes. Field current is regulated by a zener diode inside the alternator near the brush holder. The rotation of the magnetic field induces Voltage and current into the Stator. now power is produced, taking its energy from the crankshaft. Current from the stator is passed through a rectifier which converts the AC power to DC and now can be utilized by the battery and electrical system. *Observing polarity apply 12v + through a test lamp and ground. Do you feel resistance while turning the shaft ? Next connect a meter to the output of the alternator (big wire), give the shaft a spin. Did the meter show DC voltage? These are the basics of the modern alternator. Good luck in your endeavor!
 

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If it is a true alternator with internal regulator, then yes should be DC output. The 2 wires could be pos and neg with field wire tied to power internally or positive output wire and ign sw controlled field wire to control output level with unit grounding thru case like GM and most other car alternators., have to see a schematic... Do you have wiring schematics for both bikes?

If this just started, then I'd suspect the alt output and ign coil wires connected together either by a short or other wiring issues so it effectively hot-wired itself. If it's done this since conversion, then something is not wired correctly, if field is not wired to power internally, may need to relocate field wire to keyed source or add a relay in the field wire, so the field voltage is killed with the key off or ??? Alt. output should go straight to battery in most cases. once running, full voltage is on field wire to control output. Some of the one-wire alternators used on hot-rods etc, have some sort of diode (or internal relay?) setup to apply power to the field when running but not bleed current when stopped.

Had a Dodge Superbee blow an intake heat crossover gasket one night, hot exhaust blowing on the wiring loom melted the alt output wire and ign coil wire together so the car hot-wired itself, couldn't shut it off, had to pull the battery cables and then use the choke to kill it. Thanks (I think,,,) for stirring up those memories.
 

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If it is a true alternator with internal regulator, then yes should be DC output. The 2 wires could be pos and neg with field wire tied to power internally or positive output wire and ign sw controlled field wire to control output level with unit grounding thru case like GM and most other car alternators., have to see a schematic... Do you have wiring schematics for both bikes?

If this just started, then I'd suspect the alt output and ign coil wires connected together either by a short or other wiring issues so it effectively hot-wired itself. If it's done this since conversion, then something is not wired correctly, if field is not wired to power internally, may need to relocate field wire to keyed source or add a relay in the field wire, so the field voltage is killed with the key off or ??? Alt. output should go straight to battery in most cases. once running, full voltage is on field wire to control output. Some of the one-wire alternators used on hot-rods etc, have some sort of diode (or internal relay?) setup to apply power to the field when running but not bleed current when stopped.

Had a Dodge Superbee blow an intake heat crossover gasket one night, hot exhaust blowing on the wiring loom melted the alt output wire and ign coil wire together so the car hot-wired itself, couldn't shut it off, had to pull the battery cables and then use the choke to kill it. Thanks (I think,,,) for stirring up those memories.

Yeah the diode thing crossed my mind and I actually have a mid-engine car with a 1-wire GM alternator that uses an external diode to prevent run-on. But this doesn't exactly strike me as a diode issue since shutting the ignition switch off results in not only run-on-

but apparently also enough voltage to fry the low beam make the running lights go VERY bright. My voltmeter was set on 20 and
during "run-on" it went from a little over 13 to "1"-- the signal for "out of range". Gonna pull the bulbs tomorrow and

try again on a higher setting although I'm not sure how that will help. Am still stumped regarding the cause unless something inside the alternator blew but even then it should still shut off, although the kill switch still works...so I have something wrong somewhere. It's somehow back feeding after the key is shut and yes the hot wire connects to the battery/old style main 30amp fuse. Have diagrams for both bikes. Hot wired itself eh? . Handy.



Attached a photo of my car with the 1-wire alt.



thanks for writing-
b
 

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Hmmm,, did the original stator maybe have an ignition winding that got incorporated into the new setup? so it is hot-wiring itself? Also, if the field wire IS shorted to the ignition or other power source through an ignition coil or partial/high resistance short. it would then see a voltage drop at the field when you turn the key off and try to increase output to bring the voltage up. could all be the same problem.



can you send those schematics?
 

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Hmmm,, did the original stator maybe have an ignition winding that got incorporated into the new setup? so it is hot-wiring itself? Also, if the field wire IS shorted to the ignition or other power source through an ignition coil or partial/high resistance short. it would then see a voltage drop at the field when you turn the key off and try to increase output to bring the voltage up. could all be the same problem.



can you send those schematics?

well the original stator has been removed from the bike and there are no remnants. The new alt has a 2 wire pigtail- one red & one black wire. The red wire is

always hot. The black one is switched 12V when the ignition key is turned on. There is no continuity between the two BUT there IS

continuity between the black wire and GROUND at all times -however the black wire harness connection goes to the fuse box and
is used to distribute power to each of the (4) 15 amp fuses so it probably WOULD go to ground eventually, and if there were a direct

short it must be safe to assume a fuse would blow. I must've wired something wrong BUT, with the alt unplugged, everything works as intended. Indeed, it also works as intended as long as the bike
is running, while it is plugged in. When the switch is turned OFF, there must be a back-feed to the black wire or the ignition

would have to shut down. Instead, everything gets power anyhow- too much of it. There is a schematic on cbxworld.com but my bike no longer follows quite a bit of it since the alt and ignition have been changed-


thanks for your help!
b
 

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What is the red wire connected to? Should be going directly to battery...

Also, Need to check the schematics for the bike that supplied the alt. see where the black wire went. I suspect the black wire went through an idiot light or something 1st. They used to do that where the alt. light would ground through the field wire when key is on and not running, then when the alt is putting out, the field had voltage on it so the light had no difference of voltage across it and would go out. With the black wire tied directly to the key-on side of power, the field voltage will be going through the ignition coils and/or lights to ground. And grounding the field wire is how we'd test alternators for full output...

People called me crazy etc when I told them their battery was dead because the dash light indicator bulb had burned out...
 

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What is the red wire connected to? Should be going directly to battery...

Also, Need to check the schematics for the bike that supplied the alt. see where the black wire went. I suspect the black wire went through an idiot light or something 1st. They used to do that where the alt. light would ground through the field wire when key is on and not running, then when the alt is putting out, the field had voltage on it so the light had no difference of voltage across it and would go out. With the black wire tied directly to the key-on side of power, the field voltage will be going through the ignition coils and/or lights to ground. And grounding the field wire is how we'd test alternators for full output...

People called me crazy etc when I told them their battery was dead because the dash light indicator bulb had burned out...

thanks for writing! ost of those wiring diagrams can be pulled from the 'net by just searching for something like "1994 Kawasaki ZX7 Wiring Diagram" then clicking on "Images". Most of the hits the come back are NOT of that but one or more usually ARE.


b
 

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Are you sure the 2 terminals from the alt are going to the right places? If the schematics I found are close, appears one goes direct to battery power and the other to key-on power. Both would/should have full voltage when running. If reversed, it "might" cause strange troubles like you are seeing. Verify which terminal is going where and try to confirm from repair/sshop manuals. Otherwise I am out of ideas..
 
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