khales
XS400 Enthusiast
Hey guys. I'm trying to test the stator on my 77 right now. What is the best way to test it and what color are the Stator wires coming out. Sorry bout the ignorance here. I'm by far an electrical expert.
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Stator
- Thread starter khales
- Start date
khales
XS400 Enthusiast
Also, What is the correct voltage that it should be putting out?
3 white wires output, volts should be measured at the battery terminals circa 13 - 13.5 volts @ 3 k revs this is with a fully charged and functional battery.
suspect voltage reg if low.
suspect voltage reg if low.
motoman1979
XS400 Member
Hey Drewpy, I thought that the output was supposed to be more like 14.5V? When the voltage regulator is not functioning well, does it usually present as allowing too little Volts or too many volts to the battery. Or could the low voltage output also be a function of a damaged stator?
Thx
Thx
14.5v at 5k revs
if its a electro mechanical VR it can be adjusted. I'd 14.5 is on the limit for lead acide batteries too.
BryceVR
XS400 Member
The standard for a static good battery is about 13.26 strictly. Therefore a charging unit must supply more than this. Typically at over 3800rpm an XS unit will supply over 14.5V. This figure is supplied after a rectifier circuit that uses the 3 phase pulses from the alternator and gives a DC output to a regulator which stops the system from over supplying and therefore exploding batteries. The over supply of voltage is dumped to ground through filters hence the heat sinks on most Rec/Reg units, this process generates heat.
So, we have 2 circuits a rectifier which chokes the return on an AC supply to become DC (which we need) and is essentially a diode, and a regulator which stops our high speed wheel-standing antics dumping more power to the system than it can cope with.
Normally any auto system is regulated to about 14.5V DC.
In an excited system (Ours) the magnet portion of the generation is supplied by a separate regulator which excites coils (electromagnets) and as an aside there must a voltage present before the generation system can work. Hence we see Caps or small capacity battery systems in stripped down bikes. A nearly flat battery can supply enough to get the system going but no battery, no start. You need a small voltage to give the coils some capacity to generate a magnetic field. That's why they're called "field coils" .
PMA or Permanent magnet alternators, use a set of magnets set into a flywheel (on the crank) which excite the coils and give us a charge. Downsides, a few kicks to get going the unit requires a few kicks to get enough power to fire the coils, less efficient, a real bitch to convert, no battery (you can use a washing machine capacitor if you want) but no lights unless you're running or have a battery. Up side, no extra circuit to wire and no need to disable the coil when parked.
All systems have 3 primaries coming from the alternator.
A Field coil system has one extra to run the Field coil. Usually the field coil runs to earth so just a regulated voltage will get it going (I've used my R/C plane batteries to get the bike running so in a real push you could use some AA's in a pack if it came down to it.)
See what you think and get back to me.
I'm doing a "SO COOL" LiFePo4" system thats works a treat and the batteries weigh about 400 Gms with a weight saving for the electrics of over 6 KG.
So, we have 2 circuits a rectifier which chokes the return on an AC supply to become DC (which we need) and is essentially a diode, and a regulator which stops our high speed wheel-standing antics dumping more power to the system than it can cope with.
Normally any auto system is regulated to about 14.5V DC.
In an excited system (Ours) the magnet portion of the generation is supplied by a separate regulator which excites coils (electromagnets) and as an aside there must a voltage present before the generation system can work. Hence we see Caps or small capacity battery systems in stripped down bikes. A nearly flat battery can supply enough to get the system going but no battery, no start. You need a small voltage to give the coils some capacity to generate a magnetic field. That's why they're called "field coils" .
PMA or Permanent magnet alternators, use a set of magnets set into a flywheel (on the crank) which excite the coils and give us a charge. Downsides, a few kicks to get going the unit requires a few kicks to get enough power to fire the coils, less efficient, a real bitch to convert, no battery (you can use a washing machine capacitor if you want) but no lights unless you're running or have a battery. Up side, no extra circuit to wire and no need to disable the coil when parked.
All systems have 3 primaries coming from the alternator.
A Field coil system has one extra to run the Field coil. Usually the field coil runs to earth so just a regulated voltage will get it going (I've used my R/C plane batteries to get the bike running so in a real push you could use some AA's in a pack if it came down to it.)
See what you think and get back to me.
I'm doing a "SO COOL" LiFePo4" system thats works a treat and the batteries weigh about 400 Gms with a weight saving for the electrics of over 6 KG.
motoman1979
XS400 Member
wow...thanks guys, that is great info. I'm starting to piece together and make sense of my charging system. All that said...I think that I've narrowed it down to the fact that I have a faulty stator. I measured the AC output at the plug and I get a steady 10volts per wire at idle. When I crank the throttle up to 3-5000k rpm I only get a jump in AC output up to 12.5V which I don't think is sufficient? Correct me if I'm wrong? I get the same numbers with the voltage regulator plugged in versus hardwiring the field coil to the battery and bypassing the voltage regulation portion of the whole circuit. So...I think I need a new stator. It looks like the late 70's XS 400 have a different stator than the early 80's due to the addition of one more wire coming off the stator which leads to the headlight relay. Once the bike is running it trips the headlight relay connecting the circuit of the headlight to DC power and thus turning it on. Do you guys think that the early 80's XS400 stators would work in this system, even though they are missing the fourth wire? Could I, in place of that 4th wire, bypass the headlight relay and hardwire in the headlight and use a simple on/off switch to supply power to the headlight. Therefore keeping the headlight off while the bike is starting and then turning it on while running? The reason I ask is that I have access to an old early 80's XS400 stator but have not been able to track down the late 70's one!!! thx
mine had a 4th wire in, but it terminated in the rubber ferrule. You can bypass it and remember to switch the lamps on like we do in the UK 
motoman1979
XS400 Member
Interesting...so there was a fourth wire coming off the stator. Do you think that, if I wanted to, I could solder into that terminating wire and use that wore into my headlight relay? Other than the 3 vs 4 wire difference....do you know if there is anything else different between a 1980 vs 1979 model Xs 400 stator? I think that the field coil is the same part number.
Or....instead of getting a used stator, do you think I'd be smarter to get my current stator rebuilt?
Thx a lot, appreciate the advice!!
Or....instead of getting a used stator, do you think I'd be smarter to get my current stator rebuilt?
Thx a lot, appreciate the advice!!
BryceVR
XS400 Member
I need to clarify and make an apology.
I had assumed, and to a degree was correct by supplying a constant field coil voltage and using a standard reg/rec that I'd be OK. Yes I would, but not ideal. It would cause the alternator to constantly supply a high voltage that would then have to regulated
Ideally a separate feed is fed to the field coils through regulation by switching the field coils on or off. This there fore means that the output from the alternator is regulatated and there is no dump to earth and wasted power.
Of course this means a slightly more complicated system but I am working on some very elegant options at the moment that may appease my earlier misinformation. (not wrong but not correct)
I had assumed, and to a degree was correct by supplying a constant field coil voltage and using a standard reg/rec that I'd be OK. Yes I would, but not ideal. It would cause the alternator to constantly supply a high voltage that would then have to regulated
Ideally a separate feed is fed to the field coils through regulation by switching the field coils on or off. This there fore means that the output from the alternator is regulatated and there is no dump to earth and wasted power.
Of course this means a slightly more complicated system but I am working on some very elegant options at the moment that may appease my earlier misinformation. (not wrong but not correct)
BryceVR
XS400 Member
You can give a filament light anything... AC , DC, or static and it will light. In rudimentary systems (Ride on mowers for example) the lights run from the AC feed un regulated so they can only be on with the the engine running and of course get brighter when the engine revs up.
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BryceVR
XS400 Member
Made this cool custom mower last year and had to re-invent some kit for it to be perfect.
MP3, Bluetooth and a nice paint job, extended the bonnet to hold the bigger engine and to top it off, it cuts the grass really well. They use a different charging to most and a different engine presented challenges but I got it sorted fairly quickly.
My point is that sometimes you have to move away and re-invent.
MP3, Bluetooth and a nice paint job, extended the bonnet to hold the bigger engine and to top it off, it cuts the grass really well. They use a different charging to most and a different engine presented challenges but I got it sorted fairly quickly.
My point is that sometimes you have to move away and re-invent.
