Field coil

freebird01

freebird01

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So as with most of us here im chasing electrical gremlins.... if i look on a diagram i should be able to jumper the field coil green and black wires directly to the battery do do the razor blade trick....but when i do it pops the main 20amp fuse....thoughts?
 
I got to check the resistance in the field coil...the stator is shot....im showing 1.5 ohms across all legs even after replacing the three white wires

Btw its an 81 xs400s
 
sounds like the stator, accept.... if you are blowing the main fuse you either have a short in the Field coil wiring, or you are connecting the meter to the stator coils. with a current draw of 20A your resistance would be 0.725 Ohms (R=V/I or R=14.5/20). with 4 ohms you should only havfe about 3.6A draw (I=V/R or I=14.5/4). Also, I hear the term short used universally to mean "electrical problem". In fact a short is a condition where two conductors are connected that shouldn't be. I think that you may have a pinched wire that is making connection to ground in the Feild Coil circuit.

On the oother hand the calculated resistance is about what you would want from your stator coils (a little less because I used 14.5V in the calc, but...). Could you be hooking up the wrong coil to the battery?

Just my 2 cents: I think you should check the field coil wires closely (by tracing and with a meter) even if you do have a bad stator.
Good Luck!
 
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I know alot of people think the stator is shot, once you pull out the stator, and look at it, its just the wires. With that said, there are a few of us looking at the Tech section, thinking of upgrading to whats posted in the tech section.

I think its listed right next to the "Drewpy Re-Wire" Which is highly recommended reading. Shoot, I am going to go and double check too. Magnectic something or other. right after I post this :D
 
I did pull the stator and field coil... i did replace the three white wires going to the stator. I did check the stator with an ohm meter seperate from the bike... 1.5ohms across all legs. with .72 +/- 10% being the target its way out of spec... = junk

but what has me confused is the field coil. its basically an electro-magnet. so if you connect the black wire to ground and green to positive then if its good it should excite and thus hold a razor blade to the case...

in my case that doesn't happen. as soon as i touch the jumpers to the wires going to the field coil the main fuse blows. Would a fried regulator/rectifier cause this? I did it with the field coil plugged in....maybe i should try it with it unplugged?
 
Hmmm... I'll look at the schematic when I get a chance, but you're best bet is always to remove oeverything else from the componet you are checking. Ground (-batt terminal) is fine to leave connected, positive should be removed from everything else and then jumped to the + terminal. If you are doing this it shouldn't be the regulator or the rectifier. Important to remember though that an electro magnet is just a coil of wire. if it is damaged and a portion of the coils are shorted (bypassed) then the resistance reading would be low and current goes high. I beleive the field coil should be 4 ohms. What does yours read?
 
http://www.xs400.com/forum/showthread.php?t=9480 Okay, I was looking for my VR info, I know I did a thread about it. I know the previous thread got close. You know when you have a charging issue, it usually all the same 3 things. Recifiers don't usually go bad, but then you hear about an older one that is adjustble. VR Voltage regulators do go bad. I went with the Autoparts store, With associated Pigtail. (get the pig tail it will save you a nightmare to comeup with a waterproof solution for the connections.

I found it!!!!
http://www.xs400.com/forum/showpost.php?p=88162&postcount=72
That thread is "Charging Sys. I am going to try to move those photos into my album so its easier for me to find next time. That thread went 73 post.

napa has their flavor as well, MPE VR38SB
Orielly Auto BWD Select R296 Both have the same footprint. I wouldn't mind downgrading to a smaller one, if anyone knows something smaller out there.
http://www.napaonline.com/Catalog/CatalogItemDetail.aspx?R=MPEVR38SB_0164710204
 
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i did pre-emptivly purchase a ESR350 reg/rec from OEM cycle. figure it will be the cleanest way of killing two birds with one stone. what stinks is the bike only has 6200 miles on it (still original chain/sprockets, tires...etc!!!)

i have carb issues I'm also working through but that's for another thread and another time. I bought it as a non running clean bike and hasn't really seen the road yet (a few passes up and down my alley is it)

the harness hasn't been altered or cobbled in any way so thats a plus...hell the original tool kit is STILL in the pouch under the seat behind the tail light.
 
I did the same thing.(bought a 2in1 vr/Rec) I had to change the connector wire color pin out did not match my bike's pin out. One wire onthe connector did not connect to a populated connector point. when I called the support guys, they said that model is fine for my bike, then the VR part didn't work. so I did what any of would have done, The got the BWD thing, and move on. I am sure I posted what that was. Maybe I will play with that once I get the new chain on.
Tobie
 
well looks like i got a problem in the harness somewhere.

field coil ohms out at 3.9-4.0.... unplugged jumpered to a battery and it will hold a razor blade....ugh...i hate chasing electrical gremlins
 
What is your primary concern now? Why do you think there was something wrong with the field coil?

Something I did when I was working on my charging issues, every connector, I took a piece of sandpaper, and cleaned up every possible connector. ditto on the ground spots.

Stator/Field coil up to first connector, then the jumper portion to the rear of the air filter, Then the connectors to the VR and Rectifier, The relays, I found some dialectic grease for added protection of the brass on brass connections. Since my problem was between the battery and the charging system, got the ignition relay. IE I did not worry about the tail lights/headlights stuff, except for may the ground if there is one there. Then while playing with all those, I did a resistance check to the next connector from there, and double checked for it being grounded out if its not suppose to be grounded. (I had false positives on the turn signal loop)

Good luck
 

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