1980 yamaha xs650 no electricity (rotor rewound thread repost)

Skfork

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Hello, so i just picked up this 1980 xs650. It kickstarted fine, and then the battery died, ive replaced it and still no power. Was thinking stator but a few people have said thats unlikely, and pointed me towards checking for grounding out somewhere.

I checked the battery strap to the bike, and when i go from end of strap to where it bolts on im reading .5 ohms, but when i go from end of strap directly to bike frame im reading infinity, so is that where its grounding out?

Here are pics and thanks for any advice!
 

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The title says rotor rewound so assuming checked
To battery there are 2 wires minus going to ground where 0. 5 can be OK
The other is positive and what it reads depend on fex ignition Switch position

Fuses checked ?
If it was me suspecting bad ground I would pull one more wire from minus to engine casing somewhere for testing.

Please provide more info a bike that started and charging would normally not stall unless a big problem somewhere
Is it a stock electrical system.

Does a charged battery go flat ? after how long ??

Fluke meters have good reputation
 
You made it back from duty!

So if we're talkin' battery positive cable to where it bolts on (starter terminal?) @ .5 Ohms, that's ok - it's just reading normal resistance through the starter motor. And infinity to frame is good too.

Battery negative cable to frame and engine case, we want 0.00 Ohms.
 
The title says rotor rewound so assuming checked
To battery there are 2 wires minus going to ground where 0. 5 can be OK
The other is positive and what it reads depend on fex ignition Switch position

Fuses checked ?
If it was me suspecting bad ground I would pull one more wire from minus to engine casing somewhere for testing.

Please provide more info a bike that started and charging would normally not stall unless a big problem somewhere
Is it a stock electrical system.

Does a charged battery go flat ? after how long ??

Fluke meters have good reputation
It just says rotor rewound because i got some advice from people on garys rewound rotor sale page and wanted them to find me

I just picked up the bike. When i got there it kickstarted and ran fine, but when we killed it the guy left ignition on so running lights and the battery died. Now ive used a couple different new batteries and still no power, cant start it, no lights
 
It just says rotor rewound because i got some advice from people on garys rewound rotor sale page and wanted them to find me

I just picked up the bike. When i got there it kickstarted and ran fine, but when we killed it the guy left ignition on so running lights and the battery died. Now ive used a couple different new batteries and still no power, cant start it, no lights
That sounds like it may be a blown main fuse that should be a 20amp fuse in fuse box or a disconnected wire at the starter solenoid (battery side)

If it did blow the main fuse, there's a couple more checks advisable before replacement.
 
You made it back from duty!

So if we're talkin' battery positive cable to where it bolts on (starter terminal?) @ .5 Ohms, that's ok - it's just reading normal resistance through the starter motor. And infinity to frame is good too.

Battery negative cable to frame and engine case, we want 0.00 Ohms.
Im not 100% sure which is which, but im pretty sure you mean this is the battery positive cable, which reads infinity no matter how i read it
 

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Im not 100% sure which is which, but im pretty sure you mean this is the battery positive cable, which reads infinity no matter how i read it
Yep, that should be the battery side positive cable. Is the ring terminal pictured from the solenoid end?
 
Could have burnt out the coil. Worst case is the TCI unit. Not ssure if leaving the ignition on that long will kill the TCI but not grounding the plugs when turning the engine over will
 
Could have burnt out the coil. Worst case is the TCI unit. Not ssure if leaving the ignition on that long will kill the TCI but not grounding the plugs when turning the engine over will

Believe there would still be lights on a stock wiring .( Which is uncertain if there )
Unless it fries to a slam dunk grounding in coil

couple different new batteries and still no power, cant start it, no lights
 
That sounds like it may be a blown main fuse that should be a 20amp fuse in fuse box or a disconnected wire at the starter solenoid (battery side)
You sir are a genius. I was unable to find the main until now, and lo and behold its blown. Such a simple fix thanks a lot!
 
You sir are a genius. I was unable to find the main until now, and lo and behold its blown. Such a simple fix thanks a lot!
Hold On! bout both lol

Good idea to find out why the main fuse blew. It could be random and replacement good to go. But if it blows another or ya want to avoid that - there's a couple more checks.......up to you
 
Hold On! bout both lol

Good idea to find out why the main fuse blew. It could be random and replacement good to go. But if it blows another or ya want to avoid that - there's a couple more checks.......up to you
Yes Sir and have spare fuses with you if you go somewhere
 
I think that ring terminal was the solenoid end of the battery cable, it needs a good cleaning and ya can reconnect it.

So on the main fuse, lets test resistance to bare frame/ground on each side of the fuse clips: should be infinity. Good to look at other fuses in there too and because the ignition coil is susceptible to key-on periods (like Skull said), lets put the kill switch (R handlebar) to the run position and test resistance to bare frame ground on the fuse clips of the red/white wires' 10amp fuse.

One more test when the above is done......
 
I think that ring terminal was the solenoid end of the battery cable, it needs a good cleaning and ya can reconnect it.

So on the main fuse, lets test resistance to bare frame/ground on each side of the fuse clips: should be infinity. Good to look at other fuses in there too and because the ignition coil is susceptible to key-on periods (like Skull said), lets put the kill switch (R handlebar) to the run position and test resistance to bare frame ground on the fuse clips of the red/white wires' 10amp fuse.

One more test when the above is done......
Checked resistance on the fuses, all good. Im not sure how to test the ignition coil, is that the same thing as the ignition unit?
 
If you didn't get any continuity (low resistance) to ground on the red/white wire I think we're ok for the current concern of blowing fuses. I don't think the ignition coil is involved in that

One possible culprit for main fuse blowing, non-charging and battery draining is the rotor (field coil):

You can measure the resistance between the slip rings by removing the two screws holding the round left side cover on the engine and measuring resistance across the brush screws at the 9 O’clock position on the stator housing – should be 5-6 Ohms – and then measure resistance between each screw to bare engine case: should be infinity.

stator housing.jpg
 
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If you didn't get any continuity (low resistance) to ground on the red/white wire I think we're ok for the current concern of blowing fuses. I don't think the ignition coil is involved in that

One possible culprit for main fuse blowing, non-charging and battery draining is the rotor (field coil):

You can measure the resistance between the slip rings by removing the two screws holding the round left side cover on the engine and measuring resistance across the brush screws at the 9 O’clock position on the stator housing – should be 5-6 Ohms – and then measure resistance between each screw to bare engine case: should be infinity.

View attachment 238161
I haven’t done this yet, but im wondering. With it being fine until the battery was drained, could it just have been the battery dying and then trying to start it with a dead battery that blew the main? I think i read about that in another forum?
 
It's possible....

By testing the main fuse clips, you've kinda eliminated a dead short circuit in the wiring from battery to key switch. Since other fuses didn't blow it further eliminates some other causes. The rotor having a short is just a possibility - perhaps a little remote. Keep a spare in your pocket for a while and if it blows again soon, unplug the rectifier/regulator combo (8pin connector around the battery) and head straight to safe quarters.

On a new to you old bike, it's a good idea to clean all the wiring connections too. When ya have time; not pulling duty and chasing 'ku'u poʻo ;):jk:
 
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