1975 XS650 dies after 10 minutes warm. Doesn't start until next day

[larrynyc]

Wow, this bike seems to have some design quirks in the wiring for sure! I have been really busy at work so I haven't been able to get to the bike in the daytime so I can see what I'm doing. The good thing is, I pushed it home so no more mile-long walks and subway trips.

I found this schematic (PDF), maybe this will help?

http://thexscafedotcom.files.wordpress.com/2011/04/xs650b-manual-chapter-6.pdf

PS: What's that "fluster" relay in this diagram? That's gotta be a typo!

 

[grizld1]

Flasher relay (turn signals).

 

[TwoManyXS1Bs]

I believe that 'fluster' on the schematic is a freudian slip. The schematic on pg 137 is a mess, the depiction of the starter relay system is goofy, and the 'kill' switch comes off the taillight feed, and doesn't even show switching off the coils. No wonder folks are confused by this system. The localized schematic on pg 139 is much better, just needs to be spread out a little, with longer color-labled wires. The theory of operation paragraph to the left explains it well. Larry, this will be your go-to page...

 

[larrynyc]

One question: Where's the ground terminal for the starter motor?

Is it here (not my bike but I found this pic):
http://i.imgur.com/ZIVxrRF.jpg

 

[larrynyc]

Ha, yes I'm definitely flustered

 

[ANLAF]

That's the neutral switch - when connected it indicates when the bike is in neutral.

Anlaf

 

[larrynyc]

Update: I bit the bullet and ordered a new wiring harness from Mike's XS. It just arrived today so I'll be putting it in tomorrow.

 

[larrynyc]

Well, I have good news. The mystery is solved.

When I opened the headlight bucket to inspect the wires, everything looked fine. Until I was about to push the handlebar wires out; I felt a roughness in a wire. I twisted the clump of wires upsidedown, and lo and behold — a heavily frayed and burned-looking wire:

After checking out the wiring diagram, it turns out that wire goes directly to the kill switch.

So I did a careful repair on the wire with some donor wire and a soldering iron. I taped and sealed the repair with two layers of heat shrink tubing. I rode around the bike in Saturday evening heavy stop-and-go New York traffic for an hour and it never died! I think it's safe to say the problem is solved!

I do have another issue but it seems separate; the left coil seems to not fire once it's warm. But I'll figure out that one later. At least the bike won't die.

Thanks to everyone who helped on this thread.

 

[5twins]

Not working once hot is a common way coils fail. I think you have a bad coil. You could test it by swapping the coils side to side to see if the problem switches cylinders. If it does, the coil is bad. If it doesn't, there's a problem in the wiring to the coil on that side that stopped firing.

 

[TwoManyXS1Bs]

Not working once hot is a common way coils fail. I think you have a bad coil. You could test it by swapping the coils side to side to see if the problem switches cylinders. If it does, the coil is bad. If it doesn't, there's a problem in the wiring to the coil on that side that stopped firing.

Yes, there's a reason that 'kill switch' wire toasted. You're not done yet, a bad coil may have drawn too much current, caused wire overheating, may have cooked wiring elsewhere, too. Pull the tank and check the bullet connectors and sockets that feed power to the coils...

 

[peanut]

thats great news larry well spotted.

Just glad you have got it running at last even if there are other issues.

 

[LiveSlowDieWhenever]

Well, I have good news. The mystery is solved.

When I opened the headlight bucket to inspect the wires, everything looked fine. Until I was about to push the handlebar wires out; I felt a roughness in a wire. I twisted the clump of wires upsidedown, and lo and behold — a heavily frayed and burned-looking wire:

After checking out the wiring diagram, it turns out that wire goes directly to the kill switch.

So I did a careful repair on the wire with some donor wire and a soldering iron. I taped and sealed the repair with two layers of heat shrink tubing. I rode around the bike in Saturday evening heavy stop-and-go New York traffic for an hour and it never died! I think it's safe to say the problem is solved!

I do have another issue but it seems separate; the left coil seems to not fire once it's warm. But I'll figure out that one later. At least the bike won't die.

Thanks to everyone who helped on this thread.

So nice to read a thread with resolution. Cheers!