XS 500 Black Out

[anveville]

Hi everybody,

It was a long time the XS500 has not had a good run. This morning, I decided to use it. I knew the battery was dead flat, so I jump started the engine. Everything was fine, and the engine was gently warming at idle, when suddenly, a total black-out happened.

The engine stalled suddenly. No light of any kind, no starter, nothing...

I have checked the fuse-box near the battery, everything is fine.

Do you have any idea?

Thanks!

[CrouchyUK]

Remember you need a substantial current to even run these engines.  You have the feed to both coils and the excitation for the generator.  If your battery was flat, then no way will there be enough to charge the battery of even keep it alive at idle speed.

Charge the battery up first- it may also be faulty and not hold a charge now, but you cannot run these bikes with a flat or no battery....

[anveville]

Thanks for your reply.

I'll investigate that way...

[anveville]

I bought a new battery yesterday.

I charged it overnight, and intalled it on the bike.

Ignition, neutral light and oil light are back.

A press on the starter button, the engine fired instantly and stabilized beautifully at idle speed.

Two minutes later, still at idle speed, I switched the road light to make sure everything was fine, and... the engine stalled immediately, in a total black-out again.

No light, no ignition, nothing.

Any idea?

Thanks again!

[anveville]

I bought a new battery yesterday.

I charged it overnight, and intalled it on the bike.

Ignition, neutral light and oil light are back.

A press on the starter button, the engine fired instantly and stabilized beautifully at idle speed.

Two minutes later, still at idle speed, I switched the road light on to make sure everything was fine, and... the engine stalled immediately, in a total black-out again.

No light, no ignition, nothing.

Any idea?

Thanks again!

[anveville]

I have checked this morning...

No change...

I am a bit lost!

[guylr]

 If your battery takes a full charge and seems good then I would check the battery positive and ground cables. Try flexing them with the key on to see if the lights go out. If there is internal corrosion on them they may not be able to carry the current and go open. Makes sure the ground cable to the frame has a good connection and that the wire harness ground is good. Also, it is common for the internal contacts in the main switch to corrode over many years. Try wiggling the key to see if the lights flicker or go out. If that happens the switch can be disassembled to clean the contacts.

Guy 

[anveville]

Thank you Guy for theses ideas.

I have already checked the new battery. It gave 12.6 V after the black out. I gave it a new full charge to make sure the problem is not a new but faulty battery.

That done, I have checked (without dismantling) the wiring at the key switch to make sure there is not a loose connection somewhere. Everything seems fine there (the light did not come back when moving the wires). I have put some contact cleaner in the key switch.

Next step, I shall check the harness, and the ground cable.

A friend of mine told me the problem could also be rodents in the garage...

I continue to investigate.

Thanks again.

[CrouchyUK]

Initially this problem only occurred when you switched the lights on.  Now it happens all the time, so you never have any ignition, lights, etc.?  The reason for losing power when switching some more load on- like lights- is generally a bad earth return connection as already suggested.

You can quickly see where you are losing the 12V.  Test at the main fuse- which is the bottom 20A one.  You should have your 12.6V and more either side of the fuse.  Then switch the ignition on, and you should have 12.6V either side of all the other 3 10A fuses as well, as they are supplied from the ignition switch.  The fuse at the far end of the fusebox from the main 20A fuse is the ignition fuse.

Try also moving the ignition switch to the "Park" position.  The rear light should come on, proving at least that the main feed to the ignition switch is good...

[guylr]

To add something to Crouchy's advice that I have seen many times, inspect the fuse clips carefully. Over time the brass clips loose their spring and don't always clamp the fuse well making for a poor, high resistance, connection. Yamaha used to sell the clips to repair the fuse boxes but I don't think they are available anymore.

Guy

[anveville]

Thank you both for these ideas.

I shall check that.

[anveville]

I sometimes feel... say, silly, dummy...

I spend a couple of hours tracking all the connections, earth and positive, to find that everything was in a rather good nick.

Then I came back to my first check, the fuses. They looked as if they were new, but I took a multimeter to check them correctly.

It happened that the main fuse was not working. It was not blown at the middle, as I would have expected, but broken at an end,  and that was not visible.

I changed it, and the bike fired instantly as usual.

The lesson is... check, and double check!

Thanks again!