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

[peanut]

wow you've got it real easy larry.....

when I t'were young we had to walk 20 miles to work with no shoes and carry all our tools .....

Re the starter motor issue it would be worth finding a bit of electrical cable so you can run some simple bypasses like from the battery to the starter motor for instance .

whereabouts are you exactly / i'm sure there must be a member somewhere near you that can come round and give you some help

 

[Tomterrific]

Hi Larry,

I've dealt with similar problems. I carry a couple of wires with small alligator clips on the ends. These are great for bypassing the entire electrical wiring and switches. I hook one end to the positive of the battery and the other to the hot leads to the coils (brown?). The negative ground I run to the engine. Of course this is just to get the engine running in an extreme situation and only the kickstarter is used. However, if the bike runs fine with these simple jumper wires then you know for sure the wiring or a switch is bad.

If I had to guess, I'd say the negative ground wire is the one that is giving problems. Once the ground goes everything stops working. Just to make sure, the battery box is electrically isolated and the ground needs to go the the frame/engine. The safety relay is a bit of Yamaha mischief best bypassed.

Tom

 

[ANLAF]

I have the smallest workshop in the world - I have to push my bike in there diagonally, but at least it is where I can see it and get to it. If I have any more tips, larrynyc, I'll make sure I take into account those three flights of stairs and the limited resources.

Anlaf

 

[larrynyc]

Got some mini alligator clips from the hardware store, I'm going to try to bypass the safety relay. Does anyone know which color wires I have to link together on a 1975 "B" model? When I try to look it up, all I get info for later models which has a different safety relay. Thanks

 

[peanut]

There should be 4x wires going to your safety relay (SR). Two of them should be red/white one should be black (chassis ground) and the 4th should be yellow.

The yellow wire and the black wire comprise the safety relay switch
The two R/W red white wires are the ground wire return from your starter solenoid. The safety switch basically connects or disconnects the 2x R/W wires together allowing the starter solenoid to earth (ground)

Ok so all you need to do is to pull off the connector to the SR.

Take a short piece of wire 2" or so at least as thick as the R/W wires and push the two bare ends into the electrical connector R/W terminals on the loom connector connecting the 2x R/W wires together thus bypassing the SR.

Now try the starter

 

[ANLAF]

I can't wait for larrynyc - the tension is unbearable. Will it fire?

Anlaf

 

[larrynyc]

So today I fashioned a very solid bypass for the safety relay, to connect the red/white wire to the red wire. The bike fired right up! Rode it towards home.... and then kaput. Died about four blocks from my place. Same problem as before--can't kickstart it, and it won't respond to the start button at all (there is no sound). The headlight, turn signals, brake light and horn all work and are nice and bright. But the bike just sits there. So I guess the starter relay wasn't the issue.

I'm thinking my next step may be to replace the entire wiring harness. Or is that overkill?

EDIT: I mistyped the relay, I meant "safety relay". Edited for clarity.

 

[TwoManyXS1Bs]

Okay, larry, you've got it narrowed down to the safety relay (not the starter solenoid), the "run" switch (atop the right handlebar switch), and the wiring in between. Next is to do Peanut's bypass trick, in post #25. You can leave that bypass in place, forever if you want, just don't bump the starter button while the engine is running. If the problem reappears, then it's time to check the "run" switch wiring inside the headlight shell, and/or the "run" switch itself...

 

[peanut]

just don't bump the starter button while the engine is running. .

well I guess you'd only do it the once

its beginning to sound like 2x seperate issues don't you think ?

Odd how it always seems to fail when it gets to operating temperature ? funny you should mention the wiring in the headlamp bucket.... someone had a run problem last week that turned out to be a short in the headlamp

 

[larrynyc]

Okay, larry, you've got it narrowed down to the safety relay (not the starter solenoid)

Whoops I mistakenly typed "starter relay" but I meant "safety relay" (it was late when I typed it. I edited it now for clarity).

So I did Peanut's bypass trick for the safety relay — Here's a pic of how I bypassed the safety relay:
http://i.imgur.com/WbQCQes.jpg

After doing what was shown in the picture, the bike started right up, but unfortunately it died after a few minutes, four blocks from my place. No dice, it's definitely not the safety relay.

I assume my next aim should be the starter solenoid. What's the best way to isolate or bypass the solenoid?

 

[peanut]

its difficult to know whats going on with your bike larry. Your description makes it sound like you have 2x seperate issues going on that may not necessarily be related.

you have an intermitant starter motor which could be the safety relay or the loom wiring or bad connections in the loom or starter switch .it could also be dirty comutators inside the starter motor or worn brushes or even a slight oil leak into the starter motor.

When the starter motor doesn't work will it start on the kick start ?

Then you've got a cutting out issue when the motor gets warm.

It sounds like the motor runs fine when it is running so I'm going to assume that it is probably not an issue with your carbs (although it could be a low fuel supply issue )

If the engine cuts out dead... i would tend towards it being an electrical or grounding issue or one of the electrical switches or components because if it was fuel starvation I would expect the engine to cough and splutter a bit before cutting out .

Have you checked that your fuel tank is getting vented ? if the filla cap is airtight you'll get a vacuum forming in the tank after a while .

 

[peanut]

Whoops I mistakenly typed "starter relay" but I meant "safety relay" (it was late when I typed it. I edited it now for clarity).

So I did Peanut's bypass trick for the safety relay — Here's a pic of how I bypassed the safety relay:
http://i.imgur.com/WbQCQes.jpg

?

not sure why you connected the red wire to the red/white wire ?

What I intended was for you to join together the two wires in the electrical connector

What you did was to connect a new 12v feed to the connector which is confusing things somewhat.

could you tell me the colours of the 4x wires in the block connector please Larry.

 

[larrynyc]

not sure why you connected the red wire to the red/white wire ?

What I intended was for you to join together the two wires in the electrical connector

What you did was to connect a new 12v feed to the connector which is confusing things somewhat.

could you tell me the colours of the 4x wires in the block connector please Larry.

I wired it that way because the relay's block connector had only three wires in it--Black, Yellow, and Red. The space where a fourth wire would go was empty. The relay also had a separate single red/white wire with a female bullet connector.

 

[larrynyc]

PS Here's the wiring diagram for my bike
http://thexscafedotcom.files.wordpress.com/2012/01/75-xs650b-wiring-circuit-diagram-2.jpg

 

[peanut]

ahh sorry larry I was referring to a slightly later schematic. Your bike has a different wiring layout than I thought.

Let me have a minute or two to digest the schematic ok

Right . your Starter relay (SR) is effectively a heavy duty electrical switch, what we would normally call a 'Solenoid' on a car.
it contains a switch and an activating coil
There is a constant direct 12v+ live feed to the SR (Red wire) Its live even with the key switch turned off.

The other red wire on the SR is switched live and goes to the starter motor . When you press the starter button an electrical current passes through the relay coil which energises the coil thus closing the integral switch which connects 12v+ to the starter motor.

Blimey thats hard to describe.

What you need to check is that you have good clean connections on your battery and on the starter relay connector and the starter motor particularly the ground for the starter motor.

First try connecting a battery jump lead from the battery - negative (black ground) terminal to the ground terminal on the starter motor. This will bypass the existing ground connection . See if there is any improvement in the starter motor operation.

To bypass the starter relay and the starter switch and test the starter motor ,all you need to do is to connect one end of a heavy duty wire to your + positive terminal of your battery and the other end briefly touch the red wire terminal on your starter motor which should cause your starter motor to turn over .
Make sure you are in neutral obviously and the main switch is off unless you want to try start the engine.

If that works every time then the problem likely lies in the starter switch, safety relay, stop switch, solenoid and all the associated wiring.

 

[nj1639]

2many mentioned the kill switch....would be good to confirm that it's good and check the bushing rubbers in the headlight bucket to make sure they're positioned properly and no wires are being cut on the metal headlight shell. Costs nothing to check.

 

[peanut]

yes your right the kill switch could well be the problem but trouble is if we jump about all over the place testing stuff randomly its easy to miss stuff and it doesn't always tell you anything.
I was thinking to check the starter circuit first before tackling the running problem as the two issues may not be related.

If the starter motor works every time with the bypass then we can be pretty sure we can eliminate the starter motor as causing the starting issue. Sequential process of elimination hopefully reduces the stuff you have to check

 

[TwoManyXS1Bs]

I've been studying the `75 XS650B schematics available online, and the depicted wiring relationship between the kill switch and safety relay doesn't make sense. If I understand correctly, the XS bikes had paired model similarities, i.e., 70-71, 72-73, 74-75, 76-77, 78-79. I've also read that the `74 and `75 have similar wiring. Here's a `74 wiring diagram that shows a different relationship between the kill switch and safety relay, which makes sense to me. An important feature depicted here is that the 'brake warning' light should illuminate when engaging the starter, and if it doesn't, there may be a failure in the kill switch and you need to check the blue/white and red/white wiring sections.

 

[peanut]

argh thats a horrible schematic

The problem with that type of schematic is that it doesn't show the internal wiring and connection arrangements within the components themselves.
For example the coil connections within the starter relay so for a novice its almost impossible to troubleshoot from that kind of schematic.

I know exactly what you mean about the start/kill circuitry not making sense. It seems to me to be over-complicated.
Did you spot the diode in there ? god knows what that is for ....ah it is probably to prevent reverse polarity when the kill switch is operated ?

I have been meaning to extract various circuits from these schematics to show each operational circuit seperately but haven't found the time yet.

 

[TwoManyXS1Bs]

argh thats a horrible schematic

Agreed, but it's the only 'factory' schematic I could find.

The problem with that type of schematic is that it doesn't show the internal wiring and connection arrangements within the components themselves.

Agreed, again. The factory schematic is more for component replacement. I like jayel's schematics, better for troubleshooting. You ought to see my factory GM schematics, like they don't want you meddling in there.

For example the coil connections within the starter relay so for a novice its almost impossible to troubleshoot from that kind of schematic.

And to understand theory of operation.

I know exactly what you mean about the start/kill circuitry not making sense. It seems to me to be over-complicated.

I think RG has some choice words here...

Did you spot the diode in there ? god knows what that is for ....ah it is probably to prevent reverse polarity when the kill switch is operated ?

Bingo!

I have been meaning to extract various circuits from these schematics to show each operational circuit seperately but haven't found the time yet.

An admirable project. Got enough medication?

Does anybody have a copy of the actual factory schematic for the `75?