Safety relay question

[lil2lo]

Hi there,

Been a long time since I've been here, time flies...
So I have a question about the safety relay. I have a XS650 chopperish thing that has a very simplified wiring harness. When I bought the bike it was already in this state so I don't have any spare parts. The bike is kick only and I ridden it like this for 6 years. But I'm getting a little older and the comfort of an electric starter is lurking. So I'm collecting all the needed parts. I want to wire it as simple as possible with a hidden starter button. I do like the safety feature of a safety relay in case I accidentally hit the button or the switch has a short. So I need a safety relay, but it seems there are no new ones/reproduction on the market. Maybe I can find a used one, but I don't really like using a 45 year old electrical part and the thing is big too...
Are there maybe universal starter relays with a cut off function build in? Or other new universal safety relays? I did some searching, but it seems it's not a very common part. All the help is welcome.

 

[Rasputin]

You could wire the starter relay feed or ground through a brake light switch fitted into the clutch cable.
This makes sure you have the clutch pulled in before the starter will engage.I had this system on my Velocette Venom with an Alton starter.
Brake cable switches were fitted to some 80s Triumph and BSA models.

 

[xjwmx]

If you want to keep the starter from being engaged if the motor is running, get an automotive relay and run the starter button through the normally closed (NC) contacts. Connect the yellow wire from the generator to the relay coil. That's basically how the original works so it should work. Make sure the coil is spec'd to operate at 6 volts, because that's all that's guaranteed on the yellow wire.

 

[gggGary]

Need to use a 6 volt AC relay.
But really, Why? Afraid you won't NOTICE the XS650 is running? Few if any cars had a starter lockout, you ever accidentally start a running car?
Even if you do hit the starter not much bad is going to happen.
I had starter run on issues with the relay removed, but no others have reported that issue.
That's why Yamaha put in that relay not accidental restarts.

 

[xjwmx]

Few if any cars had a starter lockout, you ever accidentally start a running car?

That's a good point. I always thought it's main purpose was to help disengage the starter as soon as the motor started, and it's presence made me think it was necessary due to design (or component strength, etc)

 

[Jim]

Need to use a 6 volt AC relay.
But really, Why? Afraid you won't NOTICE the XS650 is running? Few if any cars had a starter lockout, you ever accidentally start a running car?
Even if you do hit the starter not much bad is going to happen.
I had starter run on issues with the relay removed, but no others have reported that issue.
That's why Yamaha put in that relay not accidental restarts.
View attachment 232964

Since it's a bendix style engagement system, there's no real danger of engaging the starter with the engine running... as the revs are already higher than the starter. The starter won't spin fast enough to re-engage. All that's gonna happen is the starter will spin (freewheel). Let go the button and no harm, no foul.

 

[Jim]

That's a good point. I always thought it's main purpose was to help disengage the starter as soon as the motor started, and it's presence made me think it was necessary due to design (or component strength, etc)

It was first installed on the XS-2 along with the decompression system. My guess is the engineers wanted to kick the starter out while the rider was still holding the decompress lever. Let the engine chug it's way up to idle on one cylinder before the rider let go the starter/decompress lever.
Turned out that was all unnecessary.... but the safety relay was kept on more as an afterthought I'm guessin'.

 

[xjwmx]

^Could be.

 

[xjwmx]

4G why do you say AC relay? The yellow wire should be more or less steady, and a fractional part of the peak output (halved I think at first glance)

 

[Jim]

Yellow wire is from the alternator... A/C output. If you don't use an A/C relay, there's a better than even chance of relay chatter.

 

[xjwmx]

Yellow is the center of the three equally distributed phases, nothing to make it move.

 

[Jim]

Yellow is the center of the three equally distributed phases, nothing to make it move.

I'll give you a minute to think about what you just said....

 

[xjwmx]

Is the output of the generator three sine waves 120 degrees apart?

 

[gggGary]

Actually tried a DC relay, yup it chattered. The yellow wire is from a smaller 4th coil in the stator that is also tied to the common "center"
The diagrams show it as a straight wire to the center but I don't think that is the actual circuit.
The Yamaha spec above notes 4 volts as the activation threshold. It's an alternator, all the output is AC the three charging legs are rectified by diodes and lumped together into a single more or less DC output.
Fun fact: on madness at idle The LED running lights in the front tunsignals "pulse", it probably could be measured at a frequecy 3 times RPM.

 

[gggGary]

Is the output of the generator three sine waves 120 degrees apart?

To be precise and correct; It's an alternator.

 

[Jim]

Is the output of the generator three sine waves 120 degrees apart?

Yes, a star wound alternator... not a "generator." So, is it your contention that the neutral in an AC setup is DC?
I'm not really sure what your claim is.... but in a star config, the neutral will usually be about half of line to line.... and no, it doesn't magically convert itself to DC

 

[xjwmx]

^The voltage at the center connection is the sum of all voltages. Not the sum but rather the peak to peak average. If the voltages are three symmetrical sine waves evenly spaced, the center voltage should be constant, unless as 4G says, there's some trick that isn't in the diagram. I actually have to drive someone to the hospital at the moment so not going to be able to continue

 

[gggGary]

I'll stand corrected the Manual describes the yellow wire as "from the neutral point" I guess since it is at the center end of three alternating coil outputs it does kind of hoover around 0 going up and down 3 times a revolution. creating a rather fast but low voltage AC output
And yomama calls it an AC generator....

 

[gggGary]

a frequecy 3 times RPM

I guess there's another multiplier there, Jim; how many magnetic poles in the rotor?

 

[Jim]

I'll stand corrected the Manual describes the yellow wire as "from the neutral point" I guess since it is at the center end of three alternating coil outputs it does kind of hoover around 0 going up and down 3 times a revolution. creating a rather fast but low voltage AC output
And yomama calls it an AC generator....

Yep. Pardon my piss poor inking... but the neutral output would look something like this....