Topic: Bizarre behaviour

[Trevor from Warragul]

Coming home on my 350/4 I noticed the indicators were a bit slow & dull.  I pulled into the driveway, left the motor on, and checked out the headlight & taillight.  Both were also dull.  Hmmm.  I turned off the ignition and the motor cut out, but the starter began turning over full pelt!  I tried the kill switch, but it made no difference.  I turned the ignition on, & the motor fired up, then I turned it off & the starter went off again, eventually draining the battery.  I took out the battery & hooked up another.  The starter tried to kick over & I immediately took off the + battery lead.  I reconnected & this time there was no starter.  I thought "Geeze, I've killed the bike", then I looked at the dash.  The oil & neutral light were on!  I hit the starter button & she fired up.  I turned off the ignition & she switched off like normal.  I turned her on again & there was no crazy starter.  I hit the button & she fired up.  So it appears she's back to normal.  I've had this bike for 10 years & it's NEVER done this.

Any thoughts?  Suggestions?  Possible exorcism required?

Trevor

[Bob Wessner]

That is strange behavior. You didn't happen to stumble into the Twilight Zone did you? 

On a more serious note, I have no idea, never heard anything similar before.

[Raul CB750K1]

In my opinion, you have had a stuck starter motor relay. Generally it's near the battery. Track the starter motor wire; it bolts to the relay in the opposite end. You will probably have to open it, and clean, sand and file the copper contacts.


Raul

[Bob Wessner]

Raul,

Your suggestion does make sense after rereading it.

Trevor,

Let us know what the fix was when you find the culprit.

[Raul CB750K1]

Your starter motor could be toast now, at least the brushes. If fixing the starter relay solves the problem, run the hell out of it until the starter gives up, then remove it and fix it. If it ain't broke, don't fix it.


Raul

[apormarkos]

i'm with raul on this one.  waaay back when i got my first bike, a '74 cb360, i made the mistake of jumping it with a car, and since the bike was in a very poor state of tune, i did it often... and for more than 10 secs at a time.  anyway, it happened one time that the starter relay kinda got burned shut, and the starter would engage any time the ignition was on.  sounds like you might have to replace it.
apor

[Steve F]

I had a "stuck" starter on my red 750F a couple of times.  Turned out the starter button was the culprit.  Now, almost every time after I start it I check to see if the headlight is on which is an indication that the starter button isn't stuck in the "start" position.  Not sure about the 350's but on my 750's, the headlight is on all the time unless you're cranking with the starter button since the headlight also goes through the button.  BTW, I was riding the bike for a couple of miles when that happened, and didn't notice anything wrong until I stopped at a light and discovered it.  The starter motor is fine to this day.

[Raul CB750K1]

That's a good point. It could also be an stuck starter switch. The best way to check it is to remove the energizing wire in the relay -I believe it's the yellow-orange wire, can' remember wether the relay was actuated by giving juice or earthing through the starter button. With this connector open, the relay could not be energized. If the starter motor still runs as soon as the ignition is switched on, then the fault is in the relay. As you don't have the trouble anymore, that could have been the reason.

A high current during a prolonged time can lead to the copper inside the relay to melt and stuck closed, but there are not many chances of it releasing by itself. Stuck starter button means much more sense to me now.


Raul