Voltage loss?

[Nine_Iron]

I did some brief cruising of the threads and couldn't find any help. Just want to see if you guys have some advice for me.

I have a 75 XS650 mostly stock except my Pamco High Output Ignition and pod filters. My bike has been running great for a month now but recently I've been having a problem while riding. Usually at higher RPM's my bike starts to cut out and miss. Then it will die all together and won't start when I pull over. My lights and horn work but I have no spark and the starter won't even engage at all. After sitting for a few minutes I'll hit the starter button and she fires right up and I drive away only for it to do this same thing a mile or so down the road.

I thought the ignition or coil was breaking down but when it dies my starter won't even engage. So I'm assuming voltage regulator or some relay? Something heating up and shutting down , then starting after it cools? Any ideas?

Thanks guys!

 

[rpgoerlich]

If you haven't already replaced it, I'd check the fuse block and all the connections to it.

 

[retiredgentleman]

Start looking at the basics.

Prior to starting, measure battery voltage...................should be around 12.5 volts

Start engine, wait a few minutes......................voltage should be around 13.5 volts at 1200 rpm

Rev engine to 3000 rpm...................voltage should be around 14.4 volts

 

[Nine_Iron]

From what I know there is only one fuse in the main workings of this bike and it is good.

What has me stumped is after a couple minutes of riding it starts to miss, then it dies out all together. When it's dead, I have zero power to the coil and zero power to the starter but have the normal 12 volts at the lights, horn, etc. After just a few minutes of sitting I end up with full power to the coil and full power to the starter. So I start it up and drive away. Couple minutes later.....it happens all over again. Anybody else have this problem?

 

[XS650_Bobber]

Some time ago I had a similar problem, but all the electrical die in the bike, the problem was the ignition key, a bad contact inside, if your problem is not this you have to check all the connection and wires, maybe a wire is cut somewhere or a ground loose...

Try to check this and let us know...

 

[gggGary]

Eliminate the usual suspects and those are poor connections. The commonality between coil and starter button is the RH handlebar switch especially how it grounds. IIRC the early bikes don't have a ground wire from the frame to the front end and that should be added if it doesn't exist. Yamaha changed the handle bar grounds over the years which is in it's self a possible indication of problems. BOTH +12 and grounds can have issues. I would look at (remove clean check for looseness) both ends of the ground strap and the +12 from the battery to the solenoid then look to the ground wires up at the engine top mounts. Even if it doesn't fix THIS problem electrical cleaning and checking is never wasted work. And I am willing to bet chasing electrical connections will fix this. Have you checked your brushes? Once you are there it's nice to ohm out the rotor too. Most electrical work is easy, just tedious, All that stuff has had 30 years of neglect that needs a little R&R to make it happy. When you successfully arrive at your garage some dark night you will be glad you spent the time now.

 

[TwoJugs]

When you are in the no voltage to coil situation, start with the voltmeter. probe back through the system from the coils to the batt. I know it sounds simple becuase most electrical issues usually are. My favorite problems to work on. No grease, minimal tools and parts costs to fix it can somtimes be free! Sounds like a bad ground, splice or connector heating up and raising resistance. A quick jumper wire from the positive to coil can give a fast answer.