Rectifier Failure Symptoms

The bike in question is my 1977 Kawasaki KZ750B.

Would rectifier or Stator failure cause no spark, lights to fail and rough running? I checked all the fuses and they are good.What are they symptoms of a failing rectifier/stator and if my is no good, where can I buy one?

Thanks in advance.

Check the connectors and clean the battery minus to frame and engine connectors (Ground).
Clean all the connectors with De-oxide spray.
A bad current flow on the ground connections lead to your failure symptoms. It is not a correct closed electrical circle.

Do you have a multimeter? A diode can go bad in the rectifier/regulator, the battery could have a intermittent short, the stator could have a short or open circuit. With the meter connected you can see if there is A/C present or when the short occurs. Batteries can go bad in different ways. This is one of them.
Steve

Measure the battery voltage with the bike running and with the bike stopped. Should have a higher voltage when running.

weeZee wrote: Measure the battery voltage with the bike running and with the bike stopped. Should have a higher voltage when running.

When running its 14.4. Cant figure this out. No fuses blown but rear brake and running light wont come on, though the signals do. Its the strangest thing.

SWest wrote: Do you have a multimeter? A diode can go bad in the rectifier/regulator, the battery could have a intermittent short, the stator could have a short or open circuit. With the meter connected you can see if there is A/C present or when the short occurs. Batteries can go bad in different ways. This is one of them.
Steve

Thanks for this Steve. I assumed the battery is good because it holds a charge etc. I also am having an issue with the taillight not coming on, though i have changed the bulb so I have no idea whats going on.

Check the B/Y ground wires.
Steve

Have you done what Scirocco recommended? if you are getting 14.5 volts when bike is running, your charging system is working fine, chances are if you clean all your wire connections your bike will run better and all your lights will be brighter..

mopguy wrote: Have you done what Scirocco recommended? if you are getting 14.5 volts when bike is running, your charging system is working fine, chances are if you clean all your wire connections your bike will run better and all your lights will be brighter..

Here is the backstory:

Last week after it sat out for 10 days in below freezing temps (lead acid battery) , i put the battery back in (I had taken the battery out when it got cold and brought the battery in the house)

As I put the battery back in, the ring terminal on the battery wire from the bike, broke off. I did a quick fix, using another ring terminal and 10 gauge wire (probably a mistake since the wire to the starter is heavier gauge).

Bike tried to start but would not turn over. I think, during the process of trying to start it, I flooded the carbs. So I changed the spark plugs. It ran great for about 15 min. Hopped on the bike to take off, and it shut off. Tried to kick it. nothing. When I try to use the electric start it engages but makes this awful clacking noise if I try too long.

Fast forward to the day after:

Took off the 10 gauge quick fix wire and crimped the old wire into a ring terminal. Job done

Charged the battery on a tender last night. Its shows 13v. This morning I put it on the bike, with new spark plugs, and after a few kicks it started right up.

I checked the voltage at the battery while the bike was running and it was 14.4v

Issues:
I noticed the neutral light no longer comes on, but thats ok.
The brake light no longer comes on.
The running light does, but not the brake light, though I changed the bulb.

Went for a ride and stopped for a minute. Started up OK but the starter made that weird AWFUL "trying" noise again.

Got back home, and with the bike idling, turned on the headlight. The bike died immediately.

Sounds like a weak battery, possibly with a bad connection between the -VE terminal and the engine ground point.

weeZee wrote: Sounds like a weak battery, possibly with a bad connection between the -VE terminal and the engine ground point.

Battery was put on a tender and fully charged. Reads 14.4v when the bike is running.

An old battery can hold a charge, but still not be able to crank a starter effectively.
If you get a chance, try the starter with a fresh battery to check.