Topic: 1981 Cb650C Main Fuse blowing

[Jbarth13]

Hi all,

Just installed my new stator, fired the bike up to check charging, shut if off for a minute, and found it would not start again.  Lights, everything dead with 13.18 volts in the battery.  Figured out the main 30 amp fuse on the start solenoid was blown - it would blow the instant I turned the key.  Figured out that when the 5 pin connector from stator to regulator is disconnected, the fuse doesn't blow.  Reconnected the stator to the regulator, pulled the stator off the bike, and turned the key; the fuse didn't blow.  It seems that when the brushes arent depressed, the fuse doesn't blow, but when they are pushed up against the rotor, the fuse blows.

I'm not very well educated about electronic troubleshooting. Any help is greatly appreciated.  My guess is that the brushes are somehow shorting against the stator cover.  Thoughts?

Thanks!

[goldarrow]

Trace your wires for short

[Jbarth13]

Like I said, the issue seems to involve whether the brushes are depressed. I'm wondering if anyone has any experience with this problem.  I don't think there is a short in the harness itself; it is brand new, with only one even minor pinch and no exposed wire that could ground out.

[calj737]

You may be correct about it shorting out internally, but, the wire short may be occurring beyond the plug. Never assume that's not the case. Your description certainly provides for that (wiring short) to be very possible.

You say the harness is new. New to you? A new OEM? A new re-pop? It's also possible that the harness has two wires crossed and you're getting your short due to improper wiring. Have you taken a meter to the stator while installed, but not plugged in, and tested for voltage and resistance? That's the simple way to tell instead of speculating.

[Jbarth13]

The stator harness is brand new.  The bike harness is (as far as I know) original.  Sorry for the lack of clarity there.  As I understand it calj737, you're saying the short may be in the main harness?  Which specific resistances should I check?  I as I recall resistances between the three yellows of the stator harness is .7ish ohms - right where it should be for a good stator.

[cb650]

Did u pinch the wires going to the stator?  Its been done before. 

[Jbarth13]

Possible that I pinched the wires right where they exit the cover aft of the stator cover and run up toward the regulator.  Any way I can test without cutting up the harness?

[cb650]

Run the usual stator test with a multi meter.  You should be able to look at the covering of the wires and see if it is pinched.   

[calj737]

You don't need to cut up a harness to check voltage or resistance. You can test at the plug connector.

Use this: http://www.electrosport.com/media/pdf/fault-finding-diagram.pdf to test your stator. If your harness and fuse panel are stock and original, then I'd also turn my attention to the fuse panel looking for proper voltage and exposed wires. Check it front and back with a meter.

As for checking the "pinched wires" from alternator, you might be able to verify them without removing the left side case cover, but I'm not dead certain in your bike, perhaps CB650 can confirm a method.

[Hetzel]

Could it be that the reg is bad? I had an 80 cb650c, and with the rotor went bad, it took the r/r with it. It required that both be replaced.