Keeps popping main fuse....

[kenintn]

Hey Ken,

Could badly worn brushes cause this???

If you're asking if brushes could cause the fuse to blow... that would be a No. Worn brushes would tend to cause the charging voltage to fall off and at some point you'd find your battery was low due to drain.

If you're asking could worn brushes cause the rotor to go bad, again that would be a NO. About the only thing worn brushes could do is create arching on the slip rings from poor connection and destroy them.

FWIW: I know from experience trying to find intermittent problems like this is frustrating, but hang in there. You'll figure it out.

ken

 

[EvenmoreXS]

Great. Thanks. It does help alot to weed out the things that its NOT. Keeps me from wasting time and money. I have it narrowed down to the rotor, or still some ghost short somewhere along one wire. Ive traced everything and tried to force it to happen but cant get it to blow on my own. Leads me to believe it could be the rotor. I will check the amperage tonight and post the results.

How about a short in my switches on my bars? Horn button missing, and starter button presses but nada happens.

 

[kenintn]

How about a short in my switches on my bars? Horn button missing, and starter button presses but nada happens.

The horn button just grounds the wire to the h-bar to make the horn blow so this would not cause the fuse problem.

Same applies to the starter button. Not knowing the history of your bike one can only guess why the start button doesn't work. Do you hear a click when you press the starter button? Note that the '81 models have a neutral and clutch relay so the bike won't start unless the bike is in neutral and or the clutch handle is pulled in. If these circuits switches aren't working or have been removed the bike won't start.

The L/W wire runs from the starter solenoid to the h-bar switch. If you have removed several relays you only need to connect the R/W wire on the starter solenoid to a switched fused circuit. Then the starter should work. (BE SHURE BIKE IS IN NEUTRAL!! )

Also,... note that there is a grounding strap that connects the h-bar to the frame under the h-bars on one of the two bolts that mount the h-bars in the large rubber dampers. If this has been removed or broken there would be no ground and again the starter would not work.

Ken
.

 

[XSLeo]

The ground path from the bars to the battery can go two ways, The early bikes , like my 75 have the ground wire from a riser bolt around to an upper tree clamp bolt. This grounds the horn and stsart button through the neck bearings to the frame then back to the battery. On the later models they ground path was on a wire from the left side swiych housing down into the headlight bucket to the harness ground there. So the horn grounded through the wire, the vstart button used the bars over to the left switch then along the black wire.
Either way works, but grounding through the neck bearings is not the vest way. It can cause extra wear, pitting and corrosion on the bearings and races.
If you have an early bike with the ground wire from riser to tree just move the wire from the tree and extand it to reach back under the tank and hook it under a coil mount bolt. This will bypass the neck bearings.
In your pics the heavy cable isn't the problem, the samller red wire, if that gets squeezed between the cover it's mount, then that can short out. But wouldn't blow a fuse. Thats the main power wire from the battery to the fuse.
If it was anything touching the cover you would find the traces of arcing to the cover some where.
Leo

 

[EvenmoreXS]

Well, its been a few days, obviously. Whatever I did, not exactly sure...sigh....worked. No issues since. Knocked on wood. No more blown fuses after electrical .......straightening up.....for lack of a better term. Haven't checked the brushes yet, will very soon, but so far so good. I wish id found a smoking gun, but I couldn't replicate the issue no matter what I tried. But now it ain't broke, gonna leave it alone for now and move on. 2 weeks with no problems, .....thanks everyone for the help. There are still several things in this thread I will do soon. Now, on to the case of the disappearing oil .......ohhhhh ahhhhhhh. But that's another thread.

 

[frankmackie]

thanks for this... been looking up how to remove the saftey relay and the reserve lighting unit and this thread helped. thanks

 

[EvenmoreXS]

thanks for this... been looking up how to remove the saftey relay and the reserve lighting unit and this thread helped. thanks

Glad I could help. Bikes been running great until today. Got to work and someone came and got me becuase my gas was leaking out from my right carb. AWESOME!

 

[EvenmoreXS]

UPDATE:

Rebuilt my carbs last weekend. NO more leaks and is running great. Adjusted my butterflies and idle, new gaskets and checked for a vacuum leak,,,,,negative.....So far so good since carb rebuild. Next:.....Sump filter, then cam chain guide.

 

[75XSFLORIDA]

From what you noted you most likely have what's called a threshold current failure of the main fuse. SAY WHAT???
Fuses are designed to blow at a certain current within a certain time. The time required to blow the fuse once it reaches its failure rating is inversely proportional to the current the fuse is seeing. Simply stated, the more current the fuse see past it rated value the quicker it will blow. A 20 amp fuse will actually not blow as soon as the current reaches 20 amps. It might last 1 or 2 minutes depending on things like the ambient temp and such.. But kick the current up to say 30 amps and it will blow fairly quick.. ( To those that know fuses don't misconstrue this info with a time delay fuse since they are rated to fail at a much higher percent over current rate.)

Back to the threshold current statement.. Your fuse is could be seeing current hovering just below or right around its failure value. You start your bike up, take off, all seems OK. But then you apply the brakes, or turn on the turn signals, this throws 3-4 amps more on the fuse and it finally melts. Or maybe just the headlight coming on puts it on the edge. (I will note that from your comments on the randomness of it blowing there could be other issues but I'd at least check this)

So how can I tell if this is happening? Simple, connect an amp meter in series with your main fuse. With the bike running the current should be below 8-9 amps or so depending on if your headlight is on/off, and such. If you're seeing upwards of 17-20 amps you've got a problem. And if you do, where is it at???

There are only 2-3 things on the 650 that can draw this kind of current and not go up in smoke. The rotor is one and it has been my experience it's the #1 culprit behind problems such as this. If it's shorted it can draw upwards of 20 amps itself. And with due respect to the slap test, a shorted rotor will still create a magnetic field even while drawing major current. Once again, it might not be the rotor but its a simple test to rule it out by measuring its current. No need to run the bike, just connect your amp meter in series with the hot brush lead and turn on the key, read the amps. It should be right around 2.25 amps. More than 3 amps and you've got rotor problems, time for a replacement

If your rotor checks good and your current looks normal look at the grommets going through the headlight can and see it they've cut through and if any wires have rubbed through and are touching the can. Note there are some more checks you can do if the above doesn't uncover your problem.

Good luck and lets us know what you find. Inquiring minds want to know.

Ken


http://tinyurl.com/45ywb6a

Hey Ken, old thread. Dont know if youre stillaround. But you said touch meter probe to hot brush and other to any ground correct and should be no more then 2.25amps??

 

[GLJ]

Hey Ken, old thread. Dont know if youre stillaround. But you said touch meter probe to hot brush and other to any ground correct and should be no more then 2.25amps??

@75XSFLORIDA double check that you have the brush screws in the right holes. Just came up the other day where a member was blowing the main fuse because he mixed up a couple of the brush screws.

 

[75XSFLORIDA]

@75XSFLORIDA double check that you have the brush screws in the right holes. Just came up the other day where a member was blowing the main fuse because he mixed up a couple of the brush screws.

Yes, I read that. I literally just double checked and my screws are all fine… been thru this whole bike and I keep blowing 20A fuses but intermittently. Everything in the headlight bucket is fine, the grommets are fine. No issues there. I’ve gone through every connector everywhere and nothing is shorting out but I still keep blowing these fuses. Rotor tests out fine….

 

[Jim]

But you said touch meter probe to hot brush and other to any ground correct (?)

No that's not correct. He said to hook the meter in series with the hot brush.

 

[75XSFLORIDA]

@75XSFLORIDA double check that you have the brush screws in the right holes. Just came up the other day where a member was blowing the main fuse because he mixed up a couple of the brush screws.

Do you know how to do the hot brush lead test to ground though that I was referring to or asking about? Slipring tests ohm out fine.

 

[75XSFLORIDA]

No that's not correct. He said to hook the meter in series with the hot brush.

Ok got ya! Not sure how to do that, but I’ll figure it out. Thanks.

 

[magoo66]

Ok got ya! Not sure how to do that, but I’ll figure it out. Thanks.

Has your tail light blown any time when rear brake is a applied and fuse blown?

 

[75XSFLORIDA]

Has your tail light blown any time when rear brake is a applied and fuse blown?

Nope

 

[GLJ]

@75XSFLORIDA
Ok let's start from the beginning. Does your fuse blow as soon as you turn the key on?

 

[75XSFLORIDA]

@75XSFLORIDA
Ok let's start from the beginning. Does your fuse blow as soon as you turn the key on?

No sir….. I can ride 20 miles and nothing and then all of a sudden it blows. Put another one in and it blows within 30 seconds but not as soon as I start the bike. Idles fine. Only blows when I give it gas. But again I can ride for miles, and it will not blow. For example, I just rode for about 20 minutes with the stator disconnected and all good. I then connected stator again just to troubleshoot, and nothing blew. So again it’s very intermittent. Everything is flawless inside the headlight bucket and everywhere else. This has been an ongoing issue. no bare wires are touching anywhere.

 

[GLJ]

No sir….. I can ride 20 miles and nothing and then all of a sudden it blows. Put another one in and it blows within 30 seconds but not as soon as I start the bike. Idles fine. Only blows when I give it gas. But again I can ride for miles, and it will not blow. For example, I just rode for about 20 minutes with the stator disconnected and all good. I then connected stator again just to troubleshoot, and nothing blew. So again it’s very intermittent. Everything is flawless inside the headlight bucket and everywhere else. This has been an ongoing issue. no bare wires are touching anywhere.

Ok it sounds like your charging system may not be the problem. Intermittent shorts are the hardest things to find. Does it tend to blow when you have the brakes or tun signals on? @75XSFLORIDA

 

[75XSFLORIDA]

Ok it sounds like your charging system may not be the problem. Intermittent shorts are the hardest things to find. Does it tend to blow when you have the brakes or tun signals on? @75XSFLORIDA

Nope. Nothing to do with either of those. Blows just riding, no brakes or signals