Dave From Maine
XS650 Member
To narrow down the problem area id have to temporarily wire in fuses of a slightly lower amperage throughout the wiring harness
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Keeps popping main fuse....
- Thread starter mrpink
- Start date
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- Tags
- electrical
And here I thought John Muir was a "tree-hugger" that co-founded the Sierra Club
75XSFLORIDA
XS650 Addict
I think it's very uncommon to have an intermittently shorted coil. If it were shorted to itself, it would not blow a 20 amp fuse, it would just charge weakly. To blow a 20 amp fuse it would take a short to ground to pull that much amperage i would think. At this time im not pointing to rotor as the issue. it could happen, but not intermittently i dont think
An intermittent short to ground would have to be a wire, something that can move around and short at times, then move a little bit physically and not short at other times.
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Actually if the rotor did shirt it would blow the 20 amp fuse. Current from the battery flows through the rotor coil , creates a magnetic field that creates the charging voltage.
If the resistance of the rotor coil drops (as it does when it shorts) high amps will flow blowing the fuse. People mess up by increasing or bypassing the fuse which then melts the wiring harness wires.
Also as noted. A bad rotor does not come and go. But knowing its current is around 2.25 amps assures it’s not the problem.
75XSFLORIDA
XS650 Addict
Yep. The math: amps = volts divided by resistance (ohms) Rotor resistance normally is 5 ohms. 12V/5ohms= 2.4 amps. But If the rotor goes bad its resistance can drop down near zero. If so, 12v/.2 ohms = ? AMPS You do the math.
75XSFLORIDA
XS650 Addict
Yep. The math: amps = volts divided by resistance (ohms) Rotor resistance normally is 5 ohms. 12V/5ohms= 2.4 amps. But If the rotor goes bad its resistance can drop down near zero. If so, 12v/.2 ohms = ? AMPS You do the math.
Yep. I get it! But like you said, rhis would not be an intermittent problem would it?? For example i rode the bike 50 miles today, over an hour bike was on nonstop and no issues. No blown fuses.
Is everyone has noted finding intermittent shorts are hard. It’s a hassle, but you could try disconnecting, or even putting fuses in line with all of the circuits that branch off of the brown wire coming out of the ignition switch.
75XSFLORIDA
XS650 Addict
Yes but what im asking is, if this rotor is shorting out would it be an INTERMITTENT issue like what i was experiencing) or maybe still am experiencing), OR would it happen ALL THE TIME??
Could be intermittent: old folks called them "fly'in shorts" as it happens on a rotor or armature than spins.....Admittedly, rare but, does happen. (I don't think that's the issue)
Mr. Ken is giving you great advice and I'm back into the peanut gallery - carry on
Hi there Skull,
On BBC for the 50th Anniversary of the Battle of Britain they interviewed a Polish Pilot. He said how he got behind a German plane and fired his guns and got the Fokker. The interviewer asked if it was a Fokker Wolf and the man replied "No it was a Messerschmitt and I got the Fokker".
On BBC for the 50th Anniversary of the Battle of Britain they interviewed a Polish Pilot. He said how he got behind a German plane and fired his guns and got the Fokker. The interviewer asked if it was a Fokker Wolf and the man replied "No it was a Messerschmitt and I got the Fokker".
Come on now it is easy to google if you dont believe what we are saying
Intermittent problems is mainly because of vibrations and / or heat .. So a Winding Coil or Alternator .can behave perfect at low temperature and then short out if hot .
fex overheat via defect regulator POFF .And when cooling down the problem does not manifest itself . You cant find it ... Impossible no one can ..
The same with a cold problem .. vibrations can shift a cable and short sometimes and not other times .depending on how it moves.
This is why a shop dont take it on .Because they fex cant find it cold -- and hot you cant touch the bike with your hands. cant do the fault finding at all.
So Dave in post # 81 has a way forward .. And there are other ways .Disconnecting most of the circuits Starter lights ..and drive with the ignition and Charging only.
Voltmeter installed but you do not appear to listen that much
That is the reason why the recommendation is to scrap cars with electrical problems and electronics it is to difficult and costly to find it.
I feel like you need to change mindset Talk less and listen more following instructions Then perhaps the experts here can get it solved maybe.
The shop that does not do it can have the bike on the yard -- but still dont take it on we have it on the internet only with unsure information much more difficult..
All the time
75XSFLORIDA
XS650 Addict
I am listening and taking the advice!!! Ken said if it was the rotor it would hapoen ALL THE TIME!! It does NOT happen all the time!! Read his last message sir. And guess what?? This isnt the only group where people know what theyre talking about. EVERY person ive spoke with says its not the rotor if its INTERMITTENT.
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In 2002, I took my XS650 on a 2,000 mile trip. 500 miles in, my main fuse blew while going down a mountain. I also had had a burp where it quit running less than 150 miles in. After changing the fuse, I continued all the way to my destination. Once on the return, I blew another main fuse. I replaced it and the bike got me home.
I parked the bike for about a month. I took it for a ride and stopped two miles from the house with a completely flat battery. Done! Dead shorted rotor. I got a rewind and it's been fine ever since. I have over 20 years since my last blown fuse. That was my experience and I toss it out there for whatever it's worth. YMMV.
I parked the bike for about a month. I took it for a ride and stopped two miles from the house with a completely flat battery. Done! Dead shorted rotor. I got a rewind and it's been fine ever since. I have over 20 years since my last blown fuse. That was my experience and I toss it out there for whatever it's worth. YMMV.
75XSFLORIDA
XS650 Addict
Remember: there are 2 different types of shorts.. Short to Ground, and Internally Shorted (shorted to itself).
It would take a short to ground to blow that 20 amp fuse. While it's technically possible to get a short to ground in the rotor, I've never seen a short to ground in a rotor and it's very unlikely to occur. If a short to ground did occur, I can't see how it could be intermittent. A short to ground in a rotor would have to be a wire rubbing through against the iron/steel frame that the coils are wound around, so the electrons flow directly from the winding to the metal frame, then to the crankshaft it's attached to, then to the crankcase.
It may be possible to happen on a bike where the rotor is connected directly to the battery, but on the XS650B, the voltage regulator feeds the voltage to the rotor, so it's not even connected to the battery. The regulator has resistors built into it that will restrict the voltage the rotor is even exposed to. The regulator controls the stator output by switching on and off the power fed to the rotor. If the rotor were to short out, I think it would damage the voltage regulator.
Later XS650s use a different wiring, with the rotor fed directly from the battery, and the regulator controls the stator output by switching on & off the ground circuit for the rotor. I can maybe see a way a short to ground in the rotor could blow a 20 amp fuse on that kind of system because if the short to ground occurs, the battery would try to discharge all of its 200 or whatever amps right through the rotor, blowing the fuse for sure. But again: 1. I have never seen that kind of short in a rotor, and 2. I don't believe that would ever be an intermittent short.
Still, because it's technically possible to happen, the tests in the manual have you test both rings to ground with your ohmmeter. The manual says that if you don't have continuity to ground with an ohmmeter, it's not shorted to ground.
Is your 75b for sale?
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