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Blowing 20 amp main fuse
- Thread starter Shipper
- Start date
Hi again
I Notice that it appears to be a Brown and Orange wire coming out of the coil
( Orange seems to be 12 V )
on the picture , that is what I had on my 1980 -- XS 650 SE US Custom
Before Electronic Ignition was installed
But on the schematic
https://thexscafedotcom.wordpress.com/2012/01/12/xs650-75-xs-b-76-xs-c-wiring-diagram/
It appears to be Red / White + Black as stock from the Coil
Also Jim s picture seems to be the same as the schematic 1975
Point and Coil and Capacitor have a common lead.
There could be a difference here I do not believe so " The capacitor Replacement test "
will give info
And I would prefer the one that was there before since that one worked
Let us assume that it is a later coil some shop had laying around.
Who knows what is used
It can then have other specs than the 1975 Coil.
And so can the Capacitor have
It is not in theory certain that a 1975 stock coil has the same specs as a 1980 coil.
( If so why different Colors ? )
What can happen is that you buy a capacitor for a 1975 bike When in fact it is a setup from
a later bike.
Again I do not believe so but this can be something to look into later on.
Are specs for the 1975 Coil and Capacitor the same and can be changed between Year models or is there a difference.
Perhaps this is to overthink it but we have loss at high revs
And uncertainty regarding wiring.
The more info the better decisions and better running bikes.
Electric part can be sensitive if not the right corresponding parts are used.
I Notice that it appears to be a Brown and Orange wire coming out of the coil
( Orange seems to be 12 V )
on the picture , that is what I had on my 1980 -- XS 650 SE US Custom
Before Electronic Ignition was installed
But on the schematic
https://thexscafedotcom.wordpress.com/2012/01/12/xs650-75-xs-b-76-xs-c-wiring-diagram/
It appears to be Red / White + Black as stock from the Coil
Also Jim s picture seems to be the same as the schematic 1975
Point and Coil and Capacitor have a common lead.
There could be a difference here I do not believe so " The capacitor Replacement test "
will give info
And I would prefer the one that was there before since that one worked
Let us assume that it is a later coil some shop had laying around.
Who knows what is used
It can then have other specs than the 1975 Coil.
And so can the Capacitor have
It is not in theory certain that a 1975 stock coil has the same specs as a 1980 coil.
( If so why different Colors ? )
What can happen is that you buy a capacitor for a 1975 bike When in fact it is a setup from
a later bike.
Again I do not believe so but this can be something to look into later on.
Are specs for the 1975 Coil and Capacitor the same and can be changed between Year models or is there a difference.
Perhaps this is to overthink it but we have loss at high revs
And uncertainty regarding wiring.
The more info the better decisions and better running bikes.
Electric part can be sensitive if not the right corresponding parts are used.
Perhaps I have misunderstood some of the comments in this thread, but I am happy to make an ass of myself today - blue sky and 22 Celsius:
The Capacitor is composed of two capacitors tied together in a metal frame. This frame functions as the ground/earth/negative connection to the battery.
#1: These 2 wires run from the capacitors positive terminals to the harness where they connect into the points ignition system.
Wire #2 - #3: Provides a secure connection from the capacitors ground terminal to the bikes chassis via the engine mount bolts - also grounds the points and spark plugs
#4: This is the Ground Tab for the harness. If this is disconnected then various electrical items on the bike will stop working. If you look closely at the wiring diagram you will see that many electrical items use this harness ground tab. The tab also gives better connectivity for all items separated from the main chassis by the bearings in the steering head.
Edit: See 5twins post immediately below. He gives a nice tidy positioning for mounting the Harness Ground Wire Tab.
The Capacitor is composed of two capacitors tied together in a metal frame. This frame functions as the ground/earth/negative connection to the battery.
#1: These 2 wires run from the capacitors positive terminals to the harness where they connect into the points ignition system.
Wire #2 - #3: Provides a secure connection from the capacitors ground terminal to the bikes chassis via the engine mount bolts - also grounds the points and spark plugs
#4: This is the Ground Tab for the harness. If this is disconnected then various electrical items on the bike will stop working. If you look closely at the wiring diagram you will see that many electrical items use this harness ground tab. The tab also gives better connectivity for all items separated from the main chassis by the bearings in the steering head.
Edit: See 5twins post immediately below. He gives a nice tidy positioning for mounting the Harness Ground Wire Tab.
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Here's the way I've always found these grounds connected, and I believe it to be the stock configuration - the engine ground wire connects to the forward condenser mounting screw and to the top right front engine mounting bolt. The harness ground goes to one of the coil mounts .....
Notice how the open ended crimp on your harness ground wire looks spread open more. That's because it is. Someone pried it open more to fit on one of the M8 engine mount bolts. Normally it mounts to an M6 coil mount stud.
Shipper
XS650 Addict
Really helpful searching for the problem. Checked out most of the messages and confirmed ok. Did the full 'tank off' wire jiggle test and she keeps running perfect. Its only apparently under load that the fuse blows??? Still baffled. Bike ran well prior to points re and re (except for breaking down at top end), runs great idling and will run great for 5 to twenty minutes on the road (including top end) and then pop! Blown fuse. going to reassemble for another road test but really dreading what's going to happen.
Attachments
It's possible one of the coils is getting hot and shorting out. Can't really think of a good way to test fort that. 
One thing you could try is adding a 10A in-line fuse to power in, on each coil... either temporarily or permanently. If one blows you'll know it's that coil. If the 20A still blows, at least you'll know the problem is elsewhere.
One thing you could try is adding a 10A in-line fuse to power in, on each coil... either temporarily or permanently. If one blows you'll know it's that coil. If the 20A still blows, at least you'll know the problem is elsewhere.
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Shipper
XS650 Addict
In addition, once i put a new 20amp fuse in, it will start righ up and usually get me home. Might need two.
If that's the case, it points to something overheating. By the time you've got a new fuse in it, it's cooled down enough to work... 'till it overheats again.
Shipper
XS650 Addict
Are we talking replaced Capacitors with the same fault .
Are we talking inspected Points .
Connecting more fuses is an excellent Idea.
Otherwise the problem finding the fault that not manifest itself is virtually
impossible.
It happens that I have a separate wire
from fex Boyer Bransden ignition Coil that requires ground all the way to the ground on the battery
A quick check of charging Voltage with a bit higher rev is simple and quick test.
I have a Voltmeter installed when I are trying to find problems.
If Voltage is to high more heat is generated and expanding fex copper wires in alternator.
Are we talking inspected Points .
Connecting more fuses is an excellent Idea.
Otherwise the problem finding the fault that not manifest itself is virtually
impossible.
It happens that I have a separate wire
from fex Boyer Bransden ignition Coil that requires ground all the way to the ground on the battery
A quick check of charging Voltage with a bit higher rev is simple and quick test.
I have a Voltmeter installed when I are trying to find problems.
If Voltage is to high more heat is generated and expanding fex copper wires in alternator.
If not the ignition switch then I recommend you add two temporary fuses like Jim's fab suggestion.
Shipper
XS650 Addict
Agreed. That’s definitely plan B. But after jerry rigging the switch, no blown fuse on the test run. Fingers crossed but the switch was real sloppy. If that don’t work, Jim’s plan is in effect.
Thanks
Thanks
The coil has about 4Ω resistance. Since the points and condenser are downstream of the coil, overall resistance wouldn't change if they shorted out. Besides, the points spend half their life going straight to ground anyway....
I Se what you mean. Makes sense.
But I still think an inspection is relevant since a change has been done.
there. Otherwise the situation is
Points and capacitor don't affect
Coil is the same. ( If the fuse did not burn before --why now with the same Coils )
We don't come further
The inspection can look at the cables around where the work has been done and recheck
wiring. How Capacitor and Points are connected. looking for Bare wires
If the problem is not there and around it is more difficult
I feel that the change has affected if not so
it can be anywhere. And be very difficult to find.
A bare wire fex in the taillight that only shorts at certain vibrations or so with one Fuse.
Can take many man hours to find .
A major Yamaha shop here would not take on the job.
Is the break up at high rev gone ?
Shipper
XS650 Addict
Yes, break down at high rev is gone. Test ride tonight blew no fuse. Going to spend the day tomorrow on it.
1. Ran fine with no blown fuse prior to points re and re and changed condensers.
2. Runs and starts now better than ever (including high rev),
3. Have done complete check of visible wiring with tank removed (jiggle and visible).
4. Only obvious wiring faults are with a wonky ignition switch that now will turn 360 degrees in harness and not shut off. (Battery disconnected for safety/charge concerns).
Will default to Jim’s 10 amp fuse strategy if tomorrow brings no relief.
Thanks crew
Steve C
XS650 Addict
Only way to blow a fuse is to short battery + to ground. Points ground and unground the coils. If they ground out all the time you lose spark but would not blow a fuse. Sounds like your key switch is grounding power (batt +) internally. Hopefully you found the gremlin!
Did you find an obvious place where a short circuit was occurring in the ignition switch?
Shipper
XS650 Addict
This is unbelievable! How many of you have ever seen the two screws from the ignition housing shake loose and dislodge? (see pic). I don't understand the connection (if any) relative to blowing fuses as the ignition mechanism is isolated from the frame but none the less, once rectified I took the bike for a five K boot and no blown fuse. Hoping and praying that this somehow is the gremlin I been looking for as I have checked over the wiring harness and all grounds multiple times. The only thing left if the problem returns is Jim's 10 amp fuse to coil power.
Thanks for all the advice, will let you know if the problem returns. Stay well - happy riding.
Attachments
With the screws missing/loose the contacts open and close quickly. This may cause power surges that may be enough to blow the fuse.
Often a short in the tail light can blow the main fuse. It runs directly off the key switch.
I like the way the early switches had screws, easy to take apart and clean.
Leo
Often a short in the tail light can blow the main fuse. It runs directly off the key switch.
I like the way the early switches had screws, easy to take apart and clean.
Leo
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