ignition loop - coil '78 XS650E

[Niels B]

Ok - what am I missing ? finished my refurbish of the '78 ( I thought ), on upstart it would not start.
After some measuring i realized the left coil was dead - no resistance on the secondary loop, consequently no spark!
replace with a working coil - this time i measure both right and left coil - got same readings both side. Check for spark - right side beautiful spark - left side no spark !
all wiring are original to the year/model, thus fairly simple. Am i overlooking something ? have good connections ! could it be the condenser in the ignition loop?
any suggestions before i give up and replace the complete ignition with electronic (which i have considered in spite of the cost)
oh if i do go electronic which do you guy thinks the best fit with the least modifications ?

 

[Jan_P]

The first thing to check is the points
Measure voltage and se if any sparking happens there.
It should also start on one cylinder or try to start

Boyer Bransden

 

[jpdevol]

If good voltage on R/W connecting to each coil, then most common would be orange wire not isolated from ground at points terminal or shorted condenser - should be no continuity to ground with points open.

 

[Niels B]

I did not measure the voltage on the R/W to the coils, I'm however sure all the isolation on the wires and the connectors are good, went through each and everyone and replaced and repaired anything suspicious prior installation. Will check the voltage from the R/W to the coils and take a closer look at the condenser - screwed up not measuring the coils before i installed them

 

[jpdevol]

So - to be clear - if you use an Ohm meter and stick one probe in the orange (or gray) connector at the coil, the other probe to a ground, and open the points' contact manually - there should be an open circuit (no continuity). There should also be continuity (0 Ohms) there when points are closed.

 

[Niels B]

got 11.8V on the R/W going to the coils - both side. tried to cross connect but still only spark on the right cylinder. also measured the voltages to the points - pretty much the same 11.8/11.7V on both. manually activating points give me a spark on the right cylinder, based on this can i assume the condenser to the left cylinder is toast ? if so assume i should replace both!

 

[Niels B]

actually just realized the condenser connection to the frame is not tight - maybe that's my issue

 

[Jan_P]

Yes Tighten the condenser and the 11.7 is a bit low It can perhaps start.
What do you have across the battery everything Off
and ignition On

 

[Bruno_c]

You can switch the condensers and see if the missing spark changes side.

 

[Niels B]

got 12.5V across the battery, tightened the screws, however no change, next switch the condenser wire and take one more look - done in the garage for the day

 

[Jan_P]

No firing at all -- not even on the Good side ???
Not Running on one cylinder ??

 

[Niels B]

It fires on the right cylinder Jan. I took the tank off to work on the coil so don’t know if it will start on one, like to get spark on both before I put it back together again

 

[Jan_P]

It will run a while on the fuel in the bowls.
OK that is progress the battery is OK
Then it is the condenser and Point.
as per JP in post #5 perhaps is a way forward.
And / Or Brunos shift the condenser
If I recall right i used to measure the upside on the point so it has the 12 V

 

[Niels B]

This is crazy ? I switched the wires on the condenser - same result - spark on the right none on the left - what am i missing? I feel like an idiot ! I've made several motorcycle electric wiring over the 50 years I have messed with motorcycles, granted this is only the 3rd XS wiring but it's basically not that different than any of the other old motorcycles i have messed with. open for any suggestion before i trash the whole ignition loop.
for good order all other electric circuits are working fine - light/brake light/turn signal/horn and all instrument lights too.

 

[jpdevol]

If the orange points wire is on your left coil, perhaps disconnect it at the connector next to coil, then turn key on and tap the orange wire to bare metal ground (make jumper if needed) - see if spark is produced at plug inserted into cap (bypasses points and condenser)

 

[Jan_P]

This is crazy ? I switched the wires on the condenser - same result - spark on the right none on the left - what am i missing? I feel like an idiot ! I've made several motorcycle electric wiring over the 50 years I have messed with motorcycles, granted this is only the 3rd XS wiring but it's basically not that different than any of the other old motorcycles i have messed with. open for any suggestion before i trash the whole ignition loop.
for good order all other electric circuits are working fine - light/brake light/turn signal/horn and all instrument lights too.

This is progress newer the less.. I shall google a wiring Schematic
Is there power in on both Coils and
Power in on both Points
Ill get back

 

[Niels B]

Don’t think it matters but for good order this is an early ‘78.
Will try suggestions. Thanks to both

 

[Jan_P]

OK
could not find any good wiring picture on Line but have one in a Clymer Book
Power to the coils come from the Kill switch so both upsides of the coils should have the same Voltage
It forks ( branches )

The downside of the coils goes to the Points ( One to the Spark Plugs )
should also have the same Voltage on the Downside not sure what value.

The downside of the coil goes towards the points and forks again one to the point and one to the condenser
And to a common ground further downstream for Point and capacitor.

So from the kill switch it is one series wire towards the Points and the Condenser
From kill switch 1 wire splits to 2 one to each upside coil and out from downside 2 wires that splits into 2 x 2
4 wires at condensers and points

You have one side sparking so measuring that side ..I would start at upside coil and then downside coil and to point and capacitor

And comparing with what you have on the non working side.

Perhaps disconnect point and capacitor and measure again - My guess is that the Point is Grounding

 

[Niels B]

OK
could not find any good wiring picture on Line but have one in a Clymer Book
Power to the coils come from the Kill switch so both upsides of the coils should have the same Voltage
It forks ( branches )

The downside of the coils goes to the Points ( One to the Spark Plugs )
should also have the same Voltage on the Downside not sure what value.

The downside of the coil goes towards the points and forks again one to the point and one to the condenser
And to a common ground further downstream for Point and capacitor.

So from the kill switch it is one series wire towards the Points and the Condenser
From kill switch 1 wire splits to 2 one to each upside coil and out from downside 2 wires that splits into 2 x 2
4 wires at condensers and points

You have one side sparking so measuring that side ..I would start at upside coil and then downside coil and to point and capacitor

And comparing with what you have on the non working side.

Perhaps disconnect point and capacitor and measure again - My guess is that the Point is Grounding

I have thought about whether the point is grounding too - I have a new set so I’ll replace the left side first and see if that makes a difference, before doing more measuring.

 

[Jan_P]

Like this
Colors can be different for your bike

Br goes to upside both Coils
Downside on coils O and One Gr
that both forks again
I believe it grounds at Point left side