79 GS550 No Spark Electric Conundrum

[pdqford]

Shorting the starter relay does crank the engine, but still no spark. Jumping 12vdc to the coil on the starter relay engages it and cranks the engine as well. Again no spark.

NOTE -
When the OP hot wires the starter relay, the starter relay is functional.
The starter relay can activate the starter.
The Starter motor can rotate the engine.
The engine is not locked up.
When the starter rotates the engine there is no spark produced.

The wire (yellow/white stripe) going from the ignition fuse feeds current to the kill switch
The wire coming out of the kill switch feeds current to both the starter button and the ignition coils.
Ergo: No crank.
And: No spark.

OP needs to trace out that circuit from the ignition fuse (strange that it blows) through its two connectors in the harness, to the output side of the kill switch, and identify the open, or opens, in that circuit. A wiring diagram would prolly help.

[Killer2600]

OP needs to trace out that circuit from the ignition fuse (strange that it blows) through its two connectors in the harness, to the output side of the kill switch, and identify the open, or opens, in that circuit. A wiring diagram would prolly help.

Thanks for the update of everything I missed.

The OP has wired up the kill switch to the fuse and has 12.6ish volts there. The next step would be to follow the connection from the kill switch to the coils.

A wiring diagram would indeed help but considering the GS550's only come with one fuse from the factory, the talk about fuse box and ignition fuse leads me to believe the wiring is no longer strictly factory/stock.

[BeardmanSam]

Thanks for the update of everything I missed.

The OP has wired up the kill switch to the fuse and has 12.6ish volts there. The next step would be to follow the connection from the kill switch to the coils.

A wiring diagram would indeed help but considering the GS550's only come with one fuse from the factory, the talk about fuse box and ignition fuse leads me to believe the wiring is no longer strictly factory/stock.

Bike is a GS550L, but the 'L' key on my keyboard is about shot and I'm terribad at proofreading. I have wiring diagrams (in service manual from bikecliff's site). Wiring (outside my changes and some dubious looking splices in other circuits) appears to be stock.

I did run new wire to the coils as well. I'm leaning toward connectors being the culprit as when I ran new wire I had to splice into some of the existing connectors. I'll be picking up a nice big box of spade connectors and more wire today and will try getting rid of all stock connectors. As it stands now I've still got the original connectors for the kill switch/start button and to the coils. Original wire still run to the starter relay so that'll get replaced too. New fusebox arrived yesterday so I'll also put that in and hopefully eliminate the mystery fuse blowing. With luck that'll solve my spark issue and I can get on with the other work I need/want.

And if I haven't said it enough, thanks again all for the input.

[BeardmanSam]

Longish time, no update... Life got in the way of swearing at motorcycles for a bit . After replacing the fuse box, start button/killswitch, and all associated wire the engine now cranks when the start button is depressed. I still have no spark however. Plugs are only a year old. They were pretty coated in carbon initially, but I cleaned them up early on. Will still probably replace them since spark plugs are cheap. I guess my next direction is the ignition contacts. If that looks like the issue, I'll probably just do the electronic ignition upgrade. Unfortunately that'll probably have to wait a bit.

[earlfor]

THE "continuity Light" I refer too is just a 12 volt bulb in a socket with two wires. There is no battery. It gets power from the bike.


This might help with setting the points.


Setting Points Gaps and ignition timing.

The points are located under
the round cover on the right end of the crankshaft.

The round 6" plate that both sets of points are mounted on (breaker
plate) is held in place by three screws located at 12, 4 and 8 oclock.
Loosen the 3 screws on the breaker plate. Note that the screw at 12
oclock is in a slot. Rotate the breaker plate until the 12 oclock screw
is centered in the slot. Tighten the three screws.

We will replace the left side set of points first (located at 9 oclock
position) These are the points for cylinders 1 and 4.

Take a 19 mm wrench and rotate crankshaft clcokwise until points are at widest
gap. Unscrew hold down screw on point set and remove points. Note the
white wire that goes to the point set and the placement of the insulator.
The insulator must be correct or the points will be grounded out and
will not work. Put the new points onto the breaker plate, set the gap to
14 thousandths, and lightly tighten the hold down screw. Install white wire.
Rotate crankshaft clockwise once again with 19mm wrench until points are at widest
gap. Check that widest gap remains at 14 thousandths. Adjust and
retighten holddown screw if needed.

Rotate crankshaft clockwise until rightside points are at widest gap (for
cylinders 2 and 3) Remove old points and install new points and set gap
at 14 thousandths. Note insulators on black wire installation. Rotate
crankshaft clockwise with 19 mm wrench again stopping at widest gap. Recheck gap
as you did with the left pointset. Adjust and retighten hold down screw
on points if needed.

THE ABOVE COVERS SETTING THE POINTS GAPS




Next is the timing:

Timing for cylinders 1 and 4 (the left set of points)....................
With 19 mm wrench, rotate crankshaft clockwise while looking through the timing
window and align the mark that looks like F1| with the timing mark on
the engine case.
(the line following F1 is the mark (|)

note: some bikes will have a stationary timing mark on the engine case
and some will have a mark on a stationary timing plate that can be seen
through the timing window) If you see no timing mark on the case, and the timing plate
is missing, the location of the case timing mark is the left edge of
the 12 o'clock screw head.

Connect a continuity lights wire lead/clip to the white wire clip on the
left pointset. Clamp continuity light probe tip to ground on the bike or
battery negative terminal.

Turn ignition switch to on (do not attempt to start bike, just switch
ignition to on)

The continuity light should be on.

Loosen the three screws on the breaker plate located at 12, 4 and 8
oclock. Rotate breaker plate until continuity light just flickers out.
Retighten the 12, 4, and 8 oclock screws on the breaker plate.

Unclip continuity lead from left pointset.



For the Right pointset
Rotate crankshaft clockwise with wrench until you see the timing mark F2| become
aligned with the stationary timing mark on the engine case.
Connect continuity light lead to black wire on right pointset.
The ignition should be switched on and the continuity light should be on.

The right pointset is mounted to a breaker half plate.
You will see that you can loosen the mounting screws on this breaker
half plate and this will allow you to move the right pointset. This will
adjust the timing without changing the points gap. When you rotated the
complete breaker plate for the left pointset to get the continuity light
to flicker out, thats what you did. You adjusted the timing on cylinders
1 and 4 without changing the gap on their pointset.
Unfortunately, the whole breaker plate being rotated moves BOTH sets of
points, so that is why you must set the left side first and that is why
the right side is mounted on its own independent half breaker plate.
SOoooooo.... Smile Loosen the breaker half plate on the right side and
rotate as needed to cause the continuity light to just flicker out.
Tighten the half plate back down when satisfied with the adjustment. Smile

Remove continuity light and HOPEFULLY, start bike..

[Killer2600]

Connect a continuity lights wire lead/clip to the white wire clip on the
left pointset. Clamp continuity light probe tip to ground on the bike or
battery negative terminal.

Turn ignition switch to on (do not attempt to start bike, just switch
ignition to on)

The continuity light should be on.

You wouldn't use a continuity light in this fashion. I believe you are thinking of a "Test Light". A continuity light could be use for this but the points would have to be disconnected from the coils and the continuity light/tester connected between the point breaker and ground - the continuity light would illuminate when the points were closed.

[earlfor]

You wouldn't use a continuity light in this fashion. I believe you are thinking of a "Test Light". A continuity light could be use for this but the points would have to be disconnected from the coils and the continuity light/tester connected between the point breaker and ground - the continuity light would illuminate when the points were closed.

I've been doing exactly as I said for 21 years. It is correct. I said continuity light, I was referring to using a bulb to show continuity. Perhaps I should have said continuity bulb.

A continuity tester has a self contained battery and would be used with the ignition off. a continuity light/bulb is only two wires, no battery and used with the ignition on.

[Killer2600]

I've been doing exactly as I said for 21 years. It is correct. I said continuity light, I was referring to using a bulb to show continuity. Perhaps I should have said continuity bulb.

A continuity tester has a self contained battery and would be used with the ignition off. a continuity light/bulb is only two wires, no battery and used with the ignition on.

Did you read what you wrote? Does it sound right to you?

Continuity light/bulb/tester/setting-on-multi-meter is self-powered/contained. A circuit tester aka test light is the one that requires external power. Two tools that can look exactly the same but do two completely different things.

[BeardmanSam]

This might help with setting the points.

Setting Points Gaps and ignition timing.

Remove continuity light and HOPEFULLY, start bike..

Incredibly helpful as I've never done any of this. Thank you. I haven't had time to work on the bike recently, and when I have had the time weather hasn't cooperated . Hopefully I'll be able to get out there this weekend. I'll make sure to update once I do.

[earlfor]

Incredibly helpful as I've never done any of this. Thank you. I haven't had time to work on the bike recently, and when I have had the time weather hasn't cooperated . Hopefully I'll be able to get out there this weekend. I'll make sure to update once I do.

With any luck, it'll get you running. Good luck!

[BeardmanSam]

Been a hot minute, but I thought I'd update. Between changing jobs and a promotion at the new job I hadn't had a lot of time to work on motorcycles. I now have spark (and crank). To date:

• Replaced the fusebox (and upgraded to blade fuses).
• Points were about shot, upgraded to a Dyna S ignition (also swapped to dyna coils because job change came with a raise).
• New start button/kill switch.
• New wire and connectors throughout the ignition circuit.

Unfortunately, due to new job and new new job I didn't have much of any time to work on bikes. In the meantime, I've stopped getting fuel through the petcock. Guess that's what I get for letting it sit for a year. Cest la vie, at least it's an easy fix.