No sparks = no go

[natemoen]

Check the fuses.

Good point. Just for the sake of asking, do you still have the original glass fuses still?

[LoHo]

Still no joy. I hooked her up to a running car, 13.7V at the terminals, and still no spark untill I turned the key off, which produced an 12 gauge backfire.

When one push starts an XS, what action produces the spark? Is it battery generated or from the stator? Also, I think the headlight should come on after attempting to start the bike, but it does not.

With my booster hooked up a couple of days ago, I got sparks, but now even that doesn't make it happen. What would a bad neutral switch do to the system. Remember, the idiot lights come on and the starter cranks and turns the engine.

[petejw]

hi loho,

its the battery that produces the spark, the stator/alternator is used to keep the battery charged, if u push start the xs, u still need to have sufficient
voltage from the battery for the bike to start. (10.5 volts)

not sure about the headlight,my bike has an on/off switch.

with regards to the neutral light, is the light coming on when its in neutral?
if not that would prevent the engine from turning over,
if u think the switch is suss,
disconnect the wire and earth it to the frame and see how that goes.

jat. have u checked for power at the coils when the ignition is on?

[cywelchjr]

I'm beginning to suspect that the fluctuation you saw at the TCI when cranking was just the battery voltage fluctuating. Have you tried disconnecting the tipover switch to insure that isn't the problem? Also maybe someone in your area has a known good TCI you can try? Everything here is sounding either like the pickup coil(s)/wires or the TCI. The getting spark when turning the key off says your getting voltage to the coils. Frankly and oscilloscope would be the best tool for checking this, as the voltage on the TCI side of the coils should actually be dropping to 0 momentarily for each pulse, not just wavering. The TCI throws a momentary short on the line to the coil to fire the plug, and if it's not doing a full short you will get a problem. The neutral switch will not stop the bike from either turning over with the starter or from getting spark, and I believe that if the fuses were bad you wouldn't get spark when turning the ignition off. Additionally, if the run/stop switch were not working, the bike wouldn't turn over with the starter as that is part of what that circuit does.

So, I'd start with disconnecting the tipover switch and see what happens from there, as no spark is exactly what it would cause.

[petejw]

hi cy,
my bike wont turn over unless its in neutral,
with the neutral light on,
or if in gear the clutch needs to be pulled in.
but reading loho's other post, he states the motor turns over
so it doesnt sound like the neutral switch.

[cywelchjr]

Our bikes over here don't have those interlocks, and as such can be started pretty much no matter what, at least until the 81 model year at least.

[DiverRay]

LoHo,
If you have not done it already, check ALL the grounds! Remember, electricity needs a LOOP to work, and a ground that isn't that good WILL keep it from starting. I use anti seize to keep the grounds clean. I also know from Sailors bike that a BAD battery will NOT allow the bike to fire.
Spend a little of the megabucks the State pays our teachers() and get a good battery. IF the bike has been sitting over six weeks, the Wallyworld battery is probably gone.
We need you around for the rally again, as we miss talking with you wife and son!

[SFerinTEXAS]

recently had a problem on my SF like this. My best guess that I can say fixed it was corroded connections at the TCI plug. Cant say for sure because when you mess with more than one item in a fix its hard to tell what did it. I know when I just unplugged and cleaned and replugged it was fixed. Not the first thing I did but the last. Was there every once in a while, but not up to this point after many runs since.

[SFerinTEXAS]

What I did do before this .

Swapped a known good TCI unit

Unassed the wires in the headlight bucket and jumped past the ignition switch.

Tested the p/u coils at the TCI , pulled the cover and wiggled my past repairs

Tested voltage across the unmodified fuse box. Good. Pulled fuses and jumped directly across fuses. Same

Reassembled and it fired right up.

Couple days later pulled it out and no go.

Cleaned the tci plugs and has been fine ever since. Knock on wood. Been at least 10 times it has not reoccurred since. Not certain fixed but has consistently started since

[LoHo]

Hey guys, would a starter that cranks a little too slowly result in no spark? Or could the voltage drain cause by a weak starter keep it from sparking? Are there adjustments to be made that can improve the starter's performance? New battery, cleaned connections, but still only occasional/rare sparks, besides a single spark that comes as I turn off the key. This is starting to piss me off.

[Ken Talbot]

It seems to me that the thing that is causing the starter to slow down could also be affecting your spark. When you say "cleaned connections" I assume you are confiming that you cleaned the battery connections, then I immediately wonder if that means you also cleaned the the various connections on the solenoid, the ground strap connections underneath the engine, the contacts inside the starter switch, and any wiring harness connector plug that might be associated with the starter and the ignition system. I can't help but think there must be some critical point somewhere that is still dirty or just plain loose.

I don't suppose you would be interested in throwing it on a trailer and bringing it to Revelstoke for a look-see, eh?

[LoHo]

Ken, I've cleaned every connection I can find. I'd love to drag her up the the Great White Nort', eh, but work keeps me local. I took the starter out and hooked it to the battery, and it turned okay, but not as fast as I thought it should. I know...there must be a cruddy wire or juncture somewhere that keeps the voltage down, but I can't find it. I'm thiiiiiis close to parting her out...but then I'd have to join another list and God knows how they'd treat me.

[motoman]

LoHo, not sure whether you replaced battery or confirmed it to be good. I'd start with load testing it or taking it to any battery supplier such as Interstate. Most these places have a good carbon-pile machine and load testing charts for specific battery series. That 30sec. test will either show it to be good under specified amp load for a set amount of time in seconds or condem it. Theirs no cost for the test. Putting a meter across battery and showing 12+ volts does NOT necessarily mean a cell or more won't short under load......JAT.

[LoHo]

New battery, same results.

[3Phase]

New battery, same results.

LoHo, I think you've got an ignition problem and a budding starter motor problem. How much does the voltage drop at the Red/White coil (+) wires when you run the starter motor with the bike's battery? The car/truck battery?

The '78 to '80 TCI gets full voltage and current from the large Green wire (connects to a Red/Yellow wire that runs up to the TCI) on the starter motor side of the solenoid that bypasses almost the entire electrical supply system along with the ignition ballast resistor.

While it is possible that the starter motor is burned or shorted internally, check for simple, easily repaired things like bad brushes or a worn/high mica commutator. If the commutator is bad, just get another starter motor unless you know how to re-cut the commutator and grind down the mica insulator strips.

If you used a car or truck battery (400 to 600 CCA or better?) with regular jumper cables (not speaker wire) there would be a serious smoke leak most likely followed by a shower of melted solder, copper and steel from that poor little motorcycle starter when it drew enough current to pull and hold the voltage below the 10V necessary for the TCI.

Even if all of the fuses are missing along with the start button and kill switch circuits, jumping the solenoid from the battery (+) terminal to the starter motor terminal should turn the starter motor and allow the engine to fire up and run until you remove the jumper. The starter motor will continue to run after the engine starts and the ballast resistor is bypassed so don't keep the jumper in place or starter motor will come unglued and, eventually, the TCI will burn up.

The ignition problem? I don't know, you seem to have checked everything. The single spark when you shut off the ignition shows that the TCI, for whatever reason, is not working and the coils are firing manually when you shut off the ignition switch. That really should not happen.


Check for:

Bad pickup coil connection at the TCI

Bad or broken pickup coils/wires

Bad or mis-installed tipover switch

Bad TCI.