Sudden Flame Out

Flatspot · Aug 24, 2021

I forgot to mention that prior to fitting the new switch and also a voltmeter, I noticed my ignition warning light was flashing intermittently at highish RPMs. When I went to fit the new switch I’m not convinced that all of the Lucars were firmly seated. I lightly crimped these in order to force them onto the contacts.

Yesterday I went out for a fast ride for the first time since I fitted the new switch. All was now AOK and working exactly as it should.

The voltmeter was initially at 13.2v at rest (Shorai Lithium battery) and then at a moderate speed was 13.5v. Wind it on a bit more

and it would go 13.9/14.0v

right now, just checked, it is showing 13.4v

baz · Aug 24, 2021

Fast Eddie said:
Question for the clever ones at the front of the class…

When something like this happens (sudden intermittent power loss) does the power cause a spike when it comes back in?

And does / can this sudden loss / spike harm things?

What I‘m really wondering here is could this kind of fault be a reason why some folks see components fail whilst others enjoy long reliable service (like Tri Spark for example) ??

You can fit a 12v inverter to your ignition to ensure you have a smooth 12v supply whatever your regulator is doing

MexicoMike · Aug 24, 2021

The problem described in the OP is an electrical issue, not a fueling issue.

FWIW, the old saying originally is "Ninety percent of all carburetor problems are electrical." PERIOD. It is an old saying because it is correct. Other than running out of fuel, carbs almost never cause an engine to quit running while riding down the road but electrical issues do.

acadian · Aug 24, 2021

Battery terminals loose? Mine vibrated loose so frequently that I switched to lock nuts.

Check the easy stuff first, maybe bypass the kill switch as already noted.

Tornado · Aug 24, 2021

acadian said:
Battery terminals loose? Mine vibrated loose so frequently that I switched to lock nuts.

Check the easy stuff first, maybe bypass the kill switch as already noted.

Batt termins seemed tight, unable to move by fingers. Only connection that I did find could be moved by finger pokes was one coil terminal. Not loose enough to move freely, just able to swivel the ring terminal with medium force, so should not be breaking contact. Will snug it anyway.

I guess the bad thing about this sort of issue, its not consistent enough to know you've resolved with certainty. As I tried to describe, three shut downs happened in middle of multi hour ride. First hour and half, all fine, up/down a local mountain and around town. Then a good 10-15 min at 50 mph steady, fine until a few power hiccups made me want to pull off, where first shutdown happened as I pulled away from a stop sign. Two more shutdown happened along side streets within no more than ten minutes of each other. After last one, she ran another ten minutes fine until I reached my destination for a rest up. Went fine entire ride home, all on side roads, at least an hour and a half. All i'd done after shut downs was wiggle connections about looking for obvious problems.

oldmikew · Aug 24, 2021

Check your fuse holder especially if original with glass fuse

Tornado · Aug 24, 2021

OK, went through the big rubber Lucar and smaller nearby ones. Found one bullet not firmly held but it is only for indicator circuit. Gave the female side a bit of crimping and now it is firm. Moved the negative lead off the SparkBright from the ign switch white lead direct to batt -ve post. She comes on as a steady amber, indicating not charging but still over 12v warning. Should sit like this for weeks if batt is good and decent charged according to SparkBright's web page. Interesting this is not what I have while riding or with engine off with previous connections...would always move to other lower voltage warnings....so this likely indicates some resistance in the wiring harness.

Took the EMGO ign switch off and swapped back in the Lucas switch that came on the bike. I'd worked on it to clean up all the internal contacts and seems consistent...but not fussed to change it out in future.
Snugged up all the coil ring terminal nuts...only the one needed more than 1/8 turn.
Poked a wire into the tank vent and spun it about...no sign of detritus....gave it a blast with carb cleaner for good measure.

No sign of fuel in see through filters being discoloured.

Test ride to come...

Tornado · Aug 24, 2021

oldmikew said:
Check your fuse holder especially if original with glass fuse

I have a modern mini fuse holder in place of original glass type. It has an LED open circuit warning lamp...visible from behind left side cover. Connections seem good.

Beemer · Aug 24, 2021

When it died did you pop the gas cap or not?

Tornado · Aug 24, 2021

Beemer said:
When it died did you pop the gas cap or not?

Might have done so on one of shutdowns to confirm fuel level. But this was in concert with wire checks, wiggling so not determinative. And it went all the way home just fine for over 1 hr without opening cap, so vent would of had to self clear if that was cause.

MexicoMike · Aug 25, 2021

Coils can do decidedly weird things but if you have the OEM-style dual coils, it's hardly possible that both coils cut out at the same time unless their power is cut. Same is true of the rest of the secondary - plugs and plug wires. SO it seems to me it has to be some part of the common primary ignition wiring, including the EI, itself. Also, have you verified a good ground to the engine/EI?

As noted, the OEM Lucas kill switch could be causing a problem - easy enough to check by bypassing. I know lots of folks permanently bypass it. Mine is in the circuit and I've never had any difficulty with it. I cleaned/lubed it some years ago when I installed the Alton Estart, using the OEM spare button for the starter. I wouldn't have any trouble with bypassing it since I never actually use it anyway but I have a pet peeve that demands that components work the way they are supposed to work! Admittedly, this can cause a lot of time/effort to "fix" something that doesn't really matter!

maylar · Aug 25, 2021

MexicoMike said:
Coils can do decidedly weird things but if you have the OEM-style dual coils, it's hardly possible that both coils cut out at the same time unless their power is cut.

With wasted spark ignition the coils are in series. If either coil fails it'll affect both sides.

kommando · Aug 25, 2021

The engine is rubber mounted, the earth connection is well away from the head and if you are not running a dual coil then a good earth path is needed for the spark at the plugs as its wasted spark for EI so more current. My earth path got compromised inside the harness, most likely got down to a couple of strands. Lost spark on one side, the cure was to run a dedicated earth wire from head steady bolt to battery terminal, never bothered to find the fault in the harness, it died completely 2 years later and was replaced.

baz · Aug 25, 2021

maylar said:
With wasted spark ignition the coils are in series. If either coil fails it'll affect both sides.

That's not always the case
My coils are wired in series and when the left one was failing it was cutting out on the right hand cylinder
It took me a while to realize what was happening
The left coil was still giving a good spark, still running but no power coming back out to feed the right coil
Intermittent at first then eventually it cut completely on the right

Tornado · Aug 27, 2021

So I've just come back from first test ride after checking connections/swapping the original lucas ign switch back in, re-wiring SparkBright LED directly to battery terminals. No sign of the flame out on mostly around town riding, over 1.5 hrs. Not conclusive but hopeful. The SparkBright is showing much more consistant readings now. Stays amber while shut down for at least several days (no way to turn it off) and keeps amber until about 1800-2000 rpm, then goes green, staying solid throughout the ride 'cept at longer signal light stops (as it should).

New issue suddenly appeared....my left side turn signals no longer flash, including the turn warning lamp. Works fine on right side. While checking things today I was gob-smacked to see hte brake lamp blinking only when non-functioning left turn signals switch on! Somehow somethings become shorted or cross connected. I did a preliminary light check two days ago after installing ign switch etc...no problem on left flashers (but I didn't look to see if brake was blinking then!).

These are still original (?) incandescent in the turn lamps, LED in the tail/stop lamp. I presume losing one flash bulb does not prevent other same side bulb from working or warning flasher, correct? So unlikely a failed single bulb...likewise unlikely two at same time. So perhaps switch gear anomaly, a loose/shorted bullet in the undertank block or something in the tail lamp housing connectors.
Other places to check?

baz · Aug 27, 2021

Tornado said:
So I've just come back from first test ride after checking connections/swapping the original lucas ign switch back in, re-wiring SparkBright LED directly to battery terminals. No sign of the flame out on mostly around town riding, over 1.5 hrs. Not conclusive but hopeful. The SparkBright is showing much more consistant readings now. Stays amber while shut down for at least several days (no way to turn it off) and keeps amber until about 1800-2000 rpm, then goes green, staying solid throughout the ride 'cept at longer signal light stops (as it should).

New issue suddenly appeared....my left side turn signals no longer flash, including the turn warning lamp. Works fine on right side. While checking things today I was gob-smacked to see hte brake lamp blinking only when non-functioning left turn signals switch on! Somehow somethings become shorted or cross connected. I did a preliminary light check two days ago after installing ign switch etc...no problem on left flashers (but I didn't look to see if brake was blinking then!).

These are still original (?) incandescent in the turn lamps, LED in the tail/stop lamp. I presume losing one flash bulb does not prevent other same side bulb from working or warning flasher, correct? So unlikely a failed single bulb...likewise unlikely two at same time. So perhaps switch gear anomaly, a loose/shorted bullet in the undertank block or something in the tail lamp housing connectors.
Other places to check?

Never seen the tail light flash instead of the indicators before!
I have seen a tail light come on with the indicators on a car
On a car this is usually an earth problem

ashman · Aug 27, 2021

Yes could be a earth problem, I no longer when doing rewiring jobs I don't run the earth wire with the rest of the wiring, keep it seperate to the rest of the wiring, my old Triumph got a short and melted the whole earth wire in the wiring harnest what a mess so after that happen my earth wire don't get rapped up with the power wire in fact the earth wire don't get wrapped up at all.

RoadScholar · Aug 27, 2021

Sounds like it needs an exorcism...

If the appliances are wired correctly, sounds like they are, then you have a cross power path.

When one directional bulb fails the remaining bulb blinks faster, when a directional circuit is feeding another circuit the blinker relay see too much resistance and stops blinking. You can test this by removing the taillight bulb.

Best.

Tornado · Aug 27, 2021

Looking over the schematic for the bike '74 850, I see the brown line is what powers the stop light (which is what is blinking in this case). So any power getting to the brown must happen after the front/rear brake light switches (which should be open when I tested using flasher switch to the left).The brake and tail lamp is an LED array board from Dynamo Regulator Conversions (www.dynamoregulatorconversions.com/) ...so doesn't need much to trigger I guess.
Time for some sleuthing....

When I was checking the bullet block connector a few days back, I did find one lose fitting bullet...the GreenRed....which turns out to be the left side indicator line. Coinky-dinky? I pulled it out, gave the bullet female side a light squeeze and replaced the G/R...much firmer grab. Maybe I disturbed the opposite side or accidentally put back GR in the wrong location. That's what I'll check first...but alas the tank has to come off yet again...

Reggie · Aug 28, 2021

Tornado said:
New issue suddenly appeared....my left side turn signals no longer flash, including the turn warning lamp. Works fine on right side. While checking things today I was gob-smacked to see hte brake lamp blinking only when non-functioning left turn signals switch on!

As suggested by Baz and Ashman, the most likely culprit is a poor earth.
Easy way to check. Take the indicator lens off. Get some wire and take some insulator off from both ends. Place one end of the wire on the indicator light fitting next to where the screw attaches the bulb fitting to the indicator casing, and the other on the battery earth terminal, and turn the L.H. indicator on and see if it is now working.
Do this one at a time front and rear. If the indicator starts to work normally, you need to run an earth or get an earth connection from the affected indicator.

Sudden Flame Out

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