Another ignition issue

I'm having this issue with my Ranger, but am posting on the the Commando forum because its the same ignition system.

I restored the Ranger in 2010-2011, using the original wiring harness. I replaced the blue can and rectifier, used the 6V coils that came with the bike, and put a used Boyer MkIV on it. I put a kill switch on it from a later Triumph that broke the continuity of the ignition (white) wire rather than ground it, and everything worked well until a few months ago. Bike has traveled a little over 4000 miles since its rebirth.

Mid-summer, I was out riding, and had gone about 50 miles when the bike suddenly died. I had no tools with me, as the bike had had no issues. I managed to unscrew the side cover with a coin, and found one of the leads going to the kill switch had come apart - its one of those Lucas things where you have to connect a pair of female spade connectors with a double-male insert. I re-connected the leads, bike started right up, and I thought nothing of it. It happened again a month later, and I removed the kill switch from the circuit.

Fast-forward a few months to Barber. I took the Ranger there, and planned to use it as my ride-around bike. I put about 100 miles on it Thursday with no issues. On Friday, the bike died just as I was going through the gate near the swap meet area. I pushed and coasted into the AJS/Matchless Club in the swap area, opened the cover, checked connections, found nothing wrong, but the bike started right up. Figured a connection must have vibrated loose, and my checking things made good contact again. The next morning, about 30 miles later, the bike died again, and that was the end of my riding it at Barber. I checked all connections, and everything worked except spark. Assuming the Boyer box was bad, I picked one up at the swap meet.

With the bike back home, I replaced the Boyer box, pick up plate, and wires from the distributor to the Boyer. Bike started right up and seemed cured. Out on its first extended ride since this happened, the bike died again - no spark, but lights and horn. I found the white harness connector to the Boyer seemed to have an intermittent short, and decided it was time to replace the harness.

Got a new harness from British Wiring, and replaced the old one, checking all the connections before buttoning things up. I did find a break in the white wire in the harness, and felt justified in my decision to replace it.With the plugs out and grounding on the head bolts, I kicked the bike several times without the battery, and got a nice, strong spark. Connected everything, and bike started right up. Rode the bike around the neighborhood 3 or 4 times, and about a half mile from home after 15 minutes of riding, it died again. No spark, but lights, brake light and horn. Walked the bike home, parked it in the garage, and had a beer.

Went back in the garage this evening, checking connections with a volt-ohm meter. No breaks in any wires, all connections are solid. Ignition switch is the Lucas 2-position switch, and seems to work fine - lighting wire (brown/white) shares the same terminal on the switch as the ignition wire (white), so if the switch was bad, I wouldn't have lights either. Checked resistance on coils - left one reads 1.8 ohms, right reads 2.0.

Kicked the bike again with plugs out and grounded, and battery out of circuit - spark.

Is it possible one or both of the coils is bad, and shorts out when hot or exposed to more than 13 volts? If one coil shorts out, could it cause total loss of spark since they're connected in series?

My brain is fried.

I think I'm replacing these coils anyway, but would like to know it there's a definitive test for my own peace of mind.

Probably fuel related then? That's how it works in my life anyway.

Snorton74 said:

Probably fuel related then? That's how it works in my life anyway.

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That was kinda my thinking as well.

A coil with low resistance due to a shorted winding could cause the ignition to shut down. I would call that a long shot - but possible.

First I would be watching the battery voltage. High or low battery voltage can cause it to shut down. Jim

Two things linger on my P!! with points where carbs leak on, one the acceleration and two the Vibration. To test the Boyer power supply ya turn on with battery and plugs on head then flick tug jerk and bang around till a spark snaps, then try to figure out what your action actually affected and dig in. The coils I've had short out were intermittent at first mystery then nothing show stopper - till i tape wrapped insulated the bad one and semi wired on frame to get home on both jugs. Boyer shares them so if one coil goes no spark on both sides. The boyah trigger wires are also infamous breaking inside insulation for intermittent spark to run and stop but checks ok at rest, unless ya flick at em with key on or test conduction twisting tugging flicking, or just assume they are bad, as sure will be too soon and replace with Greg Fault's kit or DIY better terminals and RTV back up.
i assume you only have one fuse, so if lights works so does fuse but I've had glass kind look fine but not conduct, in case that catches ya out no power no where.

I havent noticed where you have put new spark plugs in ??????? Even if there new, change them..... The most obvious is usually the most overlooked........

Also is your fuel tank "breathing" are you getting a "vapour/vacumn lock".. Have you recently changed the tank cap ???

Fuel is not an issue. It's lack of spark.
Plugs, wiring harness, Boyer box, pick up plate, rotor, distributor wires, coil wires, plug wires are all new. Ignition switch is not new, but is the 2-position version and checks out fine (I wouldn't have lights if the switch was bad).

Zener diode is original, but seems to work OK. Battery has a full charge ~12.7 volts and goes up to about 14.6 volts when revved up. The stator is an Emgo 16A version, same as what I have on the Commando and G15. Rectifier is relatively new, bought during the rebuild. Its the only new one I've got - the other bikes have the originals, and I have a spare original.

At first I thought it was the Boyer, because it was a used item off ebay, and I've heard of the box or pick up plate going bad. Didn't solve it.

Then I thought it was the wiring harness, which is 45 years old, and finding the break in the white wire seemed to confirm it. It could be that all my fiddling with the connections over the past few months caused the break.

When the bike dies, it may sputter, then pick up once, but normally it just dies like somebody turned it off.

If my guy is at his shop today, I'll go get a pair of coils, a spare Zener, and I need a brake switch anyway.

It sounds like a thermal induced electrical problem to me. Only real way to find it is run it until it dies, then do the detective work.....of course, it won't die if it knows you are close to home with a battery of diagnostic tools.

Slick

Bill,
I would try disconnecting the 2MC capacitor. These are notorious for failing even if it is a "new" Lucas part. With the vibration of a P11, the lifespan of the insulating film is likely less than in a Commando. I remove or disconnect them from any Commando or P11 that I install an electronic ignition. Unless you plan on running with no battery, they are more trouble than they are worth.

If you've already replaced everything but the coils, what's stopping you from eliminating the one thing that's still a possibility (probability)?

BillT
What HT plug wires are you using? Are you using Copper core?
Just checking.
CNN

Heat softens insulation to free broken wire to separate fully. Not a bad id to look around after dark pokeing and tugging for revealing flash of insight.

No real talk about checking the Ground point at frame for corrosion. Then after undoing/cleaning up with a dab of oxyguard paste tighten down good then check fuseholder for same oxidations etc. Boyers need a strong ground. The MK 1V black box may or may not fire at plugs unlike your ealier model which will by turning ignition switch on/off repeatedly. Oh ,did I say ignition switch ? Original Lusac junk thing. Try a modern switch or even a toggle to determine the source of your woes and if she ranges about forever then the switch ? Eliminate the blue can too. :|

Just finished changing the coils out. Nice, strong spark. Will take it out tomorrow for another ride around the neighborhood, see if it dies when warmed up.

Discussed the Zener with Wes. His thought is if the zener is bad, I'd be blowing out lightbulbs. Picked up a good used one from his stash while there. The new replacements look downright ugly and very flimsy.

Not zener diode. Clean more connections. Coils can suffer from overtightened clamps/crushings. Usually work or don't.

Torontonian said:

Not zener diode. Clean more connections. Coils can suffer from overtightened clamps/crushings. Usually work or don't.

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+ 1

Slick

Torontonian said:

Not zener diode. Clean more connections. Coils can suffer from overtightened clamps/crushings. Usually work or don't.

Click to expand...

Coils can develop internal shorts which reduces the voltage to the plugs, it could work OK with a fully charged battery, but fail to get the bike started when the battery voltage is lower.

Jean

Re: Another ignition issue - SOLVED

Bike is apparently fixed.

Got home from work today, backed the Ranger out, fired right up and spent a half hour running around the neighborhood.

No issues, and the stumble I would occasionally get around 4000 RPM seems to be gone.

Next time I have an issue where one of these bikes dies, I'll feel the coils while the bike is freshly dead. One coil hotter than the other would indicate an internal short.

I'll run it around locally for the next week before trying any road trips.

BillT my respects to tolerate P11 vibration over the long hauls, implies you're pretty tough or pretty desperate for a Norton fix injected to the bone. I can so relate to the sense of faith to take off a good ways after mysterious show stoppers I'm not really sure I found and fixed everything lurking. One of my great past pleasures after a hard day at school in a city was to hop on and just zoom around feeling and sounding like king of the road, now in Ozarks get too scared to be joy riding near dusk.

hobot said:

now in Ozarks get too scared to be joy riding near dusk.

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A white tail deer can really mess up a nice ride.

Of course, the deer down here aren't that big and are getting pretty scarce:


Those little legs can't get them out of the way of cars, and they don't stand a chance.