Commando Suddenly Won't Start (2014)

Status
Not open for further replies.
Nater_Potater said:
A points-type ignition builds voltage "slowly" enough that it's voltage won't get high enough on a disconnected plug wire to cause serious damage to the coil, whereas a typical electronic ignition either:
1) causes a rapid-enough voltage spike that it can get a spark to jump through the insulation inside the coil. Once that happens, you have a carbon trail that is a short to ground, or
2) Creates enough EMF in the brain box that the somewhat fragile electronic devices get fried.

Nathan
Click to expand...


1) These old coils are not high enough voltage to do that.

2) No brains, just some electronic devices. Proven robust.


The Boyer and Lucas coils will not be damaged if a spark plug slips off the head during checking for spark by kicking.
 
www.accessnorton.com

Pazon Sure Fire Ignition Misfire???

My engine is now stuttering/missing upon acceleration. I thought I had set the carb needles too rich causing a stutter type misfire on my 850 Commando after replacing a worn throttle cable. I figued I would try a litte richer mixture to see if it would run better.so when I was replacing worn...
www.accessnorton.com www.accessnorton.com
 
When a plug wire is disconnected and the spark is not powerful enough to discharge internally through the coil insulation then it will create a kickback voltage that is seen by the output transistor in the module. Will it be high enough to damage it? Maybe -maybe not but most coil driver transistors are rated at 150 volts or so and the kickback voltage can easily reach this high. The damage may not show up immediately.

I wouldn't advise pulling the plug wire without supplying some place for the spark to go. Jim
 
[quote="Nater_Potater][/quote]

A points-type ignition builds voltage "slowly" enough that it's voltage won't get high enough on a disconnected plug wire to cause serious damage to the coil, whereas a typical electronic ignition either:
1) causes a rapid-enough voltage spike that it can get a spark to jump through the insulation inside the coil. Once that happens, you have a carbon trail that is a short to ground, or
2) Creates enough EMF in the brain box that the somewhat fragile electronic devices get fried.

Nathan[/quote]

+1

Lost an early Boyer exactly that way.
 
L.A.B. said:
http://www.accessnorton.com/pazon-sure-fire-ignition-misfire-t5783.html
Click to expand...


Totally apples and oranges.

I was outlining a field cursory check for spark where both plugs are inserted into the leads and grounded, the engine rolled over by the kicker.

The link above is about a person with a Pazon tuning his carbs by DISCONNECTING one lead and STARTING the engine. The OP there never came back and closed the stories loop.
 
"
Lost an early Boyer exactly that way."

WHAT way? The entire story please...
 
"I wouldn't advise pulling the plug wire without supplying some place for the spark to go. Jim"

Agreed, sound advice.
 
judah said:
soooo… i checked the wires going from boyer box to stator. looked fine. wiggled them a bit down where they enter the crank case… gave a kick and boom… fired up first kick. and seems to run fine.

so now. what does it all mean? leads me to believe theres a bad wire or connection somewhere there. what to do next???

also, if I'm riding and this mysterious disconnect disconnects, do you think the bike will just die?
Click to expand...


Yes, the bike will die again, they don't heal themselves. What it all means, to summarize, as others have pointed out, and through your testing (GOOD JOB BTW! :mrgreen: ) it appears you have an intermittent open circuit in one of the trigger leads to the Boyer trigger plate. TWO known pattern failures are: A) the two conductor cable that runs down the frame and enters the back of the timing chest (formerly for the contact breaker points) flex continually due to the engine's iso mounts allowing considerable movement. And B) The wires from or ON the pickup plate may have breaks in the conductor, hidden by still intact plastic insulation. They flop around due to vibration and can break. Have a look here: replacing-boyer-leads-t17499.html Two good places to check for intermittent continuity.
 
concours said:
L.A.B. said:
Click to expand...


Totally apples and oranges.

I was outlining a field cursory check for spark where both plugs are inserted into the leads and grounded, the engine rolled over by the kicker.

The link above is about a person with a Pazon tuning his carbs by DISCONNECTING one lead and STARTING the engine. The OP there never came back and closed the stories loop.
Click to expand...

The result is the same, the coil HT is still being isolated from ground either way.
 
concours said:
"
Lost an early Boyer exactly that way."

WHAT way? The entire story please...
Click to expand...

I was trying to identify a slight miss at idle by pulling plug leads one at a time. I used to do this often with car and boat engines ( all points -coil type).

Pulled one plug lead (R/H) with motor running. No problems and a solid idle one cylinder. Pulled the left lead, again, solid idle one cylinder for a few seconds then the motor died and would not restart. The boyer "box" had died. As soon as the spark had no where to go it died. I am aware of another Boyer that went the same way.

If you need to pull a lead to check spark, always make sure you have a plug in the lead well grounded.
 
"If you need to pull a lead to check spark, always make sure you have a plug in the lead well grounded."

Good plan :mrgreen:
 
My bag of tricks includes a stout length of wire with good clips on both ends that are big enough to hold a spark plug. It makes it a pretty easy job to ensure the plug is grounded and you can even lay it somewhere besides on the head so that it is easier to see. Pretty simple tool to build, comes in handy a lot.

Something like this:
http://www.newark.com/mueller-electric/ ... P=KNC-GPLA

Russ
 
all sound like good tips. thanks.

just to update, like i said, just as suddenly as it refused to start, it started - after fooling around with wires. so i started it up, traced all the ignition wires, and went rustling around the to see if i could find the culprit. after a bit of gentle wiggling and pulling here and there, one of the wire connectors just fell off and the engine died. the metal conducting portion on the inside was all brittle, cracked to pieces and broken. I'm guessing that was it.

I've noticed this on quite a few of them. some of them are 42 yrs old, so no surprise.

would be good to have extras around. anyone know a good source of female-female connectors that work well for norton wire ends? id like to get a box of them.
 
Commando Suddenly Won't Start (2014)


Commando Suddenly Won't Start (2014)
 
Glad you found the issue. While you are going through it, I'd check the stuff folks have mentioned. Sooner or later it will catch up with you and being proactive instead of reactive will pay off.

Scott
 
comnoz said:
You found the problem. The wire is likely broken somewhere or the connector under the cover is loose.
Find it and fix it or you will be walking again soon.
After you fix it then fold a paper towel up under the cover to hold the wires snug and keep them from shaking. Jim
Click to expand...
Sorry for picking up this old thread but I believe the same thing has just happened to my '72 Combat that suddenly began cutting out and then will not start at all and has no visible sparks (although it will catch very occasionally but that might be the wire momentarily arching with all the kickstart activity?) My questions do I need any particular grade of wire to the Boyer to replace the broken one or both to the stator and how would the paper towel wrap round the wires to stop vibration?
 
PM999S said:
how would the paper towel wrap round the wires to stop vibration?
Click to expand...
The thin wire has inertia, as the engine vibrates the wire lags behind and bends with the vibration, eventually the wires fatiques and breaks. A piece of foam or kitchen roll locks the wires to the engine so the wires vibrate in sync with the engine.
 
kommando said:
The thin wire has inertia, as the engine vibrates the wire lags behind and bends with the vibration, eventually the wires fatiques and breaks. A piece of foam or kitchen roll locks the wires to the engine so the wires vibrate in sync with the engine.
Click to expand...
Thanks Eddie, I've ordered a new length of wire from Boyer and will do that mod when it arrives.
 
Status
Not open for further replies.

Similar threads

N
850 Commando won't start, just quit - mid ride.
2
Replies
24
Views
1,290
marshg246
marshg246
C
2019 Norton Commando 961 won't start
2
Replies
31
Views
2,173
Stu Bodycote
Stu Bodycote
A
  • Locked
I suddenly feel very old
2 3
Replies
51
Views
3,396
KiwiShane
KiwiShane
Woody850
  • Locked
New Rebuild won't start
2 3
Replies
42
Views
2,575
Woody850
Woody850
Tornado
  • Locked
So There I Was When Suddenly...
2
Replies
38
Views
2,798
Mart UK
Mart UK
Back
Top