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coils #785793 09/29/19 4:27 pm
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JDH Offline OP
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Morning , My 74 850 Norton has been running erratic . while checking for loose owiring I noticed the one coil warm and the other cold. They both have power to them . They are 6 volt . both show 1.9 ohms. Is it done Thanks for any help
jerry

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Re: coils [Re: JDH] #785797 09/29/19 5:12 pm
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kommando Offline
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Assuming points ignition and the engine not running then the coil being fed by the closed points will be warm, cool with open points will be cold.

Re: coils [Re: kommando] #785799 09/29/19 5:37 pm
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JDH Offline OP
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Thank you I just figured that out by turning engine to open other points,. Can an old battery cause poor running on points. Seems to charge up ok but when engine starts it runs ok til excess gas from tickle and choke are used and then idles rough like water in gas or revs a bit sometimes dies. Carb cleaned 4 times, new plugs twice, on points. Took off Boyer and went to points but same symptoms. Seems sometimes runnig one cylider then 2 and back and forth. Wont stay at one problem long enough to determine cause. I am thinking carbs passing to much air at idle so i cannot get an ajustment. Any thoughts? All i did during last winter was pull timing cover to have oil pump serviced and problems developed shortly after in june. So the triumph got more miles.
jerry

Re: coils [Re: JDH] #785802 09/29/19 5:43 pm
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kommando Offline
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I would be looking at the condenser pack, if you have excessive sparks at the points then you need a new condenser pack. Also look at the earth path route from engine to battery as especially on a rubber mounted engine this must be direct and in good condition, I add a second wire just to be 100% sure.

Re: coils [Re: JDH] #785804 09/29/19 5:47 pm
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quinten Online Happy
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yes , what Commando said .

but also ... 6 volt coils should also be receiving power through a ballast resistor ...
shared by both coils ... wired between the ignition switch and the coils .

the harnes and coils used for 74
were engineered with the anticipation of a starter motor not fitted until 1975 .

if the ballast is bypassed or missing
both 6 volt coils will run hotter when running
and 1 hotter than normal ... with just the ignition switch on .

If the erratic Behavior only starts after warm up
is could be at heat-related coil failure ... maybe .

Re: coils [Re: JDH] #785805 09/29/19 6:02 pm
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Did you poke something through the pilot jets, to clear them?

Last edited by triton thrasher; 09/29/19 6:03 pm.

Amateur Loctite enthusiast.
Re: coils [Re: JDH] #785824 09/29/19 10:12 pm
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Yes, if the idle jet/passages are clogged up from old gas left in them, you will be trying
to run them on the needle jets - and this gives dog-like and quite erratic running !!

You can clean them and clean them and clean them, and it seems to make no difference.
So clean em again.

Ask me how I know this.
There was no internet to ask back then, so I bought a new pair of Amals.
And then carefully examined the old carbs to see why there was such a wondrous improvement.
Getting those idle passages truly clean sure makes a difference...

Re: coils [Re: JDH] #786025 10/01/19 8:54 pm
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JDH Offline OP
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Originally Posted by kommando
I would be looking at the condenser pack, if you have excessive sparks at the points then you need a new condenser pack. Also look at the earth path route from engine to battery as especially on a rubber mounted engine this must be direct and in good condition, I add a second wire just to be 100% sure.


All grounds ok It has been on a Boyer for last 18 years.. It was replaced 4 years ago with a Boyer marc iv. After oil pump service last April I reassembled and strobe timed. It went about 30 miles then it started to run like water in gas, barely took me the last half mile. Drained the gas completely and cleaned the carbs, fresh gas and no joy. Suspected Boyer so did every test I could find. I sent it away and was considered ok. Consulted the Boyer company. Reinstalled but no different . So I swapped coils ,no difference . Cleaned carbs again with my super stinky cleaner3 more times during this time. I used a guitar string to probe the air pulled every time and compressed air. I put my old Boyer back on and it seemed better but did the erratic idle poor running again. So put the new points in but after a minute of running on the tickle an choke start up it went back to running poor . The battery is old i tried another from the triumph , no diff. Would that make any diff anyway? So would carb slides now be the culprit. It ran great for the last 18 years. No I don,t want to sell it๐Ÿ˜Š but appreciate any help.
jerry

Last edited by JDH; 10/01/19 8:55 pm.
Re: coils [Re: JDH] #786026 10/01/19 9:39 pm
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Low or weak battery can make leccy ignition play up,or refuse to play, but if your alternator is up to snuff it should pump out enough volts to be good.
If you've tried a diff better battery it should rule that out
Can you put a voltmeter etc across the battery at idle and see what is there. ?

Over the years I've kept a 2nd or even 3rd bike in the garage for when you have days like this,
but you don't expect it to extent to weeks or months !

btw, have you checked that the main jet(s) haven't undone themselves, and both needles are clipped in place on the slides.
And that both carbs little fuel filters on the inlet will flow fuel.
It doesn't take much to be totally out of spec and give poor running.

Re: coils [Re: JDH] #786129 10/03/19 6:21 am
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Hi Jerry, have you tried by passing the ignition switch?? I had that one cylinder then two then one under about 3000 rpm when I first got mine and it turned out to be the ignition switch. Won't cost anything to try!!

Re: coils [Re: Tiger Shark] #786142 10/03/19 11:21 am
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JDH Offline OP
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Thanks for the support, will have some time tomorrow i hope. Yes it is good to have another bike insured to ride but if i go and ride tomorrow the Norton will have sit there looking sad
jerry

Re: coils [Re: JDH] #786178 10/03/19 9:17 pm
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Anyone who rides a brite bike should carry a jumper wire in his pocket for when the switch h goes bad. I have seen every symptom you can imagine.

Like its said, bypass the switch and see.


Rich (last remaining member ThreeMustGetBeers)
"It's not always about going fast. Sometimes it's nice to slow down" (Wendy E.2016)

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Re: coils [Re: JDH] #786180 10/03/19 10:36 pm
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Rohan Online Content
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Having a heavy set of keys that can jangle in the switch does them no good either,
keep it as light as possible. ?

I'd agree, strike while the iron is hot, and sort it out and get mobile.
(Or, get another Norton to keep it company !?)

Re: coils [Re: JDH] #786190 10/04/19 12:18 am
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koan58 Offline
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Quote JDH

"It has been on a Boyer for last 18 years.. It was replaced 4 years ago with a Boyer marc iv. After oil pump service last April I reassembled and strobe timed. It went about 30 miles then it started to run like water in gas...Suspected Boyer...sent away, was considered ok.. Reinstalled but no different . So I swapped coils ,no difference...put my old Boyer back on... but did the erratic idle poor running again. So put the new points in but after a minute of running on the tickle an choke start up it went back to running poor . The battery is old i tried another from the triumph , no diff. Would that make any diff anyway?"

Is it a pre-electric start bike, ie kickstart only?

Running EI, were the 6V coils in series, with NO ballast resistor? A pre-electric start bike will be perfectly happy with this arrangement and may well have been the setup for the 18 years (I would do without the ballast resistor if it were superfluous)
or were the coils in parallel with a ballast resistor in their common supply? This would be the arrangement for an electric start bike as pointed out by Quinten (though I don't know if it was used prior to electric start, as it would be superfluous apart from allowing 6V coils to be used on a 12V system).

Having returned to the original points system, the 6V coils must be in parallel, supplied with the ballast resistor. A pre-electric start bike will work just as well with 12V coils in parallel WITHOUT a ballast resistor.

So what was the arrangement with EI, and what is the arrangement now having reverted to points? Was there a ballast resistor in the EI setup? and is there one in the current points setup?
This is important to know.

1.9 ohm is reasonable for a 6V coil primary resistance, and as you swapped them to no effect, suggests they are servicable, or at least function for some time from cold.

If the coils are correctly wired for the present setup and the timing is correct, then I agree that the carbs need further investigation, though even stubbornly blocked pilot jets should not prevent reasonable running at say 1/2 throttle.

Re: coils [Re: koan58] #786204 10/04/19 8:19 am
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Originally Posted by koan58
This would be the arrangement for an electric start bike as pointed out by Quinten (though I don't know if it was used prior to electric start, as it would be superfluous apart from allowing 6V coils to be used on a 12V system).


The ballast resistor and 6V coils were fitted to Commandos from 1971 (when the factory originally intended to fit an electric starter but it didn't happen) so well in advance of the (1975) the electric start 850 Mk3 model.

Re: coils [Re: JDH] #786206 10/04/19 10:04 am
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The Commando's with 6V coils had a ballast as they were wired in parallel, without the ballast they would have seen 12V not 6V and not lasted long. With Boyer and other EI the 6V coils are wired in series so they each see 6V and no need for the ballast.

Re: coils [Re: kommando] #786211 10/04/19 12:07 pm
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triton thrasher Offline
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Originally Posted by kommando
The Commando's with 6V coils.... ...were wired in parallel,


Yes, but in separate contact breaker circuits.

The important bit is each one was in a 12 V circuit.



Amateur Loctite enthusiast.
Re: coils [Re: kommando] #786213 10/04/19 12:21 pm
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JDH Offline OP
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As to the last few comments , thank you. The EI's were setup as per instructions. With the last Marc 4 ran great until seemingly sudden poor running. The point setup was wired to the book , fires and then within a minute goes rough as tickle choke effect wears off . Some times I can tweek the carbs and then by itself seems to change the setup running rough or running suddenly to 2000 rpm with throttle closed. I am thinking worn slide then causing lean hence rpms. Hope to give it some attention today. Thanks again, jerry

Re: coils [Re: JDH] #786215 10/04/19 12:56 pm
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Jerry, I wonder if the cause of your problem is a non-functional gas tank vent? Try popping the tank cap open, leave it open and start the engine to check.

Good luck,
.. Gregg

Last edited by gREgg-K; 10/04/19 12:57 pm.

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Re: coils [Re: JDH] #786230 10/04/19 6:12 pm
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quinten Online Happy
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i know you've said you've cleaned the pilot circuit a number of times
but it could be a problem of method ?

use a #78 drill bit [Linked Image from cdn.shopify.com]


Twisted with a lighht touch into the pilot jet circuit .
...to extract the gunk from the pilot jet .

its more effective at Gathering the gunk into the drill twists
and breaking up what is left ... offering a better chance at clearing the pilot jet and passage .

pushing the gunk back Upstream with a guitar string .
Doesn't eliminate the gunk ... just its location
, it probably won't dissolve ,( because its often some jelly like stuff that has fallen out of suspension )
and instead will just drop back onto the jet, plonk ... as the idle Jet sucks its little bit of fuel
causing undue frustration about bad coils and such .

the " bit on a stick" can be bought from a number of retailers (see watermark on photo above )
or you can make up the tool yourself (wd40 type spray tube , super glue and the #78 bit )

Re: coils [Re: JDH] #786241 10/05/19 12:45 am
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Hi JDH,
Thanks for your further info.
Did the bike run well for many miles on the Boyer Mk4? (I know you say ~4 years, but did the bike get plenty of use in that time?)
Within the last few years have there been any periods of disuse?

I only ask because you say the problem showed after having re-installed and retimed the Boyer rotor/stator after having the oil pump serviced.
This makes me suspect a connection between these events.
There presumably was an issue that prompted the oil pump service, what was it? and has it definitely been resolved?
If the bike was off the road for some time while doing this, it is quite possible that the (already ageing) battery has deteriorated considerably. This is notorious for causing problems with EI, and if the battery is bad enough, with contact breaker ignition also.
The symptoms of a bad battery will always be much more evident at tickover/low rpm, when alternator output is low and so the system relies on knackered battery power.

I think that you should have invested in a new battery in April (even testing with your Triumph's battery didn't really prove anything). It would be worth checking the charging system while at it.

Now to the present contact breaker setup
Are you confident of correct ignition timing?
The coils are now supplied through a known good ballast resistor (it should measure something like 1.9 ohms I'm guessing)?
There are new condensers connected between each LT circuit to ground?
Kommando/LAB will know the recommended values for the above components.
I know you have determined that "all grounds good" but don't disregard Kom's emphasis on the need for a quality (ie ~zero resistance) connection between the rubber-mounted engine and battery +ve. This is essential.

The fact that you describe this problem as sudden, within 30 miles of starting after the oil pump service, is so strongly suggestive of battery failure in the meantime.
The other thought that occurs, is that the oil pump service was maybe prompted by wet-sumping, if so has that been solved? I guess you wouldn't know if you've only done 30 miles or so?
Since then, have you pushed through the poor running at lower rpm to get the motor hot, to see how it performed then at higher rpm?
This would give an indication of whether the ignition system is ok at higher system voltage. But if your battery is that grim, it is possible that the alternator will never cope.

Sorry for the many question marks and assumptions, it is difficult to identify/eliminate causes without detailed details.

Best of luck!


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