Author Topic: Coil Test  (Read 696 times)

0 Members and 1 Guest are viewing this topic.

Offline ladyrocket

  • Full Member
  • *
  • Posts: 32
  • 1976 Honda CB750F
Coil Test
« on: May 06, 2019, 09:39:27 PM »
Hi guys, finally making some moves on this '76 super sport I picked up 7 years ago and then proceeded to never touch...  I soda blasted and rebuilt the carbs, did a bench sync, adjusted valve tappets, gapped points, set the static timing, and reset cam chain tensioner.  Then I was looking at my spark plug wires and they looked pretty rotted so I was about to replace those but figured I'd double check the coils.

The previous owner had Dyna 3 ohm coils with non resister wires/caps and DR8EA plugs.  I removed the wires from the coils then tested the coils.  I'm getting 3.7 ohms and 3.5 ohms when measuring between the yellow/blue and the black/white wires on respective coils - which seems ok.  Then I tested the wire leads right at the coil (where the wires plug into the coil) and one coil reads 14.09 kohms and other is infinite...  So at the risk of sounding dumb, I'm 99% sure I need new coils.

I've been thinking of just going to a full electronic ignition anyways (Pamco Ultimate?).

So, can someone confirm I need new coils?  And if so, any opinions on the Pamco Ultimate vs. Basic. vs. Dyna ignitions?  I know Hondaman's is great as well, but leaning toward a no points setup.

Offline bryanj

  • Really Old Timer ...
  • *******
  • Posts: 14,011
  • CB500 Number 1000036
Re: Coil Test
« Reply #1 on: May 07, 2019, 06:35:54 AM »
If you definately have infinite across secondary winding(coil wires) its no good.
Personally dont like electronic as any problem sidlines you totaly and the current draw is higher making charging marginal with lights on unless you are revinng the nuts off it.
Semi Geriatric ex-Honda mechanic and MOT tester (UK version of annual inspection). Garage full of "projects" mostly 500/4 from pre 73 (no road tax in UK).

Remember "Its always in the last place you look" COURSE IT IS YOU STOP LOOKIN THEN!

Offline TwoTired

  • Really Old Timer ...
  • *******
  • Posts: 21,805
Re: Coil Test
« Reply #2 on: May 07, 2019, 09:03:31 AM »
Agreed, if your coil secondaries read infinity, they are broken.  They may actually work, though, as small gaps can be jumped in the circuit, just like the spark plug gap.

Anyway, the stock engine does not need High voltage coils, which draw more power from the charging system than you want to endure.  5 ohm coils are fine, especially with a Dyna S which has them drawing power way longer than the stock point ignition (190 degrees of rotation vs, the Dyna-S (270 degrees of crank rotation).
This is wasted power that could be better used to restore battery voltage after an idle period, where the battery typically drains down.

HV coils don't make the engine produce more power, you need engine mechanical changes to do that, and with high compression comes the need for higher coil voltage.  That's why race engines need HV.

Do have some resistance in the secondary spark circuit, either resistor plugs or resistor caps.  This delays the coil discharge event, leading to long spark duration. (which is a good thing.)  The R plugs are typically 5K ohms.  Stock caps for the CB550 were 10K ohm on all my factory 550s.  And the stock plugs were D7EA, a hotter heat range plug with no resistor.

You'll notice noticeably longer warm up time is needed with the D8 heat range.  I hated those in my 550s.  Far too cold blooded.

Cheers,
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline ladyrocket

  • Full Member
  • *
  • Posts: 32
  • 1976 Honda CB750F
Re: Coil Test
« Reply #3 on: May 07, 2019, 01:31:16 PM »
My buddy brought his old set of stock coils over (he just bought the pamco kit). I tested those and primary/secondary resistance was perfect. Bought some new boots at my local motor sports shop too. Bike started right up! First time I’ve ever heard this bike run in the 7 years I’ve owned it! I’ve got tintops velocity stacks on order so I’ll be making my antipods soon. Still a long list of stuff to complete. Maybe I should start a project thread...

Thanks all for the help!


Sent from my iPhone using Tapatalk

Offline Deltarider

  • Really Old Timer ...
  • *******
  • Posts: 8,126
  • ... but some animals are more equal than others.
Re: Coil Test
« Reply #4 on: May 08, 2019, 05:11:34 AM »
... leading to long spark duration. (which is a good thing.) 
Still unproven. Why don't the two of you, TT and Hondaman, combine efforts and show us ignorants once and for all that 'longer' duration and the beneficial effect it has on output and where in the rpm range this advantage occurs. Hondaman has shown us to have access to an oscilloscope. May I suggest that you guys conduct the test thus that it can be repeated elsewhere on the planet to verify/falsify the findings which has been, as you know, a requirement in science since Karl Popper. As I've stated many times: I'm open for all results. I'm just sick and tired of these vague claims that none of us here are able to either verify or falsify.
Quote
The R plugs are typically 5K ohms.  Stock caps for the CB550 were 10K ohm on all my factory 550s.
Resistance varied for different markets as I've demonstrated more than once with documents. It probably had to do with local legislation on noise suppression.
My recommendation remains the same. Stick to the 5kΩ noise suppression, in either a resistor cap or a plug and you'll be fine. Combining a resistor plug and a resistor plugcap involves the risk of making your ignition less reliable.
Those that state there's a significant benificial effect when you go higher in resistance, have a problem: they have to show it to us. Fair enough.
CB500K2-ED Excel black
"There is enough for everyone's need but not enough for anybody's greed."

Offline TwoTired

  • Really Old Timer ...
  • *******
  • Posts: 21,805
Re: Coil Test
« Reply #5 on: May 08, 2019, 11:52:33 AM »
... leading to long spark duration. (which is a good thing.) 
Still unproven.
Only to you.  Many people understand that the in-line resistance behaves like a valve to slow the energy flow from the coil as a reservoir of stored energy.

...And you still have not dis-proven it, either (which you can't).  Only offered vague personal opinion based on prejudice.

Why don't the two of you, TT and Hondaman, combine efforts and show us ignorants once and for all that 'longer' duration and the beneficial effect it has on output and where in the rpm range this advantage occurs. Hondaman has shown us to have access to an oscilloscope. May I suggest that you guys conduct the test thus that it can be repeated elsewhere on the planet to verify/falsify the findings which has been, as you know, a requirement in science since Karl Popper. As I've stated many times: I'm open for all results. I'm just sick and tired of these vague claims that none of us here are able to either verify or falsify.

And, I'm sick and tired of your luddite claims based on ignorance, that it isn't, in fact, true.  You have no right to manage my time and where it is spent.   If you wish to wallow in your own ignorance, continue to do so, as I'm sure you will.  I seriously doubt you would believe any verification I would provide.  I have an oscilloscope.  But, it's not a storage type and I can't trigger a camera with it.  I would only be able to relate a typed description of what I see.  But, you would never accept that.  Because it's not about facts.  You are NOT open to those, unless you dictate the terms of "acceptable" facts.  Perhaps, if you send me a suitable storage scope, to produce some proof acceptable to you, (putting some skin in the game yourself,) maybe, just maybe you might "See" the effect that is inevitable, as I've seen it many times on the scope myself.

Quote
The R plugs are typically 5K ohms.  Stock caps for the CB550 were 10K ohm on all my factory 550s.
Resistance varied for different markets as I've demonstrated more than once with documents. It probably had to do with local legislation on noise suppression.

What?  Speculation?  Blasphemy! Why should we believe that spurious interjection?
Why don't you PROVE that, instead of offering idle speculation, according to your own standards of proof?   What supports your unproven theory?

My (worthless) recommendation remains the same. Stick to the 5kΩ noise suppression, in either a resistor cap or a plug and you'll be fine. Combining a resistor plug and a resistor plugcap involves the risk of making your ignition less reliable.

And what risk is that?  What quantification do you provide in this matter?   And, what is your proof that there is a risk of any type?  What is the magnitude of that risk?  Do investigate that for us so we may ALL be so enlightened.  Isn't THAT only fair, too?

Those that state there's a significant benificial effect when you go higher in resistance, have a problem: they have to show it to us. Fair enough.
Only fair in your altered state of mind. 

You have access to all the data and formulas that prove the spark duration extension.  You are just too freakin lazy and vindictive to ferret it out with your own feeble mind.  You would rather just #$%*, whine, and moan about it being too hard too for you to fathom.  Far easier to simply deny it's existence.

Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline Tracksnblades1

  • My Son was a collegiate competition Trap, Skeet, and sporting Clay
  • Master
  • *****
  • Posts: 1,854
Re: Coil Test
« Reply #6 on: May 08, 2019, 04:12:40 PM »
http://autoditex.com/page/secondary-ignition-33-1.html

Delta,

The above link includes a properly displayed DIS ignition on an oscilloscope. Properly displaying the inverted discharge of the opposite polarity. I'm sure my old Tektronix can do this if I had the adapter.
Without the adapter I'm pretty sure mine will not show the opposite polarity discharge since the discharges are occurring simultaneously on the running mate cylinder. The new techs scopes have all the gadgets to save, replay, compare, but I have an IPhone that can take videos....🤓

I've touched base on this before too. Without any sarcasm and without regards to RF interference, I pose a query.
When was resistance added to the secondary circuit and Why...?
What are the benefits to resistance in the secondary circuit...? With unleaded fuel..?
Why do light airplanes have resistor plugs 1000k-2500k in addition to complete RF shielding of their ignition systems...?

Age Quod Agis

Offline PeWe

  • Really Old Timer ...
  • *******
  • Posts: 15,567
  • Bike almost back to the 70's 2015
Re: Coil Test
« Reply #7 on: May 09, 2019, 03:06:19 AM »
Pamco Ultimate means with coils right?
I have tried that kit and the coils broke very quick since the screws  that you see and is supposed to thread into your HT leads just went out off the coil placstic housing. I had only tightened the wires with thumb and index finger to be sure the wire is attached as deep as possible. 2 wires just popped out with the screw on it gping thru the pastic. Pamco unit  for 2-3 popped when I changed to my old stock coils that have worked in the 80's.

Tried  Dyna3 ohms with Dyna S   and did not like how quick the battery drained with headlight on for a 30 mintues ride mostly over 4500 rpms.
Changed to Dyna 5 ohm coils.  Later back to good stock points and Hondaman ign module, still Dyna 5 ohm coils.

Dyna coils have one weakness,  you must ensure that the wires cannot creep out off the auto type connector. strap the wires into frame close to coils after you have ensured they are connected as deep in as possible,
« Last Edit: May 09, 2019, 03:08:59 AM by PeWe »
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967