Author Topic: Spark plug wires  (Read 4658 times)

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Offline mcswny

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Spark plug wires
« on: August 31, 2014, 07:26:09 PM »
So I need to replace my spark plug wires ( on number one, it's been cut and trimmed to much it's now arcing off the head and  unfortunately had to ride 250 miles from the Adirondacks to New York City today) on my cb750 k2. Originally I was going to cut them and splice on new copper core wires but then I remembered the PO installed a pamco electronic ignition on it. So my question is

A. Is it bad to run the copper cored wire with an electronic ignition even through you should be running the graphite?
B. what COULD happen if I did?
c. Is my only other option new coils?
d. any advice is helpful.

Thanks! Tim
1972 CB750 K2
1997 XR600r (street legal)
1975 XL250
198 XR80

Offline BobbyR

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Re: Spark plug wires
« Reply #1 on: August 31, 2014, 08:28:06 PM »
The original wires are or were copper not graphite. you can get splicers from NGK which are said to work well. The spark plug caps have a screw to bite into copper wire not a string with a graphite coating. I have a PAMCO and there is no reason copper would be a problem. If you have graphite wires, that may be an jury rig from the PO. 
Dedicated to Sgt. Howard Bruckner 1950 - 1969. KIA LONG KHANH.

But we were boys, and boys will be boys, and so they will. To us, everything was dangerous, but what of that? Had we not been made to live forever?

Offline mcswny

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Re: Spark plug wires
« Reply #2 on: August 31, 2014, 09:08:06 PM »
Bobby, great thanks. Just wanted to make sure I could stay with copper wires on my pamco.

For the record, there was no graphite wires just wasn't sure if I was supposed to use them with an electronic ignition.
1972 CB750 K2
1997 XR600r (street legal)
1975 XL250
198 XR80

Offline pamcopete

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Re: Spark plug wires
« Reply #3 on: September 01, 2014, 07:36:35 AM »
With any electronic ignition, including the PAMCO, you should use either resistor spark plugs or resistor spark plug caps, but not both with copper core wire. Generally, when using resistor caps, the caps will fail open before the coil fails, so you should routinely check the resistor caps every time you change the plugs and check the caps before you conclude that the coils are bad. Caps are cheaper than coils and a lot easier to replace!  ;)
« Last Edit: September 01, 2014, 07:40:12 AM by pamcopete »

Offline mcswny

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Re: Spark plug wires
« Reply #4 on: September 01, 2014, 08:00:29 AM »

With any electronic ignition, including the PAMCO, you should use either resistor spark plugs or resistor spark plug caps, but not both with copper core wire. Generally, when using resistor caps, the caps will fail open before the coil fails, so you should routinely check the resistor caps every time you change the plugs and check the caps before you conclude that the coils are bad. Caps are cheaper than coils and a lot easier to replace!  ;)

Thanks pamco Pete!
1972 CB750 K2
1997 XR600r (street legal)
1975 XL250
198 XR80

Offline BobbyR

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Re: Spark plug wires
« Reply #5 on: September 01, 2014, 10:55:28 AM »
Try getting that support from Dyna!
Dedicated to Sgt. Howard Bruckner 1950 - 1969. KIA LONG KHANH.

But we were boys, and boys will be boys, and so they will. To us, everything was dangerous, but what of that? Had we not been made to live forever?

Offline PeWe

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Re: Spark plug wires
« Reply #6 on: September 01, 2014, 11:09:35 AM »
Really useful with answers from an experienced guy that know what he's talking about.

About graphite, Dyna sells such wires for their electronic ignition.
Dynatek "Dyna" Wires are made from high grade automotive, silicon jacketed, high tension cable. All wires are supplied with finished spark plug boot ends and loose coil terminals to allow the final length to be determined by the user. Wires are available with a solid copper core for use on older vehicles where electrical interference is not an issue. For use on new vehicles with electronic advance ignitions or other sensitive electronic equipment, use DYNA suppression wires with a high grade graphite core for best performance and electrical noise suppression. Both wire types ensure maximum energy transfer.
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

Offline Deltarider

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Re: Spark plug wires
« Reply #7 on: September 01, 2014, 11:31:27 AM »
What is 'high grade'? Is it maybe the same as 'heavy duty'?
Oh... and graphite core wires on our bikes is a no no.
CB500K2-ED Excel black
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Offline TwoTired

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Re: Spark plug wires
« Reply #8 on: September 01, 2014, 11:45:17 AM »
FYI:
The original wires were steel strand core.  I expect this is for durability when screwing in the plug cap posts into the end of the wire.  Steel will hold up better under the stress, friction, and vibration, and the resistance difference between copper and steel is miniscule in this application. Sales based info claiming lower resistance for copper, while technically true, is a sales tool rather than any real echnical benefit.  Even it it were an ohm per foot difference (it's lower than that), you are only using a short distance wire in both cases and then inserting 5000 to 10,000 ohms in the path!  A drop in the ocean.

It really doesn't matter where you put the resistance in the coil output.  It can be in the wire, the plug cap, the spark plug or in combination.  The total resistance in path to each spark gap should be about 5KΩ if you are running colder spark plugs (such as D8EA), or 10K if you are running hotter spark plugs (such as D7EA).  The determination is based on spark electrode erosion factors and power consumption/heat generation of the coil and spark electrodes.

In theory, iridiums eliminate (or greatly reduce) spark erosion, IF both electrode ends of the spark plug are iridium, ground strap and center.  This is because the erosion is polarity specific, and the SOHC4 system provides opposite polarity to half of its spark plugs.

Graphite is quite brittle, and therefore a boon to the automotive industry, due to their frequent replacement requirements, particularly in the high vibration environments.  Even in cars, they are routinely replaced every 5-10 years.  This is the reason why the type is so readily available.  High turnover and profitability in distribution.  I expect they are cheaper to manufacture, as well.  But, I haven't researched that particular angle.
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 mcswny

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Re: Spark plug wires
« Reply #9 on: September 01, 2014, 11:51:56 AM »

FYI:
The original wires were steel strand core.  I expect this is for durability when screwing in the plug cap posts into the end of the wire.  Steel will hold up better under the stress, friction, and vibration, and the resistance difference between copper and steel is miniscule in this application. Sales based info claiming lower resistance for copper, while technically true, is a sales tool rather than any real echnical benefit.  Even it it were an ohm per foot difference (it's lower than that), you are only using a short distance wire in both cases and then inserting 5000 to 10,000 ohms in the path!  A drop in the ocean.

It really doesn't matter where you put the resistance in the coil output.  It can be in the wire, the plug cap, the spark plug or in combination.  The total resistance in path to each spark gap should be about 5KΩ if you are running colder spark plugs (such as D8EA), or 10K if you are running hotter spark plugs (such as D7EA).  The determination is based on spark electrode erosion factors and power consumption/heat generation of the coil and spark electrodes.

In theory, iridiums eliminate (or greatly reduce) spark erosion, IF both electrode ends of the spark plug are iridium, ground strap and center.  This is because the erosion is polarity specific, and the SOHC4 system provides opposite polarity to half of its spark plugs.

Graphite is quite brittle, and therefore a boon to the automotive industry, due to their frequent replacement requirements, particularly in the high vibration environments.  Even in cars, they are routinely replaced every 5-10 years.  This is the reason why the type is so readily available.  High turnover and profitability in distribution.  I expect they are cheaper to manufacture, as well.  But, I haven't researched that particular angle.

Love it. Thanks TT.

I went ahead and got the NGK splices, new copper wire, resistor caps and should be good to go by the end of the week. Thanks guys.
1972 CB750 K2
1997 XR600r (street legal)
1975 XL250
198 XR80

Offline pamcopete

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Re: Spark plug wires
« Reply #10 on: September 01, 2014, 01:01:17 PM »
Really useful with answers from an experienced guy that know what he's talking about.

About graphite, Dyna sells such wires for their electronic ignition.
Dynatek "Dyna" Wires are made from high grade automotive, silicon jacketed, high tension cable. All wires are supplied with finished spark plug boot ends and loose coil terminals to allow the final length to be determined by the user. Wires are available with a solid copper core for use on older vehicles where electrical interference is not an issue. For use on new vehicles with electronic advance ignitions or other sensitive electronic equipment, use DYNA suppression wires with a high grade graphite core for best performance and electrical noise suppression. Both wire types ensure maximum energy transfer.

Just a few points:

1. Graphite is cheaper than copper.
2. The graphite suppressor wires have about 1K Ohm per foot.
3. The wire length in the CB750 is about 1 foot from coil to plug.
4. The resulting resistance of 1 K ohm is not adequate.
5. When used in an automotive application, the wire is longer and generally resistor spark plugs are also used.
6. Graphite wires are used in automobiles primarily because they are cheaper than copper wires. Has nothing to do with performance. The resistance of graphite is incidental to the low cost.
7. Dyna sells spark plug wires.
8. PAMCO does not sell spark plug wires.
« Last Edit: September 01, 2014, 01:06:11 PM by pamcopete »

Offline mcswny

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Re: Spark plug wires
« Reply #11 on: September 01, 2014, 02:13:30 PM »

Really useful with answers from an experienced guy that know what he's talking about.

About graphite, Dyna sells such wires for their electronic ignition.
Dynatek "Dyna" Wires are made from high grade automotive, silicon jacketed, high tension cable. All wires are supplied with finished spark plug boot ends and loose coil terminals to allow the final length to be determined by the user. Wires are available with a solid copper core for use on older vehicles where electrical interference is not an issue. For use on new vehicles with electronic advance ignitions or other sensitive electronic equipment, use DYNA suppression wires with a high grade graphite core for best performance and electrical noise suppression. Both wire types ensure maximum energy transfer.

Just a few points:

1. Graphite is cheaper than copper.
2. The graphite suppressor wires have about 1K Ohm per foot.
3. The wire length in the CB750 is about 1 foot from coil to plug.
4. The resulting resistance of 1 K ohm is not adequate.
5. When used in an automotive application, the wire is longer and generally resistor spark plugs are also used.
6. Graphite wires are used in automobiles primarily because they are cheaper than copper wires. Has nothing to do with performance. The resistance of graphite is incidental to the low cost.
7. Dyna sells spark plug wires.
8. PAMCO does not sell spark plug wires.

I thought at least in our application the graphite suppression wires were more for eliminating electrical interference from the electronic ignitions, not a cost issue?

This is more for my curiosity and growing knowledge. I got copper fire for $1 a foot from z1, so not complaining on price there!!
1972 CB750 K2
1997 XR600r (street legal)
1975 XL250
198 XR80

Offline PeWe

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Re: Spark plug wires
« Reply #12 on: September 02, 2014, 03:00:10 AM »
OK. 
Disconnect wire from coil
Measure the ohms in the wire-plug connection is on the list then. Must be 5Kohms if non R plug is used, not 5Kohms, use R plug, right?
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

Offline pamcopete

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Re: Spark plug wires
« Reply #13 on: September 02, 2014, 06:25:58 AM »
OK. 
Disconnect wire from coil
Measure the ohms in the wire-plug connection is on the list then. Must be 5Kohms if non R plug is used, not 5Kohms, use R plug, right?

We seem to be saying the same thing. If the one foot of suppressor wire is not adequate, then use resistor plugs or caps. See #2, 3, 4 and 5 above in my short list. If so, then why use suppressor graphite wire in the first place?
« Last Edit: September 02, 2014, 06:32:45 AM by pamcopete »

Offline PeWe

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Re: Spark plug wires
« Reply #14 on: September 02, 2014, 07:21:27 AM »
Without detailed knowledge of ignition systems,.....It's very easy to believe that a graphite conductor somehow is an upgrade superior all other wires.... :)
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

Offline TwoTired

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Re: Spark plug wires
« Reply #15 on: September 02, 2014, 11:04:06 AM »
Without detailed knowledge of ignition systems,.....It's very easy to believe that a graphite conductor somehow is an upgrade superior all other wires.... :)

Yes. ...To the delight of salesmen preying on ignorance for profit.  It is, in fact, inferior, with planed obsolescence.  Not everything newer is automatically better.

However, I will say that the newer high energy ignition systems are better able to tolerate the internal fractures and burn out spaces that occur inside the graphite core wire, by using simple internal arcing.  The standard SOHC4 spark system is NOT in the high energy class, and the charging systems were never designed to include their higher power useage in the system. 

People still pound square pegs into round holes, though.
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 Deltarider

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Re: Spark plug wires
« Reply #16 on: September 02, 2014, 12:56:29 PM »
Graphite is brittle. Even copper wire is brittle (more than most people think btw), but graphite far more. So graphite on our bikes is a no no.
CB500K2-ED Excel black
"There is enough for everyone's need but not enough for anybody's greed."

Offline pamcopete

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Re: Spark plug wires
« Reply #17 on: September 02, 2014, 03:16:13 PM »
The stock points coil has a primary resistance of 4.5 Ohms so when the coil is on, the current would be 14/4.5 = 3.1 Amps, but the coil is only on for slightly more than half the time with a 190 degree dwell angle, so the average current is 190/360 = .53 X 3.1 = 1.64 Amps.

The 17-6903 "Ultimate" coil has a resistance of 2.5 Ohms, so its peak current is 12.8/2.5 = 5.12 Amps but the PAMCO rotor has a 120 degree dwell angle so the coil is only on for 120/360 = .33 of the time so the average current is .33 X 5.12 = 1.69 Amps

I use 14 Volts for the points because the kill switch typically drops about .5 Volt. The transistor in the PAMCO, as in all electronic ignitions, drops about 1.2 Volts so I use 14.5 - 1.2 - .5 = 12.8 Volts for the PAMCO.

So, the PAMCO uses just .05 Amps more than the stock points system. The operating current for the electronics in the PAMCO is less than .01 Amps, so if we add that into the total it comes out to .06 Amps more than the stock points system per coil, or a total of .12 Amps for both.
« Last Edit: September 14, 2014, 08:50:31 AM by pamcopete »