GL1000, ignition, Dyna, plug leads and induction crossfire


Information and questions on GL1000 Goldwings (1975-1979)
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ned
Posts: 39
Joined: Thu Apr 29, 2010 10:32 am
Location: Sydney
Motorcycle: 1976 GL1000
1986 BMW K100RS
1998 BMW K1200RS

GL1000, ignition, Dyna, plug leads and induction crossfire

Postby ned » Sun Jun 29, 2014 1:39 am



Dear Wing Pilots,

A have been working on my '76 Wing for a few years now in attempt to upgrade just enough to bring it to reliability and permanence of newer bikes. Essentially I am looking for reliability, arent we all :)

So far I've modified the ignition to Dyna pickups and coils, replaced the fuel pump with an electric system and currently I am replacing brake lines and servicing the calipers. The first two were essential because PO simply bandaged all the problems and fixed nothing.

Despite the complete ignition rebuild here was a long term problem with the system. It tended to randomly ping or miss... especially at steady speeds around the suburbs. It was of a concern and therefore I could not go for very long rides.

I blamed my ability to time the ignition statically as well as use my flaky timing light. After several attempts it finally dawned on me to look at the leads and the way they are routed from the coils to spark plugs. They were parallel and touching for a considerable distance on both sides.

Essentially a magnetic field is established around each lead as it fires and induces a spark into the neighboring wire(s). It results in premature detonation, i.e. detonation in two cylinders at the same time. This is, at best counterproductive, and at worst it can damage the rings or the piston. see http://www.jasperengines.com/pdf/SparkPlugCross-FireTB.pdf

To eliminate induced crossfire I separated leads and the problem disappeared.

After reading lot of posts, it occurred to me that few of you may have a similar problem. It costs nothing to fix and it takes just a few minutes to test. Just separate the leads and make sure they do not touch. Leads separators may be a good investment.

I took the bike for a ride and all the problems disappeared. The bike is very responsive and she runs smoothly.

A couple pics to show what I did and why.

Ned
Attachments
temporary zipties holding leads apart.
temporary zipties holding leads apart.
it appears that this is a common problem with the V8s
it appears that this is a common problem with the V8s



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Fred Camper
Posts: 1152
Joined: Sun Aug 16, 2009 9:15 pm
Location: Metro Detroit, MI
Motorcycle: 1977 GL1000, 1976 LTD GL1000

Re: GL1000, ignition, Dyna, plug leads and induction crossfi

Postby Fred Camper » Sun Jun 29, 2014 9:02 am

Thank you Ned. Not sure why I can run OEM routing and you must separate? What kind of ignition leads do you run? I just use the universal set Dynatek sells.

User avatar
ned
Posts: 39
Joined: Thu Apr 29, 2010 10:32 am
Location: Sydney
Motorcycle: 1976 GL1000
1986 BMW K100RS
1998 BMW K1200RS

Re: GL1000, ignition, Dyna, plug leads and induction crossfi

Postby ned » Sun Jun 29, 2014 4:16 pm

Fred Camper wrote:...Not sure why I can run OEM routing and you must separate? What kind of ignition leads do you run? I just use the universal set Dynatek sells.


I use Bosch leads because I can get them in a correct length in my local store. They are a normal carbon based leads used for most auto applications. I did read that Dyna requires such resistive leads, or if you are using solid copper you need a resistor based spark plug.

OEM routing using copper wire leads are stiff and can be routed away from each other. Also, they used extra "padding" by putting leads through sleeves/tubing/extra insulators at critical points.

This problem appears to be common where leads are long and routed a long distance. Most car makers tend to use lead separators. These are used mainly to reduce the magnetically induced crossfire as well as make the ignition system look tidy.

I am not sure if:
a. the cross fire is simply a spark generated in the leads them selves due to high voltage output of the coils them selves, or
b. the spike generated in the neighboring wire that triggers the pick up electronics to fire the coil.

Whichever, the problem is induced by magnetic field and I have invested in leads separators to minimize induced voltage.

User avatar
Fred Camper
Posts: 1152
Joined: Sun Aug 16, 2009 9:15 pm
Location: Metro Detroit, MI
Motorcycle: 1977 GL1000, 1976 LTD GL1000

Re: GL1000, ignition, Dyna, plug leads and induction crossfi

Postby Fred Camper » Sun Jun 29, 2014 5:27 pm

I was always puzzled why the gl leads could run that way while I was taught to separate. I did run my dynatek leads back into the Honda sleeves so perhaps the sleeves make a difference?

User avatar
ned
Posts: 39
Joined: Thu Apr 29, 2010 10:32 am
Location: Sydney
Motorcycle: 1976 GL1000
1986 BMW K100RS
1998 BMW K1200RS

Re: GL1000, ignition, Dyna, plug leads and induction crossfi

Postby ned » Sun Jun 29, 2014 6:19 pm

Fred Camper wrote:I was always puzzled why the gl leads could run that way while I was taught to separate. I did run my dynatek leads back into the Honda sleeves so perhaps the sleeves make a difference?


I think that they do. I think two reasons:
a. simple (extra) insulation to minimize arching, and/or
b. to put some extra distance between the leads.

I suspect that this is the cheapest and most effective solution. I am not a electrical/electronics person but I do know that magnetic effects drop off with distance, so the induced current will also be exponentially smaller.

WRT Dyna or other hall effect pickups... I read that they have to be protected with a diode(?) system to stop them from triggering due to induced noise. The protection has limits, ie it can be overcome if the noise is too high. I read that to mean, that random coil trigger can be induced due to false signals arriving to the dyna electronics. In the old days we had a condenser near the points to soak up the coil induced currents and stop the points from burning up. These days things are a little more complicated.

I hope that there is someone with appropriate qualifications to help us understand the Dyna behaviour ... it should help a lot of people construct a reliable system. Unfortunately we don't know what the Dyna circuits look like to make an educated guess.




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