Correct resistance for ignition parts?


Information and questions on GL1000 Goldwings (1975-1979)
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Rocketman
Posts: 15
Joined: Tue Oct 20, 2009 10:47 pm
Location: Minneapolis, MN
Motorcycle: 1977 GL1000 with bags and Vetter fairing

Correct resistance for ignition parts?

Postby Rocketman » Mon Jun 18, 2012 8:56 pm



My 77 GL1000 is having an issue with fouling plugs during warm-up and occasional backfiring. The plugs only have about 500 miles on them. I adjusted the points and checked the timing in both coils using a timing light and the carbs have recently been balanced. Except for the fouling the bike is running well.

An article on Randakks site says that too high resistance in your ignition system will result in a weak spark, and high resistance in the coil could be a sign of a failing coil. According to the article the correct resistance of the coils secondary circuit is about 24 Kohms when measured between spark plug caps on the same coil (cyl 1 spark plug cap to cyl 2 spark plug cap and cyl 3 to cyl 4). The 24 kohms is comprised of 14 Kohms for the coil itself plus 5 Kohms for each of the two resistors inside the plug caps. When I measured mine I got 36 Kohms on both coils, not 24. I checked a spare coil I have from another 77 GL1000 and it too measured 36 Kohms. Since they all measure the same I'm inclined to think that 36 Kohms is correct, at least for the 77 model.

Does anyone know what the coil resistance is on their 75-77 Goldwing when measured between spark plug caps on the same coil (cyl. 1 to 2 and 3 to 4) ? Any suggestions on getting a better spark and curing my plug fouling?

Mike



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dingdong
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Motorcycle: 1976 gl1000
1993 gl1500
2004 NRX1800 Rune

Re: Correct resistance for ignition parts?

Postby dingdong » Tue Jun 19, 2012 8:25 am

I believe that is higher resistance than it should be which could cause a weak spark. The 77 is the same as the others. The plug wires are screwed into the plug caps. Try unscrewing the wires and cutting off about 1/4 to 3/8 inch of each, clean the screws inside the caps and then screw them back together. They are old and probably loose and corroded. Even the resistors could be corroded inside the plug.
However you could also have some issues with the carbs. You say they have been balanced but have you done any other work with the carbs.
Tom

A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed.

TheArtist
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Joined: Fri Apr 08, 2011 1:13 pm
Location: dell rapids
Motorcycle: 1979 GL 1000

Re: Correct resistance for ignition parts?

Postby TheArtist » Tue Jun 19, 2012 12:45 pm

when i check my 79 this is what i got, the parts were each tested alone. I tried a different coil hoping to be able to change out the wires. It only had 1/2ohm resistant. The bike would not even start.


So decided to check the stock coil, it was 2ohms, the Honda stock resistor, 3 ohms, and the glass one they had read at 2.5 ohms.

Rocketman
Posts: 15
Joined: Tue Oct 20, 2009 10:47 pm
Location: Minneapolis, MN
Motorcycle: 1977 GL1000 with bags and Vetter fairing

Re: Correct resistance for ignition parts?

Postby Rocketman » Tue Jun 19, 2012 6:56 pm

I did cut off the ends of the spark plug wires and reinstall the caps but it did not affect the resistance reading. Somewhere I read that it is possible to remove the resistor and replace it with a piece of a brass screw cut to the same length as the resistor to remove the 5K ohm resistance in each cap. I tried to do that but I couldn't get the resistor out. I finally cut a spare resistor cap in half the long way to see what I was working with and discovered the resistor is molded permanently into the cap. The removable brass screw leads you to think its the type with the removable resistor, but I concluded the purpose of the removable screw is to change sizes to accommodate different spark plug ends. I think I saw on Dennis Kirk website there are three different size plug ends.

The fact that I have three different coils all reading the same resistance makes me think that is the normal resistance. What are the odds that all three would develop high resistance and arrive at the same level? Too coincidental I think.

TheArtist
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Re: Correct resistance for ignition parts?

Postby TheArtist » Wed Jun 20, 2012 9:58 am

The older caps had a screw inside the cap I was able to take out. With showing all the same resistance makes me wonder if your tester works correctly, or on the wrong setting. Maybe bad batteries? With my unit it reqiures batteries for that function.

Rocketman
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Joined: Tue Oct 20, 2009 10:47 pm
Location: Minneapolis, MN
Motorcycle: 1977 GL1000 with bags and Vetter fairing

Re: Correct resistance for ignition parts?

Postby Rocketman » Wed Jun 20, 2012 11:55 pm

Discovered something unexpected. I get about 35 kohms measuring the resistance from one cap to the other, and subtracting 5 kohm for each cap resistor that left the coil at about 24 kohms which is about 10 kohms too high. Tonight I removed the caps and found they each actually measure about 10 kohms each, not 5. The coil resistance is about 14 kohms as it should be.

I have never read or heard about cap resistance being anything other than 5 kohms. Perhaps I should buy a set of 5 kohm caps to get the resistance down where it should be.

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dingdong
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1993 gl1500
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Re: Correct resistance for ignition parts?

Postby dingdong » Thu Jun 21, 2012 6:43 am

Now it sounds like you have the wrong caps. All of the caps for a 1000 I have seen have all had a removable 5k resistors.
Tom

A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed.

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Fred Camper
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Re: Correct resistance for ignition parts?

Postby Fred Camper » Thu Jun 21, 2012 7:23 pm

I have measured the cap resistors on my 1977 and they measure close to 5K, so sounds like someone had a radio issue and tried to use higher resistance caps which is certainly not good for spark. But if you coils are 35 years old, you might consider updating them as next time you are caught in a downpour, any little hairline crack in those coils will let the spark leak out and leave you two cylinders down. Not an inexpensive solution, but I do not like putting my clutch through 10 miles of high rpm launch just to keep the engine running on two cylinders.

Old Fogey
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Re: Correct resistance for ignition parts?

Postby Old Fogey » Thu Jun 28, 2012 7:41 am



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