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Old 05-10-2008, 02:04 PM   #1
tylernt
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Default Coil resistance?

My book says my coil resistance should be 4.0 Ohms (+/- 10%) on the primary and 9.5K on the secondary (+/- 20%). Unfortunately, I get 2.9 and 2.7 Ohms (more than 25% off) and 20K to 18K (like 100% off). Any time I use the electric starter on a cold, choked engine, my plugs like to foul. I suspect it's because the starter draws all the juice and there's none left over for my weak ignition system.

However, I think the book might have the wrong specs for my bike's coils. The Haynes covers Yam XS400s from '75 to '84, but only really details the early models with points ignition -- only passing mention is made of the later electronic ignition (which I have) in the last section of the book. The picture of the coils in the book is also way different from what's on my bike. Could the electronic use different coils? Are my Ohm readings so far off that I should consider replacing the coils?
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Old 05-11-2008, 01:19 AM   #2
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I wouldn't judge your findings untill I had factory info. The Haynes manuals try to cover too much and sometimes are a bit misleading. If you can, get a factory manual. It's money well spent. This one is currently $8 plus shp.
http://cgi.ebay.com/ebaymotors/Offic...spagenameZWDVW
If your coils work, I wouldn't worry . Coils can run $65 ea.
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Old 05-11-2008, 11:06 AM   #3
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I agree with RockSolid on that one. IMHO Coils tend to be a work / don't work propostion with very few exceptions. As far as readings, VERY generally I've found coils intended for Points & Condensor systems read about 3.0/4.0 ohms and ones intended for use with Electronic Ignitions read about 1.0/2.0 ohms. Again as stated a specific shop manual will have the correct Multi-Tester readings to look for. IF your concerned about "lack of (electrical) power" I'd definitely do a Voltage output test of your charging system - both under the load of the lights and without. 12.8 to 14.5 DC volts above idle would be deemed acceptable.

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Old 05-11-2008, 03:33 PM   #4
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Well I've bid on that manual so we'll see what it says when it gets here. In the meantime, I'm happy to just keep kickstarting it if it saves me over $100 in new coils. And I thought $60 for a pair of air filters was bad enough...
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Old 05-11-2008, 03:59 PM   #5
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Tylernt, Are you familiar with Ebay bidding? Watch your bid. Chances are you will be needing to bid a little more because somebody else did bid on it. Wait till there is only a minute left and bid the max you would ever be willing to pay for it. Ebay will only use as much of your max as is needed to win it for you. If you don't wait, your opponent will have time to raise his bid again.
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Old 05-13-2008, 03:35 PM   #6
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After reading this thread on “Coil Resistance” I have a question on coil testing with a multimeter.

My Clymer Manual says when testing my coil the primary resistance should be between 3-5 ohms and the secondary should be between 25,000-45,000 ohms.

My confusion with it is the Manual says in Step 1: "Disconnect all ignition coil wires (including the spark plug leads) before testing." Than it says to test the primary circuit.

In Step 3 it says, "measure the secondary coil resistance between the 2 spark plug leads (with the spark plug caps attached)."

My question is attached to what? In Step 1. it says unattach all wires and in Step 3 , " spark plug caps attached"?

Will one of you guys please explain this to "dense" me?

Thanks,

adkron
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Old 05-13-2008, 04:07 PM   #7
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Here's how I tested: unplug the spark plugs and unplug the two wires that go to each coil from the harness (I'll call them "red" and "yellow"). I got one reading from the spark boot to red or yellow, and another reading going between red and yellow.

I think your book tells you to do it with the caps "attached", because the cap can detach from the wires. The caps sometimes have resistors in them, so testing the bare wires without the caps may produce a false reading. So when it says attached, it means caps attached to the wires -- not to the spark plugs.

I think.
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Old 05-14-2008, 01:28 PM   #8
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Thanks tylernet,

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Old 05-15-2008, 02:37 PM   #9
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Hi again tylernt,

I hope you or anyone else can help me with this problem. It is a bit convoluted and I apologize at my attempt to explain what I am doing.

I am attempting to test my coil with a multimeter. A diagram of my coil is available by clicking the link below and than clicking the check mark and going to ELECTRICAL on the drop down menu. http://www.suzukipowersports.com/fic...1992&fveh=2170 . Part number 5 is the coil in question. A test of the primary circuit is within spec i.e. 3.2 ohms – spec is 3 to 5. When I try to test the secondary circuit which places the ohm meters electrodes on one of the primary terminals and the other where the plug wire attaches to the spark plug I don’t get a reading. I also have attempted to place the ohm meters electrode where the plug wire attaches to the coil. However I can’t get the wire off the coil. I am afraid to pull the wire to hard as I may break something. It looks like it is permanently attached. Do you know if there is a way to get this wire off the coil. The diagram does not give the wire a number and it could be a part of the coil? I will attempt to put the diagram on this post.

The reason I am doing this is my number 1 cylinder is not firing. It could be electrical, carburetor, compression, who knows?

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adkron 1992 Suzuki GSX1100G

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Old 05-15-2008, 03:21 PM   #10
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Ok it looks like each coil is firing two spark plugs? Is that right?

So, can you get a reading on the other spark plug wire, or on the spark plug wires for the other coil? If you don't get a reading on any of them, then it's probably supposed to be that way. If it's just that one spark plug wire that has no reading, then something is wrong with that wire or cap.

I'm not sure if/how the wires can be removed from the coil though, hopefully someone else here knows.
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Old 05-15-2008, 03:36 PM   #11
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Hi tylernt,

Each coil fires two plugs. My problem is with cylinder 1 which is the coil numbered 5 in the diagram.

I have tried both the wires on plug 1 and 4 and get a zero reading on both. However cylinder 4 is fine and operating correctly.

I could just get a new coil and hope that solves the problem. I've been experimenting and ordering parts but it's getting expensive.

I can’t get my compression guage to thread into the number 1 cylinder despite many trys. I wonder how the bike shops do it? My gauge is hooked to a rubber hose that is about a foot long. The cylinder is buried under the gas tank and the plug is deep within the head. I'm probably going to have to again remove the gas tank to get the compression gauge into cylinder 1.
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Old 05-15-2008, 04:25 PM   #12
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Well if cyl 4 is firing then the coil should be fine. But I think we need a Suzuki expert here to tell us how to get the secondary winding reading or how to replace that 1 wire.

Yep the tank probably has to come off. Common problem with inline-4s, that's why I like twins.
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Old 05-16-2008, 01:24 PM   #13
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Thanks for the help Tylernt,

I will be taking the tank off again. I agree with you on twins. If I get another bike it will be a 1200 Sportster twin. I'm trying to avoid that kind of expense. This Old Suzuki of mine has been a terrific bike and the problems it's having is my own doing by not paying enough attention to it when I wasn't going to be riding for an extended period of time.

I think I will post a question on how to replace that number 1 wire under the Suzuki section.

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