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Discussion Starter · #1 ·
Hello, I am a new member to this forum and thank you in advance for any info you can give this newb. I ran late 70's CB-550s for years up until I bought a 1997 VLX 600 to get me to school and back reliably. I have noticed that when cold my bike only runs well with the choke half pulled. I rode it about 10 miles today in maybe 60 degree temp, yesterday as well, and had the same problem, having to goose the hell out of it to not kill engine and get rollin, both times after decent warm up. Yesterday when I got home I let her idle a few minutes and the fan kicked on (which I was looking for to check that the sensors were functioning). I checked ignition coil wires with an ignition test light and it seems the front cyl. spark plug on the right side isn't producing spark, but the other three on the bike are. Do I have a problem with ignition firing info going into the coil, or is the coil shot? I thought when coils go out, it resulted in dead cylinders on both connected spark plugs. If that plug was bad, spark would still get to the plug wire, wouldn't it? The Shadow is a new animal to me, I'm not sure where the problem is. Any info would be greatly appreciated and I thank you in advance.
 

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Ignitions are not in my wheelhouse....sorry.

But welcome to the forum, and I hope you find an answer to your problem.
 

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Welcome to the forum! If it's only on 1 wire, Check your ends on that wire to make sure you have good contact. If that doesn't do it, remove the ends, cut 1/4" off each bare wire end, reinstall plug wire ends, and retry. Also, run a couple tanks of seafoam treated fuel through your carbs to take care of your low rpm problem, probably dirty needles/jets. Double dose the first tank.
 

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The coil fires one side so should fire the other, as above check the spark plug leads and the connections at each end.. are you sure the other side is firing properly, both exhausts get hot?

It sounds like the bike is running lean as well so may have a blocked filter (if it has one) or jets that are not totally clear
 

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Hello, I am a new member to this forum and thank you in advance for any info you can give this newb. I ran late 70's CB-550s for years up until I bought a 1997 VLX 600 to get me to school and back reliably. I have noticed that when cold my bike only runs well with the choke half pulled. I rode it about 10 miles today in maybe 60 degree temp, yesterday as well, and had the same problem, having to goose the hell out of it to not kill engine and get rollin, both times after decent warm up. Yesterday when I got home I let her idle a few minutes and the fan kicked on (which I was looking for to check that the sensors were functioning). I checked ignition coil wires with an ignition test light and it seems the front cyl. spark plug on the right side isn't producing spark, but the other three on the bike are. Do I have a problem with ignition firing info going into the coil, or is the coil shot? I thought when coils go out, it resulted in dead cylinders on both connected spark plugs. If that plug was bad, spark would still get to the plug wire, wouldn't it? The Shadow is a new animal to me, I'm not sure where the problem is. Any info would be greatly appreciated and I thank you in advance.
Should be easy to troubleshoot and fix. You have 2 coils (one per cylinder) and each one has a primary lead and two secondary wires which go to each spark plug to that cylinder's spark plugs. Since 3 spark plug wires show spark and the other doesn't, you could try swapping spark plug wires to see if the dead one changes. Or if you have an ohm meter check the bad wire for continuity. I bet you'll find that you have a bad wire that needs to be replaced. Also don't forget to make sure that supposedly bad wire is firmly seated into the coil socket and the boot is tight. Spiders like to find weird places to build a nest. Wouldn't hurt to pull the coil end of the plug wire and inspect the inside of the coil terminal with a flashlight. ;)
 

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Discussion Starter · #7 ·
Welcome to the forum! If it's only on 1 wire, Check your ends on that wire to make sure you have good contact. If that doesn't do it, remove the ends, cut 1/4" off each bare wire end, reinstall plug wire ends, and retry. Also, run a couple tanks of seafoam treated fuel through your carbs to take care of your low rpm problem, probably dirty needles/jets. Double dose the first tank.
Thanks for the welcome and thanks for the info! I will check the wire in the morning. The bike maybe sat a month and I've been firing it up every day for the last few days just to remind it of it's job and it's been pretty responsive, but still, I'll grab some carb pour in cleaner tomorrow. Hopefully I don't have to pull the carb and really clean it
 

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Discussion Starter · #9 ·
Should be easy to troubleshoot and fix. You have 2 coils (one per cylinder) and each one has a primary lead and two secondary wires which go to each spark plug to that cylinder's spark plugs. Since 3 spark plug wires show spark and the other doesn't, you could try swapping spark plug wires to see if the dead one changes. Or if you have an ohm meter check the bad wire for continuity. I bet you'll find that you have a bad wire that needs to be replaced. Also don't forget to make sure that supposedly bad wire is firmly seated into the coil socket and the boot is tight. Spiders like to find weird places to build a nest. Wouldn't hurt to pull the coil end of the plug wire and inspect the inside of the coil terminal with a flashlight. ;)
Thanks for the reply. I'm with you so far as swapping the wires going to the front cylinder. To check for continuity at the plug wire with an ohm tester, do you mean seeing if it has continuity with ground? My understanding of electricity is pretty rudimentary. Tomorrow I will pull the tank so I can get my hands on the coil, make sure connection is good as you and others have mentioned. I'll also see if I can inspect the coil with the wire off. Thanks again!
 

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Discussion Starter · #10 ·
The coil fires one side so should fire the other, as above check the spark plug leads and the connections at each end.. are you sure the other side is firing properly, both exhausts get hot?

It sounds like the bike is running lean as well so may have a blocked filter (if it has one) or jets that are not totally clear
I thought so too. I've never heard of half a coil failing, but what do I know. I'm going to try to get a better look tomorrow. I will check the air filter as well. I put a new K and N in it about 500 miles ago. I've read that might not have been a great idea. As of now I do know both exhausts are getting hot. Hopefully I can get some answers tomorrow
 

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Thanks for the reply. I'm with you so far as swapping the wires going to the front cylinder. To check for continuity at the plug wire with an ohm tester, do you mean seeing if it has continuity with ground? My understanding of electricity is pretty rudimentary. Tomorrow I will pull the tank so I can get my hands on the coil, make sure connection is good as you and others have mentioned. I'll also see if I can inspect the coil with the wire off. Thanks again!
To check the continuity of the spark plug wire, remove the wire connections from the coil and spark plug. Set your meter to the lowest ohms setting or continuity test if your meter has one. Attach one meter lead to one end of the plug wire and the other meter lead to the other end. You should see some resistance reading. Then try flexing the wire looking for breaks particularly around the connectors. If you're familiar with a VOM (volt ohm meter) a loss of a reading should indicate a bad wire and a loss of contact to complete the circuit from the coil to the plug.
 

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Just a quick and dirty test of plug wires from an old auto tech. Just have the engine running and spray water all over the wires and coil areas. You may see an arc-over at the coil terminal or around the head areas or along the run of the wires near insulator stand-offs, etc. It is a fast way to see a weakness especially if you do it at night or in dim light.
Usually you can hear the snapping even if you can't follow the wire.
Good wires don't arc anywhere.
 

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Discussion Starter · #13 ·
To check the continuity of the spark plug wire, remove the wire connections from the coil and spark plug. Set your meter to the lowest ohms setting or continuity test if your meter has one. Attach one meter lead to one end of the plug wire and the other meter lead to the other end. You should see some resistance reading. Then try flexing the wire looking for breaks particularly around the connectors. If you're familiar with a VOM (volt ohm meter) a loss of a reading should indicate a bad wire and a loss of contact to complete the circuit from the coil to the plug.
Thank you. I'll take a look in the morning
 

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Not a bad bike, I take it you checked for spark without removing the old plug, just pulled the cap and fitted a spare plug then held the spare plug against the metal part of the cylinder head with a piece of wood..

If you did the above then the only things to worry about are the lead and plug cap. Replacing both will cost less than a meal and take a couple of minutes.
 

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Discussion Starter · #18 ·
To check the continuity of the spark plug wire, remove the wire connections from the coil and spark plug. Set your meter to the lowest ohms setting or continuity test if your meter has one. Attach one meter lead to one end of the plug wire and the other meter lead to the other end. You should see some resistance reading. Then try flexing the wire looking for breaks particularly around the connectors. If you're familiar with a VOM (volt ohm meter) a loss of a reading should indicate a bad wire and a loss of contact to complete the circuit from the coil to the plug.
Thank you, I will check in the morning!
 

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Discussion Starter · #19 ·
Not a bad bike, I take it you checked for spark without removing the old plug, just pulled the cap and fitted a spare plug then held the spare plug against the metal part of the cylinder head with a piece of wood..

If you did the above then the only things to worry about are the lead and plug cap. Replacing both will cost less than a meal and take a couple of minutes.
I used an Ignition Firing Indicator light. You just hold a button down while the engine is running, put the end near the wire, and it lights up every time there's spark. They all lit up but passenger side front. Today I finally had some time, pulled the seat, got the tank loose, and found that coil is buried deeper than I thought so I'll have to wait until tomorrow to check impedance on it. It's weird though, the thing fires right up, no hesitation.
 

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I don't see any need to check impedance of the coil, you've got a bad plug or wire or connector.
 
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