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sparkplug reading help please

  • Thread starter Thread starter gotjeepzj
  • Start date Start date
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gotjeepzj

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1-4 carbon fluffy deposits. 2-3 electrode is white. I know that 2-3 are hot and I know 1-4 are too rich. Do think it's an ignition issue with 1-4 or 2-3? Plug 4 used to be wet all the time and smelled of gas. It's not now. i've done a coil swap(stock) with new plugs.
 
Air screws

Air screws

It very likely could be something as simple as adjusting your air screws. I'd sure try that before doing anything else. Good luck!:-D
 
Its most likely an ignition issue. You might try just switching the coils. Put each coil on the other pair of cylinders. Keep in mind your 1,4 crank trigger will have to be wired to the coil that is going to fire the 1,4 spark plugs. If the plug colors reverse, you've found the problem. Coil.

Earl

gotjeepzj said:
1-4 carbon fluffy deposits. 2-3 electrode is white. I know that 2-3 are hot and I know 1-4 are too rich. Do think it's an ignition issue with 1-4 or 2-3? Plug 4 used to be wet all the time and smelled of gas. It's not now. i've done a coil swap(stock) with new plugs.
Click to expand...
 
Bear in mind that the two outer cylinders run cooler than the inner ones. This difference is more pronounced if your engine's not getting a decent flow of air through it, like sitting idling or in slow moving traffic. Just a thought.
 
Guy said:
Bear in mind that the two outer cylinders run cooler than the inner ones. This difference is more pronounced if your engine's not getting a decent flow of air through it, like sitting idling or in slow moving traffic. Just a thought.
Click to expand...

I don't idle for long periods of time and my commute to work is on country backroads at 60mph. If that's the case then when not change the 2-3 plugs to a cooler plug?
 
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chuckycheese said:
It very likely could be something as simple as adjusting your air screws. I'd sure try that before doing anything else. Good luck!:-D
Click to expand...

Where are the air screws? How would I adjust them?

Is there a way to test the coils with a multimeter?
 
Air screws

Air screws

The air screws are such a simple fix...and often just what you need. Before you start messing around with anything else, you need to check that out. If you can't find them on your carbs, drop by a shop and have them point them out and give you some free advice on adjusting them according to the plug colors and idle speed. Their location depends upon which type of carbs you have (I don't know which bike you have).

You don't want to make a simple problem worse by messing with stuff in the wrong order...and that is certainly the place to start. I'm pretty sure switching to cooler plugs is the very LAST thing you'd want to try....It's actually a pretty big deal and should almost never be necessary.

Let us know what you find out!!
 
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1979 1000L. I think the air scre is probably the only screw I see visible on the side of the carb. How should I adjust it?
 
gotjeepzj said:
1979 1000L. I think the air scre is probably the only screw I see visible on the side of the carb. How should I adjust it?
Click to expand...
Be careful because the side air screws can be stiff and the heads strip easily.
Your plug reads suggest a weak coil but it won't hurt to set the air screws correctly. Keep in mind that a weak spark will effect combustion and also effect adjusting the screws using the highest rpm method. Worth a try though. You may find them way off.
Set the air screws initially to 1 1/2 turns out from LIGHTLY seated.
Adjust throttle cables play correctly.
On the centerstand, warm up the bike fully.
Set idle to 1,000 rpm by using the idle adjuster knob.
Starting at any carb, slowly turn a screw in either direction until you hear the rpm's max. Fine tune. When you hear the rpm's stop rising, stop turning. Now re-set the idle to 1,000 rpm by using the idle adjuster knob. Repeat this adjustment to the other carbs. On a correctly tuned/maintained bike, the air screws generally end up between 1 1/2 to 1 3/4 turns out.
 
And don't try cooler or hotter plugs. That's just trying to mask a problem. Anything close to normal riding, as you described earlier, will require the stock plugs...NGK B8ES.
 
gotjeepzj said:
Where are the air screws? How would I adjust them?

Is there a way to test the coils with a multimeter?
Click to expand...

Do earls test first. dont touch carbs unless you are sure you must. Have you been doing any carb adjusting just before the problem arose???? It is not often that carbs just go out of adjustment on thier own.
 
The problem is most likely electrical related. It would be easy to check if you swapped coils. Clean your plugs and see if the burn with the coils swapped causes the particular plug burn pattern to move to the opposite cylinders. If it does, there are likely TWO problems as you shouldn't be seeing white plugs. THIS needs to be investigated before operating the bike too much.
 
KEITH KRAUSE said:
Your plug reads suggest a weak coil but it won't hurt to set the air screws correctly. Keep in mind that a weak spark will effect combustion and also effect adjusting the screws using the highest rpm method. Worth a try though. You may find them way off.
Set the air screws initially to 1 1/2 turns out from LIGHTLY seated.
Adjust throttle cables play correctly.
On the centerstand, warm up the bike fully.
Set idle to 1,000 rpm by using the idle adjuster knob.
Starting at any carb, slowly turn a screw in either direction until you hear the rpm's max. Fine tune. When you hear the rpm's stop rising, stop turning. Now re-set the idle to 1,000 rpm by using the idle adjuster knob. Repeat this adjustment to the other carbs. On a correctly tuned/maintained bike, the air screws generally end up between 1 1/2 to 1 3/4 turns out.
Click to expand...


Thanks for the tip. I am curious how a weak spark would lead to hot cylinders though. When I swapped the coils the person I got the coils from had unsoldered the leads to use on his dyna coils. I resoldered them with the leads from my coils. I didn't pay enough attention to which leads had male or female ends just made sure the colors were correct. In order to test the coils I know i'll have to switch the coil wires, but will the leads switch?

A spark issue would make sense since I've noticed a drop in power since the replacement.
 
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With the info you've provided so far, I was thinking the two "rich" cylinders could be a weak coil and the two "lean", or "hot" cylinders could have a normal spark but actually be running lean due to a mixture problem. Maybe I'm being too broad in my thoughts.
More info please. Is the bike completely stock? Any other symptoms? A higher idle after warm up? Does the idle hang a moment after revving? What kind of fuel mileage, etc?
Have you serviced the points? Set the gap/dwell? Are the points clean, mating/contacting evenly and NOT PITTED? Any pitted points could mean a bad condensor. Are the plug cap lead connections tight and clean? Do you get a good blue spark when viewed in a darker area?
You say you've tried different coils? Have you tried swapping the wiring to the coils and the plug leads to see if the rich and lean plug reads follow the swap? Just swap the wiring at the coils, both hots and grounds and swap 1/4 leads to 2/3 and re-test. Clean the plugs off a little first, check gaps and ride several miles to give the plugs a chance to change, if they do change at all.
This test should show if you have a coil problem. But be sure the points are serviced too and also check ignition timing while you're down there.
Let us know what happens and we can go from there.
There are some things to do/check with the carbs that may be involved here but lets eliminate any spark issues first.
 
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