"dead" spark plug question.
#11
09-12-2010, 06:04 AM
Ultimate HDF Member
New plugs and wires again. Do both as a set and use good plug wires. Also check your wires going to the coil to make sure that you don't have a loose connection. If problem repeats then coil.
Last edited by oldairboater; 09-12-2010 at 06:08 AM.
#12
09-12-2010, 06:08 AM
The plug is bound to be wet with gas if it isn't firing.
I'm on my 3rd stator and still have the stock plug wires. The charging system, provided the battery is charged, has nothing to do with the ignition system.
xfrrebirdx, I'd give the 3rd plug a shot first, but if the problem reoccurs, you may have a coil that's breaking down, or a plug wire with a bad connector crimp. You don't have one of those cylinder bridge inserts installed around the plugs do you? They are known to short (arc) the plug wires to ground.
I'm on my 3rd stator and still have the stock plug wires. The charging system, provided the battery is charged, has nothing to do with the ignition system.
xfrrebirdx, I'd give the 3rd plug a shot first, but if the problem reoccurs, you may have a coil that's breaking down, or a plug wire with a bad connector crimp. You don't have one of those cylinder bridge inserts installed around the plugs do you? They are known to short (arc) the plug wires to ground.
Man I don't even want to think about changing the stator again.
For sure I'm doing that. I have absolutely no ignition toys IE: Bridge inserts, Light up plug wires or the like.
#13
09-12-2010, 06:13 AM
So far the coil has passed all resistance tests in my manual.
#14
09-12-2010, 06:53 AM
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Resistance tests are helpful, but they won't tell the whole story. If the coil fails the resistance test, the coil is bad. If it passes the resistance test, it's probably good. The real test is under load, when there's HV running around in there and stressing the internal insulation.
If you want to put the bad spark plug issue to bed once and for all, you don't need to buy a third plug. Put one of the "bad" plugs in the front cylinder and see what happens. A simple, easy way to confirm or eliminate the plugs as the cause of the problem. If the plugs really are bad, you have to think outside the box and figure out what's destroying rear plugs.
If I had to venture a guess, I'd say you have a bad coil.
If you want to put the bad spark plug issue to bed once and for all, you don't need to buy a third plug. Put one of the "bad" plugs in the front cylinder and see what happens. A simple, easy way to confirm or eliminate the plugs as the cause of the problem. If the plugs really are bad, you have to think outside the box and figure out what's destroying rear plugs.
If I had to venture a guess, I'd say you have a bad coil.
#15
09-12-2010, 07:04 AM
Outstanding HDF Member
i would run a quick simple compression test just to make the rear cylinder wasn't low due to a leaky valve causing the plug to fire over time. low compression will cause wet plugs because all the fuel isn't burning off.
just a side note that popped in my head.. i have a cool OLD coil tester made by snap-on that was made in the early 40's handed down from my grandfather.. it essentialy replaces the dist or control module in grounding and loading the coil. to bad you couldn't find one of those.. probably not though, every snap-on dealer i've ever asked has never seen one..
just a side note that popped in my head.. i have a cool OLD coil tester made by snap-on that was made in the early 40's handed down from my grandfather.. it essentialy replaces the dist or control module in grounding and loading the coil. to bad you couldn't find one of those.. probably not though, every snap-on dealer i've ever asked has never seen one..
#16
09-12-2010, 07:06 AM
Resistance tests are helpful, but they won't tell the whole story. If the coil fails the resistance test, the coil is bad. If it passes the resistance test, it's probably good. The real test is under load, when there's HV running around in there and stressing the internal insulation.
If you want to put the bad spark plug issue to bed once and for all, you don't need to buy a third plug. Put one of the "bad" plugs in the front cylinder and see what happens. A simple, easy way to confirm or eliminate the plugs as the cause of the problem. If the plugs really are bad, you have to think outside the box and figure out what's destroying rear plugs.
If I had to venture a guess, I'd say you have a bad coil.
If you want to put the bad spark plug issue to bed once and for all, you don't need to buy a third plug. Put one of the "bad" plugs in the front cylinder and see what happens. A simple, easy way to confirm or eliminate the plugs as the cause of the problem. If the plugs really are bad, you have to think outside the box and figure out what's destroying rear plugs.
If I had to venture a guess, I'd say you have a bad coil.
Never thought of that
That more than likely will be the culprt......I hope.
Thanks for the insite.
#17
09-12-2010, 07:17 AM
i would run a quick simple compression test just to make the rear cylinder wasn't low due to a leaky valve causing the plug to fire over time. low compression will cause wet plugs because all the fuel isn't burning off.
just a side note that popped in my head.. i have a cool OLD coil tester made by snap-on that was made in the early 40's handed down from my grandfather.. it essentialy replaces the dist or control module in grounding and loading the coil. to bad you couldn't find one of those.. probably not though, every snap-on dealer i've ever asked has never seen one..
just a side note that popped in my head.. i have a cool OLD coil tester made by snap-on that was made in the early 40's handed down from my grandfather.. it essentialy replaces the dist or control module in grounding and loading the coil. to bad you couldn't find one of those.. probably not though, every snap-on dealer i've ever asked has never seen one..
Thats a thought, but the compression is good. As far as all the fuel not burning off I don't think the rear head pipe would be cool to the touch.
Thats funny you said that. My dad who is pushing 80 (and is a motor head)mentioned one of those too. He couldn't remember who had them tho. lol
#18
09-12-2010, 07:29 AM
Outstanding HDF Member
i was just looking for a pic of it.. i knew i had one, a ol motorhead friend in CA couldn't wrap his head around what i was trying to explain to him.. it since got deleted..
you could make one yourself with a old points dist with a fresh set of points in it..
connect point lead from dist to grounding/dist/module side of coil. ground the dist housing to a good bike ground. connect 12 volts to + side of coil. install coil/plug wire and have assistant hold the coil wire approx 1/8"-1/2" from ground or(use a adjustable plug wire tester, the kind that clips onto the eng and plug the wire on the end). spin the dist shaft and you should get a nice blue spark up to a 1/2" or more away. if its a yellow spark and can't get more than a 1/8" or so, the coil is junk..
to load up the coil simulating high load condition, leave the dist points in a "grounded" position for a short period of time untill the coil starts to feel warm, not any longer than 5 minutes or you will burn the coil up.. after the coil gets warmed up spin the dist again and you should have the same spark quality as before when cool..
if you want to spin the dist real fast, you can chuck it up in a drill to give you more a consistent high rpm.
you could make one yourself with a old points dist with a fresh set of points in it..
connect point lead from dist to grounding/dist/module side of coil. ground the dist housing to a good bike ground. connect 12 volts to + side of coil. install coil/plug wire and have assistant hold the coil wire approx 1/8"-1/2" from ground or(use a adjustable plug wire tester, the kind that clips onto the eng and plug the wire on the end). spin the dist shaft and you should get a nice blue spark up to a 1/2" or more away. if its a yellow spark and can't get more than a 1/8" or so, the coil is junk..
to load up the coil simulating high load condition, leave the dist points in a "grounded" position for a short period of time untill the coil starts to feel warm, not any longer than 5 minutes or you will burn the coil up.. after the coil gets warmed up spin the dist again and you should have the same spark quality as before when cool..
if you want to spin the dist real fast, you can chuck it up in a drill to give you more a consistent high rpm.
#19
09-12-2010, 07:41 AM
Resistance tests are helpful, but they won't tell the whole story. If the coil fails the resistance test, the coil is bad. If it passes the resistance test, it's probably good. The real test is under load, when there's HV running around in there and stressing the internal insulation.
If you want to put the bad spark plug issue to bed once and for all, you don't need to buy a third plug. Put one of the "bad" plugs in the front cylinder and see what happens. A simple, easy way to confirm or eliminate the plugs as the cause of the problem. If the plugs really are bad, you have to think outside the box and figure out what's destroying rear plugs.
If I had to venture a guess, I'd say you have a bad coil.
If you want to put the bad spark plug issue to bed once and for all, you don't need to buy a third plug. Put one of the "bad" plugs in the front cylinder and see what happens. A simple, easy way to confirm or eliminate the plugs as the cause of the problem. If the plugs really are bad, you have to think outside the box and figure out what's destroying rear plugs.
If I had to venture a guess, I'd say you have a bad coil.
#20
09-12-2010, 12:04 PM
Pull the 12 volt plug from the coil. With a bright light carefully inspect both both sides of the plug. Do you see any corrosion (green or black) on the pins or sockets? Another thing to check, if you have a lot miles on the engine, is carbon build-up. If there is a lot of carbon in the cylinder, pieces can break off and bridge the gap on the spark plug. When you remove the plug the piece of carbon usually falls off before you can see it.