I did not realise when I put this thread on, what great info it would generate.
Cheers Rob
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Denso spark plug probs
Moderators: KeithZ1R, chrisu, paul doran, Taffus
Its not too easy to tell (better with the blurred images i took) but the tiny dots shown on the central nose insulator 'form up' into several small lines radiating out from or into the central electrode.
This is a miss-firing plug on my bike. One of two the same, and suffered the same fate as the new Denso's i fitted.
Its done about 100 miles or so.
AL
"On Twin tower coils (four cylinders with two coils using a 'lost' spark arrangement) it leaves the coil travels through the head and travels back up the other spark plug back to the coil apparently. "
I think you've been sold a kipper there
What you describe here could only happen if the engine was totally shielded from any connection to earth other than the coil - and even then I'm not sure it would work. With a direct connection between the engine and earth the spark energy will take the easiest path to earth (i.e. the engine block then to the earth lead) and not jump another gap from earth (the engine) at the other plug, connected to the same ignition coil!
The spark leaves the coil, down the plug leads and jumps to earth across the spark plugs electrodes in both cylinders simultaneously - that's it. Full stop.
The proof is easy - when you pull one plug cap off the motor will drop onto 3 cylinders. If the kipper scenario was indeed not a kipper then the motor would drop onto 2 cylinders
I got fed exactly the same story from a Bosch rep who was trying to sell me an engine tuner.
Discuss
I think you've been sold a kipper there
What you describe here could only happen if the engine was totally shielded from any connection to earth other than the coil - and even then I'm not sure it would work. With a direct connection between the engine and earth the spark energy will take the easiest path to earth (i.e. the engine block then to the earth lead) and not jump another gap from earth (the engine) at the other plug, connected to the same ignition coil!
The spark leaves the coil, down the plug leads and jumps to earth across the spark plugs electrodes in both cylinders simultaneously - that's it. Full stop.
The proof is easy - when you pull one plug cap off the motor will drop onto 3 cylinders. If the kipper scenario was indeed not a kipper then the motor would drop onto 2 cylinders
I got fed exactly the same story from a Bosch rep who was trying to sell me an engine tuner.
Discuss
Insert witty comment here.......
The proof is easy - when you pull one plug cap off the motor will drop onto 3 cylinders. If the kipper scenario was indeed not a kipper then the motor would drop onto 2 cylinders Shocked
Agree entirely which is what has me confused.
Possible Kipper!
Might be red herring though!
Have e-mailed Dyna for some light shining.
AL
...........I've heard this one a while back..... But I think there is a system that works summink like that, but I think its an older system & possibly on a car 
Mikey, the extra gap thing is an old trick, and there is a system thats sold at the Brit bike shows, which operates the "extra air gap" principle
Its a bit of a con really - OK for your poor starting senario, but a second best effort - especially if you're daft enuff to pay for the complete system
Mikey, the extra gap thing is an old trick, and there is a system thats sold at the Brit bike shows, which operates the "extra air gap" principle
Its a bit of a con really - OK for your poor starting senario, but a second best effort - especially if you're daft enuff to pay for the complete system And on the 7th day... Zeds were created!
This has been one of the best threads I've read so far! I was trying NGK B8ES, Denso W24ES-U and the Denso Iridiums. I have a Z1A which is set up just about right. I also have a Z900A4 which is running a little rich. What I've found is the using NGK's were fine but started to play up after 1000 miles, Denso iridium's seem to go on and on in the Z1A, in the A4 the iridiums would foul on starting on the A4 so went back to NGKs. Both bikes run fine when plugs are ok.
After reading this thread and learning how these plugs are now made and just how delicate they are with these old engines I have come to this conclusion, unless your engine is absolutely perfectly set up I think using the cheaper plug makes more sense, have spare plugs on hand and just change them when your engine starts to run rough before you do anything else. Because they are so cheap it's not an issue to change the whole set before you start chasing your tail trying to solve what you think is a carb problem, coil problem and so on!!
Just my two cents worth!
After reading this thread and learning how these plugs are now made and just how delicate they are with these old engines I have come to this conclusion, unless your engine is absolutely perfectly set up I think using the cheaper plug makes more sense, have spare plugs on hand and just change them when your engine starts to run rough before you do anything else. Because they are so cheap it's not an issue to change the whole set before you start chasing your tail trying to solve what you think is a carb problem, coil problem and so on!!
Just my two cents worth!
Lost in the desert somewhere
Got this back from Dyna Technical today.
Not sure if it doesnt raise more questions for me but heres what they siad.
The bit i still dont understand i have highlighted.
Perhaps someone can interpret it for me.
Sorry for the delay in responding but I have been in meetings all week which
is why I am replying at this late hour. On to your issue. As you noted it is
pretty much impossible for one cylinder in a firing pair to have different
timing than the other cylinder on that same coil. As far as the ignition is
concerned your 4 cylinder bike is basically a twin. While this is a positive
and negative current flow on the plugs the ground path is still through the
plug threads, engine cases and back to the battery. In my experience with
inductive timing lights you should not have to reverse polarity on the pickup
but no matter what you do you may see some fluctuation depending on the light
and possibly plug wire condition.
And;
I pretty much lost all respect for timing lights a few years ago after
witnessing a high end Snap-on digital inductive timing light malfunction on a
dragbike using our Dyna 4000. The Dyna 4000 is a fixed timing system that in
this case was using a billet timing rotor so timing fluctuations are all but
impossible. However, the timing light was showing the timing bouncing 15-20
degrees at idle and as you revved the engine up the timing mark would just
disappear at about 3000 rpm. After we were done with the troubleshooting it
was discovered that the timing light was triggering off both the leading and
trailing edges of the trigger signal at idle and as the rpm increased it
started triggering from the adjacent cylinder that it was not even connected
too! That was pretty much the last time I used a timing light. I do all my
timing statically now.
Anyone?
AL
On a P.S. to the spark plug part of this thread, i spoke to a guy called Tim from the Green Spark Plug company the other day.
Whilst he admits that he is not a technical person he did say that the problems of early fouling and intermittent running are universal in older engines these days.
Particularly those which need 'flooding' of the carbs prior to cold starting and those that run primitive oil control piston ring setups.
All his customers are getting the same thing and he gets at least five to ten calls every day with the same scenario spelled out by owners of different vehicles.
He sympathised and could offer no viable alternative but he did suggest that this has been a deteriorating situation which in his experience has only come about with changes in fuel composition over the last ten or fifteen years due to the arrival of modern lean burn engines.
On a practical note he said that you should not allow the engine to idle on choke, dont flood to start, get the engine properly hot as soon as possible, maintain it in the best condition possible and change your plugs often and this he suggested to be at every 2000 miles.
He also made a big point about never cleaning the plugs because it kills them instantly.
He didnt offer any other manufacturers products as alternatives and when asked he suggested either; wait for it............... NGK or Denso.
Not sure if it doesnt raise more questions for me but heres what they siad.
The bit i still dont understand i have highlighted.
Perhaps someone can interpret it for me.
Sorry for the delay in responding but I have been in meetings all week which
is why I am replying at this late hour. On to your issue. As you noted it is
pretty much impossible for one cylinder in a firing pair to have different
timing than the other cylinder on that same coil. As far as the ignition is
concerned your 4 cylinder bike is basically a twin. While this is a positive
and negative current flow on the plugs the ground path is still through the
plug threads, engine cases and back to the battery. In my experience with
inductive timing lights you should not have to reverse polarity on the pickup
but no matter what you do you may see some fluctuation depending on the light
and possibly plug wire condition.
And;
I pretty much lost all respect for timing lights a few years ago after
witnessing a high end Snap-on digital inductive timing light malfunction on a
dragbike using our Dyna 4000. The Dyna 4000 is a fixed timing system that in
this case was using a billet timing rotor so timing fluctuations are all but
impossible. However, the timing light was showing the timing bouncing 15-20
degrees at idle and as you revved the engine up the timing mark would just
disappear at about 3000 rpm. After we were done with the troubleshooting it
was discovered that the timing light was triggering off both the leading and
trailing edges of the trigger signal at idle and as the rpm increased it
started triggering from the adjacent cylinder that it was not even connected
too! That was pretty much the last time I used a timing light. I do all my
timing statically now.
Anyone?
AL
On a P.S. to the spark plug part of this thread, i spoke to a guy called Tim from the Green Spark Plug company the other day.
Whilst he admits that he is not a technical person he did say that the problems of early fouling and intermittent running are universal in older engines these days.
Particularly those which need 'flooding' of the carbs prior to cold starting and those that run primitive oil control piston ring setups.
All his customers are getting the same thing and he gets at least five to ten calls every day with the same scenario spelled out by owners of different vehicles.
He sympathised and could offer no viable alternative but he did suggest that this has been a deteriorating situation which in his experience has only come about with changes in fuel composition over the last ten or fifteen years due to the arrival of modern lean burn engines.
On a practical note he said that you should not allow the engine to idle on choke, dont flood to start, get the engine properly hot as soon as possible, maintain it in the best condition possible and change your plugs often and this he suggested to be at every 2000 miles.
He also made a big point about never cleaning the plugs because it kills them instantly.
He didnt offer any other manufacturers products as alternatives and when asked he suggested either; wait for it............... NGK or Denso.
I think what he is describing are the positive and negative electrodes on the spark plug. Positive current is supplied to the insulated centre electrode, is attracted to ,and jumps the gap to, the negative electrode from where it is dissipated to earth. The by product of which is a big bang in the cylinder 
(hopefully at the right time - otherwise:( )
Or it doesn't and current leaks through the insulator to earth and you get a missfire
(hopefully at the right time - otherwise:( )
Or it doesn't and current leaks through the insulator to earth and you get a missfire
Insert witty comment here.......
That is of course unless you want to be really spotterish - in which case the spark actually jumps from the negative to the positive electrode. Because current flow is really negative to positive, but we all knew that, right
The bit about the timing light was interesting as well. I've seen exactly what Mr Technical described on my bike, funnily enough using a Snap On timing light. Anyone else seen it as well?
The bit about the timing light was interesting as well. I've seen exactly what Mr Technical described on my bike, funnily enough using a Snap On timing light. Anyone else seen it as well?
Insert witty comment here.......
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Ginger Bear
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I've been following this thread with interest & it seems we are all fooked! Nobody makes an 'old style' porcelain insulated plug to suit our bikes anymore. Coupled with the fact that many of our bikes are a little out of tune/tired only compounds the problem.
At least I can sit back, in the knowledge that I am not the only one suffering these problems.
I will be looking out for those NOS plugs on ebay !!!!!!!!!!!!!!!!!
At least I can sit back, in the knowledge that I am not the only one suffering these problems.
I will be looking out for those NOS plugs on ebay !!!!!!!!!!!!!!!!!
We used to clean plugs in a special plug cleaning cabinet which was basically a sand blaster. This was back in the day when you serviced your Escort van every 3000 miles.
Plugs are cheap, although I`ve had no problems with my basic points setup, I`ll change them every year.
Now where did I put all those old B8ES`s from my LC
Plugs are cheap, although I`ve had no problems with my basic points setup, I`ll change them every year.
Now where did I put all those old B8ES`s from my LC
Asphalt Cowboy
Phil Churchett award winner 2015
Phil Churchett award winner 2015
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