Topic: Can't find non-resistor plug caps--how do you run DR8EIX iridium resistor plugs?

[Holden]

I read that it's not good to run resistor plugs with resistor caps.  I have the stock caps with stock coils (non-removable wires) and the only caps I can find are NGK resistor caps.  What do you do if you upgrade to DR8EIX iridium, which only come as resistor plugs?

[TwoTired]

As a parallel.  What are the benefits of race tires on your family car?

[Bankerdanny]

As a parallel.  What are the benefits of race tires on your family car?

By which I believe he means, why would you feel the need to run Iridium plugs on a low tech bike like an old CB?

[mlinder]

Just pop in some d8ea plugs and be done with it.

[Syscrush]

By which I believe he means, why would you feel the need to run Iridium plugs on a low tech bike like an old CB?

Easier starting and a longer service interval?

[TwoTired]

By which I believe he means, why would you feel the need to run Iridium plugs on a low tech bike like an old CB?

Easier starting and a longer service interval?

Based on what science?

[Syscrush]

Based on what science?

Handley, J. R. (1986). "Increasing Applications for Iridium". Platinum Metals Review 30 (1): 12–13. LINK.
Stallforth, H.; Revell, P. A. (2000). Euromat 99. Wiley-VCH. ISBN 978-3-527-30124-9. LINK.

[mlinder]

Odd, I never had issues running the factory recommended plugs on a decently maintained SOHC4.

[Pinhead]

Back to the OP....

The factory plug caps have removable resistors. Stick a flat screwdriver inside the plug end of the caps and unscrew the stop, and replace the resistors with a bolt of the same size.

I don't know If the replacement caps have removable resistors.

In fact, unless the stock caps are cracked, there's no reason to get new ones if you either replace the resistors or run resistor plugs.

[Syscrush]

Odd, I never had issues running the factory recommended plugs on a decently maintained SOHC4.

No reason why you should - they're perfectly fine.  The iridium ones just last longer.

[Holden]

As a parallel.  What are the benefits of race tires on your family car?

My bike is running ok, but I thought it could be better with better ignition components.  I'm not sure if I want to spend Dyna/PAMCO ignition money yet.  Thought I might get a little improvement with iridium plugs, especially since the PO put in D7EA plugs, which I've read are not a good idea during the summer.  I could get D8EA plugs for about $10 or for less than $20 more, I could get DR8EIX.  If there's a real-world iridium benefit for less than $20, that's not bad.  Or I could just stick with the D7EA plugs and spend nothing. 

[Bankerdanny]

I think the limited spark generating capacity of the stock setup makes the iridium plugs of limited value. With a more robust ignition system perhaps they would be worth the premium (although I know we aren't talking hundreds of dollars here). Unless you plan to upgrade the ignition soon, I would just track down stock plugs.

[TwoTired]

Odd, I never had issues running the factory recommended plugs on a decently maintained SOHC4.

No reason why you should - they're perfectly fine.  The iridium ones just last longer.

And you have data that shows this to be true for the SOHC4?

Based on what science?

Handley, J. R. (1986). "Increasing Applications for Iridium". Platinum Metals Review 30 (1): 12–13. LINK.
Stallforth, H.; Revell, P. A. (2000). Euromat 99. Wiley-VCH. ISBN 978-3-527-30124-9. LINK.

I read the links you posted.

We do not consistently run our engines at peak high temperatures, or use far more spark gap (with the required higher voltage to enable such) where iridiums would definitely show longer survival tendencies.

If your only metric for "better" is increased lifetime, can you show that the increased cost of iridiums is offset by the increased useful life in an SOHC4?
I.E, if they cost twice as much, can you show that they will last more than 2 times longer in the SOHC4 application, with its low compression, low average temperatures, and infrequent use of high power settings?

Cheers,

[Syscrush]

No, I most certainly can't.  I'm not a sparkplug engineer or SOHC4 expert.  But I don't think it's contentious to state that in an engine that's running properly, the failure mode for sparkplugs is corrosion related to the arc across the electrodes.  And I think that there's good evidence that iridium plugs are more resistant to that corrosion.

And you can't look at just the MTBF ratio vs the cost ratio, because there are costs & hassles associated with downtime and having to do the service.  If it's $30 vs. $10 (cost ratio of 300%) and it means that the plugs are good for 5 years instead of 4 (MTBF ratio of 120%), then some would say that's good value and others would say it's not.

[TwoTired]

As a parallel.  What are the benefits of race tires on your family car?

My bike is running ok, but I thought it could be better with better ignition components.  I'm not sure if I want to spend Dyna/PAMCO ignition money yet.  Thought I might get a little improvement with iridium plugs, especially since the PO put in D7EA plugs, which I've read are not a good idea during the summer.  I could get D8EA plugs for about $10 or for less than $20 more, I could get DR8EIX.  If there's a real-world iridium benefit for less than $20, that's not bad.  Or I could just stick with the D7EA plugs and spend nothing.

It really depends on what value of "better" you are seeking.

Putting aircraft spark plugs in your car will not make it fly.  A large aerial crane, industrial helicopter, or scenic cliff edge will.  (I also saw a 1953 Studebaker with no engine fly off the end of an aircraft carrier.  It only did that once, though, before it began duty as a submersible.)

It will not, by itself, make your engine produce more power.
If you are using extra electrical power to make stupid high voltages at the spark electrodes set for very wide gap, then yes, iriduim will last longer from the vast wasted energy causing electrode erosion.  Let us know if it lasts more than twice and long, ok?

As for heat range, summer use could benefit from the colder heat range plug, if you run the air cooled engine hot and at consistently higher power settings.    Some might even use D8 for hot weather and switch back to D7 for cold weather use.  You may notice more demand for a warm up before the engine runs smoothly with D8.

Cheers,

[TwoTired]

No, I most certainly can't.  I'm not a sparkplug engineer or SOHC4 expert.  But I don't think it's contentious to state that in an engine that's running properly, the failure mode for sparkplugs is corrosion related to the arc across the electrodes.  And I think that there's good evidence that iridium plugs are more resistant to that corrosion.

Did you mean to say erosion rather than corrosion?

If so, yes electrodes erode while sparking.  They can also be reconditioned several times with a small file restoring the sharp edges and simply re-gaping them.  Clean the insulator and they fire like new (non-resistor types).


Gap erosion widens the gap, which forces the coils to make higher voltages within it's capability.  When that capability is exceeded then misfires occur, and "performance" naturally degrades.
However, you aren't going to change the 3000 mile service interval by simply changing spark plugs to iridium.  And, I don't think you can recondition iridiums either (but I haven't tried).

And you can't look at just the MTBF ratio vs the cost ratio, because there are costs & hassles associated with downtime and having to do the service.  If it's $30 vs. $10 (cost ratio of 300%) and it means that the plugs are good for 5 years instead of 4 (MTBF ratio of 120%), then some would say that's good value and others would say it's not.

Feel free to factor those other thing in if you wish.  However, I would point out that a 35 year old motorcycle, that is "maintenance free", is a bit of a myth.  If you don't want to or like to work on these old machines, why would you even want one?

Cheers,

[scw1984]

So D7EAs are more for use during the winter? Would the D8EAs be best for summer time in Texas?

[mlinder]

Yes.

[scw1984]

Gotcha, thanks for the help had the idea backwards I suppose

[TwoTired]

So D7EAs are more for use during the winter? Would the D8EAs be best for summer time in Texas?

Depends on the SOHC4 you are discussing.
For Cb750s, yes.
Not for the Cb550 though.

Cheers,

[Syscrush]

Did you mean to say erosion rather than corrosion?

Yes I did, thank you.

If so, yes electrodes erode while sparking.  They can also be reconditioned several times with a small file restoring the sharp edges and simply re-gaping them.

Only if you pull 'em out.

However, you aren't going to change the 3000 mile service interval by simply changing spark plugs to iridium.

That's interesting.  Why not?  Are you talking about the spark plug service interval specifically, or other items, too?  This is an honest question and I'm very interested in learning.

Feel free to factor those other thing in if you wish.  However, I would point out that a 35 year old motorcycle, that is "maintenance free", is a bit of a myth.

It's not a bit of a myth, it's a physical impossibility.  It's also not something that anyone mentioned anywhere in this thread.

If you don't want to or like to work on these old machines, why would you even want one?

So, the only valid reason to want a nice CB is because you enjoy gapping plugs and adjusting points?  I suppose that putting an O-ring chain on is a dumb idea too because real CB aficionados enjoy pulling off a chain and soaking it in hot wax or gear oil or whatever.  Of course, putting a better SCR-type regulator in to replace the mechanical one must be a bad idea, and similarly for going with a SLA or AGM battery.  I suppose only NOS tires made from crap 70's rubber is acceptable also.

[scw1984]

So D7EAs are more for use during the winter? Would the D8EAs be best for summer time in Texas?

Depends on the SOHC4 you are discussing.
For Cb750s, yes.
Not for the Cb550 though.

Cheers,

Yes for a 75 cb750f ss in particular

[TwoTired]

If so, yes electrodes erode while sparking.  They can also be reconditioned several times with a small file restoring the sharp edges and simply re-gaping them.

Only if you pull 'em out.

Which you have to do to clean them.

However, you aren't going to change the 3000 mile service interval by simply changing spark plugs to iridium.

That's interesting.  Why not?  Are you talking about the spark plug service interval specifically, or other items, too?  This is an honest question and I'm very interested in learning.

Seems like you haven't read the owner's manual.  See attached:
But, unless your bike is from the lean burn era/has an accelerator pump, or CV carbs, the idle is purposely set rich, which soots up the insulators on the spark plugs.  I don't care if the electrodes are iridium, if the insulator gets a conductive coating is will still fail or cause misfires.  So, spark plug cleaning at 3000 miles is still recommended, mostly because they way the bike is operated by any specific individual is unknown.  Idling in traffic, soots them, WOT throttle helps clean them. "Average" conditions require them to be cleaned at 3000 mile intervals, and the gap "adjusted if necessary".

Feel free to factor those other thing in if you wish.  However, I would point out that a 35 year old motorcycle, that is "maintenance free", is a bit of a myth.

It's not a bit of a myth, it's a physical impossibility.  It's also not something that anyone mentioned anywhere in this thread.

If you don't want to or like to work on these old machines, why would you even want one?

So, the only valid reason to want a nice CB is because you enjoy gapping plugs and adjusting points?  I suppose that putting an O-ring chain on is a dumb idea too because real CB aficionados enjoy pulling off a chain and soaking it in hot wax or gear oil or whatever.  Of course, putting a better SCR-type regulator in to replace the mechanical one must be a bad idea, and similarly for going with a SLA or AGM battery.  I suppose only NOS tires made from crap 70's rubber is acceptable also.

Nobody mentioned much of those things in prior comments either.  But, somehow we are to assume they are justification of iridium plugs?
SLA and AGM batteries have their own trade offs, which have nothing to do with iridium spark plugs.  Start another thread, if you wish.

But, since the rat hole is expanding,  Yes, it is a dumb idea to put an oring chain on a Cb550.
No one makes an SCR regulator for an SOHC4 AFAIK.  Do you know of a specific example?  They may make a Solid State Regulator, which will work ok if the mechanical one fails, but even then, it is not "better", only different.

I suppose you are going to tell us all, that newer tires will add 10MPH top speed, improve fuel economy by 20%, and add 10 years to all our life spans, just because a newer technology is involved?  (Just kidding... and to demonstrate I can put words in your mouth, too.)

Cheers,

[Syscrush]

But, unless your bike is from the lean burn era/has an accelerator pump, or CV carbs, the idle is purposely set rich, which soots up the insulators on the spark plugs.  I don't care if the electrodes are iridium, if the insulator gets a conductive coating is will still fail or cause misfires.  So, spark plug cleaning at 3000 miles is still recommended, mostly because they way the bike is operated by any specific individual is unknown.  Idling in traffic, soots them, WOT throttle helps clean them. "Average" conditions require them to be cleaned at 3000 mile intervals, and the gap "adjusted if necessary".

That's interesting, thanks for the info.  My expectation was that a properly-tuned motor shouldn't soot up the plugs, but I've not lived with a bike of this era yet.

[Skunk Stripe]

I think some people need to stop being so stuck on the manual and maybe, just maybe look at newer technology.
Iridium plugs are better than copper. It is a fact. It is a tested fact and not just by the manufacturers or spark plugs.
http://www.spark-plugs.co.uk/pages/technical/iridium_spark_plugs.htm

Due to the properties of Iridium, the spark plugs centre electrode can be made with a much smaller diameter than with platinum, Gold or gold palladium and copper/nickel types without sacrificing service life. The spark plugs potential difference is more concentrated at the tiny Iridium tip and hence less 'spark jump' voltage is required - this can be as much as 5,000 volts less than with standard plug types. Ignition is improved and less strain is placed on the ignition system. Benefits of improved ignition/combustion include better fuel economy, increased power/acceleration and especially better throttle response.

http://www.globaldenso.com/en/products/aftermarket/plug/power/features.html
http://www.automedia.com/Iridium_Spark_Plugs/pht20010101ds/1

Now, if you have higher spark, you will burn more fuel, that is pretty much guaranteed. More fuel burned means less chance of carbon build-up and thus, less cleaning.
The harder metal mean less wear and thus longer life and less concern of gaps.
The harder metal allows for a thinned electrode which therefore takes less energy to create spark. Meaning that iridium can take advantage of lower spark energies.

I know some may poo poo this because it does not meet some sort of scientific test that they were not part, yet they will not try it but continue to put it down. Thats ok, some of us will try it and so far, those that have, are happy with the results.

Of course we can all use hard rubber from the 70s because it grips just as well as rubber made today. Oh wait, no it doesn't.