Iridium Plugs

[copemech]

Never understand this keeping the same plug for years thing.

Regular changing of this cheap item keeps the spark spot on and the bike running sweet. just like a clean carb and filter for sure?

I am not neccessarily cheap, just pragmatic. And if it ain't broke, well? Oh yes, it would be out at the first sign of problems, but it just has not been the case. Not unlike Jon, it is somewhat interisting to see just what these things will do.

Of course, over time one learns to help prevent fouling by getting some heat in the motor, giving them a good run and revving to keep the motor cleaned out which helps prevent these issues on any plug. Those that do not, will not!

I could ramble on about the materials and specs, but basically within the NGK range of standard ES, platinum VX and irridium IEX range the premium materials have better electrical properties and the smaller electrodes offer less "shielding" to the mixture they are bound to ignite. In other words, the more massive electrodes actually act as a shield against the flow of the mixture and the spark wanders on the broad surfaces as compared to the smaller and more pinpoint (and open to the mix) electrodes.

I have never considered electrode wear to be an issue, under proper conditions they could well outlast the motor!

Running the gap! Well that is another story and theory in itself! All I will tell you is that your average motorcycle ignition has no excess of electrical power to run things, which is why many mfg recommendations are limited to 0.5 gap settings to run reliably.

Taking advantage of the better electrical properties of the modern plugs may let you open that up a bit, which simply provides better spark and ignition. If you can reliably open up that 0.5 gap to say 0.6, what is your percentage difference in flamefront propagation?

Looking up, 20%, looking down,maybe 15%. If the ignition system will support the added gap, the motor will run cleaner off the bottom and start easier. If it will not, it may cause other problems such as hard starting and poor response under high load conditions.

[jse]

I am not neccessarily cheap, just pragmatic. And if it ain't broke, well? Oh yes, it would be out at the first sign of problems, but it just has not been the case. Not unlike Jon, it is somewhat interisting to see just what these things will do.

Of course, over time one learns to help prevent fouling by getting some heat in the motor, giving them a good run and revving to keep the motor cleaned out which helps prevent these issues on any plug. Those that do not, will not!

I could ramble on about the materials and specs, but basically within the NGK range of standard ES, platinum VX and irridium IEX range the premium materials have better electrical properties and the smaller electrodes offer less "shielding" to the mixture they are bound to ignite. In other words, the more massive electrodes actually act as a shield against the flow of the mixture and the spark wanders on the broad surfaces as compared to the smaller and more pinpoint (and open to the mix) electrodes.

I have never considered electrode wear to be an issue, under proper conditions they could well outlast the motor!

Running the gap! Well that is another story and theory in itself! All I will tell you is that your average motorcycle ignition has no excess of electrical power to run things, which is why many mfg recommendations are limited to 0.5 gap settings to run reliably.

Taking advantage of the better electrical properties of the modern plugs may let you open that up a bit, which simply provides better spark and ignition. If you can reliably open up that 0.5 gap to say 0.6, what is your percentage difference in flamefront propagation?

Looking up, 20%, looking down,maybe 15%. If the ignition system will support the added gap, the motor will run cleaner off the bottom and start easier. If it will not, it may cause other problems such as hard starting and poor response under high load conditions.

Mark,

I haven't tried the extended gap as yet, wanting to keep the variables down while I'm "testing" the EIX, but it rated as a "wide gap" plug. The marking is "BPR5EIX-11" and the "-11" after the spec.'s is for an installed gap of 1.1mm or .044".

Jon,

"If it ain't broke, let's mess with it some more!"

[stork955]

Gday all,

As Copemech says, be careful opening up plug gaps in bikes, especially magneto ones like ours, they don't have great reserves of "grunt" like a battery/coil system does. Modern Battery/Coil ones like in your car can successfully hit 50K plus volts at a very high current (7 amps or more). This is to fire the very lean mixtures (15.1+) required by road cars. Most cars these days in fact use 1 coil per cylinder to help accommodate this.On the bikes however the system is limited in current and voltage by the source coil which makes relatively low output to drive all the ignition. Its like fitting a resistor plug cap to early systems, this can take the CDI out as a result of drawing more current than the system can safely handle. A wide plug gap has the same effect, the voltage required to ionise the gap and commence spark increases massively with wider gaps. Yes, its true that a wide gap can sometimes mask off a misfire or other symptom but this is temporary as you may well be driving your gear into extinction. Also, keep in mind that spark plugs rarely fail on their own (I know this as I have been fitting them for nearly 30 years now, for a living by the way) Problems are generally caused by some other issue like overly rich mixtures (Carb issues, air cleaner issues) and oil fouling (in 4 strokes mainly, poor oil control - rings, valve guides/stem seals) so if your plugs are failing on a daily basis, don't blame the plug, look for the actual cause! (Think about your car - do you change the plug every time you drive it? If you do you are looking for a problem somewhere as most modern cars and road bikes get 40 000km plus from a spark plug. Considerably more life than we expect from a relatively limited-use trials bike). All plugs are pretty much good these days, of course I have my favourites but that is based on 30 years worth of daily experience seeing what works well and what doesn't. Given that all else is OK with your engine any "correct" spark plug will do the trick for you.

Hope that all makes sense,

Cheers,

Stork

[b40rt]

Gday all,

As Copemech says, be careful opening up plug gaps in bikes, especially magneto ones like ours, they don't have great reserves of "grunt" like a battery/coil system does. Modern Battery/Coil ones like in your car can successfully hit 50K plus volts at a very high current (7 amps or more). This is to fire the very lean mixtures (15.1+) required by road cars. Most cars these days in fact use 1 coil per cylinder to help accommodate this.On the bikes however the system is limited in current and voltage by the source coil which makes relatively low output to drive all the ignition. Its like fitting a resistor plug cap to early systems, this can take the CDI out as a result of drawing more current than the system can safely handle. A wide plug gap has the same effect, the voltage required to ionise the gap and commence spark increases massively with wider gaps. Yes, its true that a wide gap can sometimes mask off a misfire or other symptom but this is temporary as you may well be driving your gear into extinction. Also, keep in mind that spark plugs rarely fail on their own (I know this as I have been fitting them for nearly 30 years now, for a living by the way) Problems are generally caused by some other issue like overly rich mixtures (Carb issues, air cleaner issues) and oil fouling (in 4 strokes mainly, poor oil control - rings, valve guides/stem seals) so if your plugs are failing on a daily basis, don't blame the plug, look for the actual cause! (Think about your car - do you change the plug every time you drive it? If you do you are looking for a problem somewhere as most modern cars and road bikes get 40 000km plus from a spark plug. Considerably more life than we expect from a relatively limited-use trials bike). All plugs are pretty much good these days, of course I have my favourites but that is based on 30 years worth of daily experience seeing what works well and what doesn't. Given that all else is OK with your engine any "correct" spark plug will do the trick for you.

Hope that all makes sense,

Cheers,

Stork

Any way of telling if its a rich mixture, or burning oil, thats killing plugs ?

[jse]

Any way of telling if its a rich mixture, or burning oil, thats killing plugs ?

Stork brings up a lot of valid points and I agree that, if everything else is in good shape, any "correct" plug will perform well. I also think that, with the marginal nature of most bike CDI systems that entended gaps have a very limited return in performance. I've generally found that the early systems, like the MotoPlat, do better with a .5mm plug gap and the newer types work well with .6mm.

Although, to do a proper plug check, you'll need to know under what conditions the engine was operating at the time it was shut down, the oil fouled plug will tend to have a glossier finish to the deposits and the over-rich mixture may have a flatter finish and darker color, but as I said, engine operating condition at time of shutdown has an effect and sometimes it's difficult to tell the oil from the fuel fouling.

Different fuels will have a different color deposit to the porcelian, some race fuels will have a gunmetal grey and some will have a golden tan to them. Plug condition is an indicator and can give you a direction to go, but other tests, like compression pressure or ring end-gap are helpful too. Sometimes it's not really the plug's fault as poor ground/connections in the CDI or a malfunctioning plug cap/wire can be the culprit.

Jon

[copemech]

Stork does make good points! And as he well knows, the best plug in most vehicles is the one that WORKS, and has been proven to work well! USUALLY the one that is recommended by the manufacturer or its close varient by the same plug manufacturer. Even at that, you are not guaranteed good results! Change brands or whatever, you then become their #1 test pilot! Trust me, I have found out the hard way, which is not the good way.

This nut tends not to stray far from the tree! Yet there are other things I can tell, such as the generally accepted fact that the premium fine wire plugs used in piston aircraft are known for paying for themselves in increased fuel efficiency over time due to better ignition properties. The simple ability to ignite the fuel in the hole is better! If you think this has no import, then take your average piston aircraft, running on dual mags and dual plugs for redundancy, then cut off one mag(and set of plugs), there may be a rpm drop of as much as 5%! Those special plugs for aircraft may cost $50 each! Multiply by 2 per cyl! They get expensive! Yet this is just an example of better efficiency as compared to a massive electrode standard plug.

Storks other point in relation to the car. Well, if you just started it up and went from section to section while shutting down and restarting every time, it would likely fowl plugs too! Fuel or oil would make little difference here if you never really got out and drove the friggin car! As these things require a bit of normal running and cleaning out from time to time. Seems some negate that fact and just putt about, shut down, putt, shut putt,shut! If you never evem attempt to see if your bike will even achieve maximum RPM, then it may well not when you need it most!

Blow some soot out of it! This is basic plug maintenance!

Edited March 26, 2009 by copemech

[b40rt]

Stork brings up a lot of valid points and I agree that, if everything else is in good shape, any "correct" plug will perform well. I also think that, with the marginal nature of most bike CDI systems that entended gaps have a very limited return in performance. I've generally found that the early systems, like the MotoPlat, do better with a .5mm plug gap and the newer types work well with .6mm.

Although, to do a proper plug check, you'll need to know under what conditions the engine was operating at the time it was shut down, the oil fouled plug will tend to have a glossier finish to the deposits and the over-rich mixture may have a flatter finish and darker color, but as I said, engine operating condition at time of shutdown has an effect and sometimes it's difficult to tell the oil from the fuel fouling.

Different fuels will have a different color deposit to the porcelian, some race fuels will have a gunmetal grey and some will have a golden tan to them. Plug condition is an indicator and can give you a direction to go, but other tests, like compression pressure or ring end-gap are helpful too. Sometimes it's not really the plug's fault as poor ground/connections in the CDI or a malfunctioning plug cap/wire can be the culprit.

Jon

Thanks for the info. I think its a combination of both as I use different carbs for events (Amal pre 65 Scottish, Kiehn rest of time) Definatly uses fewer plugs on the Kiehn than Amal, but still getting the jetting right so it might improve. I can feel when the plug is going "off" about 5 mins before it expires. I use a foam air filter and getting the same amount of oil through it consistently probably doesnt help.

Ross

Edited March 26, 2009 by B40RT

[jse]

Thanks for the info. I think its a combination of both as I use different carbs for events (Amal pre 65 Scottish, Kiehn rest of time) Definatly uses fewer plugs on the Kiehn than Amal, but still getting the jetting right so it might improve. I can feel when the plug is going "off" about 5 mins before it expires. I use a foam air filter and getting the same amount of oil through it consistently probably doesnt help.

Ross

The red or green color in the filter oil is a dye to tell you if the whole filter is saturated. You can use a large plastic bag to knead the filter in the oil (don't skimp on oil, you can pour the excess back in the bottle when you use a bag), but the key is to blot out all the excess filter oil with paper towels afterward. Knead the filter in the towels until there are no spotty deposits of oil (and the color is consistant throughout) and you're set. Be sure to squish the filter carefully with your fingers when kneading it and never pull on it or that may weaken the seams.

As to the Iridium plugs, I'm looking for one for my friend's Saracen, which takes a 3/8th" thread depth so I think it's a "BPR5SIX" (a 1/2" depth would be a "BPR5HIX".

I like the EIX plug as it seems to allow a little "wiggle room" in jetting. I went to the Ute Cup in Colorado last year (same plug still in the bike now) and dropped the main jet size 2 down, but the altitude ranges over several thousand feet in the loop, along with huge changes in temperature and humidity but the bike ran spot on all the time and didn't miss a beat even under the severe conditions that altered jetting requirements.

Jon

Edited March 27, 2009 by JSE

[stork955]

Copemech writes-

:::::::::::::::::::::::::::::::::::::::

Storks other point in relation to the car. Well, if you just started it up and went from section to section while shutting down and restarting every time, it would likely fowl plugs too! Fuel or oil would make little difference here if you never really got out and drove the friggin car! As these things require a bit of normal running and cleaning out from time to time. Seems some negate that fact and just putt about, shut down, putt, shut putt,shut! If you never evem attempt to see if your bike will even achieve maximum RPM, then it may well not when you need it most!

Blow some soot out of it! This is basic plug maintenance!

:::::::::::::::::::::::::::::::::::::::

(Sorry I couldn't work out the quote box thingy)

Good point! Stop/Start and cold running is an issue with our bikes. We see the big boys "cleaning" their 2 stroke bikes out on the DVD's all the time, and I do it myself. Not that it helps me ride any better... It is natural for 2 strokes to carbon up as they constantly burn their own oil so that can help things, give it a good ride to get it hot and a blast and see what happens afterwards. It might just stop any issues experienced. Certainly I have no trouble with any of my bikes.

Cheers,

Stork

[b40rt]

The red or green color in the filter oil is a dye to tell you if the whole filter is saturated. You can use a large plastic big to knead the filter in the oil (don't skimp on oil, you can pour the excess back in the bottle when you use a bag), but the key is to blot out all the excess filter oil with paper towels afterward. Knead the filter in the towels until there are no spotty deposits of oil (and the color is consistant throughout) and you're set. Be sure to squish the filter carefully with your fingers when kneading it and never pull on it or that may weaken the seams.

As to the Iridium plugs, I'm looking for one for my friend's Saracen, which takes a 3/8th" thread depth so I think it's a "BPR5SIX" (a 1/2" depth would be a "BPR5HIX".

I like the EIX plug as it seems to allow a little "wiggle room" in jetting. I went to the Ute Cup in Colorado last year (same plug still in the bike now) and dropped the main jet size 2 down, but the altitude ranges over several thousand feet in the loop, along with huge changes in temperature and humidity but the bike ran spot on all the time and didn't miss a beat even under the severe conditions that altered jetting requirements.

Jon

I will have to be more through when oiling the air filter to rule this out of the equasion. Reading Stork955's point about "clearing 2 strokes out before a section" my bike cant be burning any more oil than a 2stroke so I think I should be concentrating on carburation first.

Ross