Anyone try iridium plugs in their klx?
#12
07-29-2013, 10:54 PM
They used a similar concept in the old H1 500 triple, called surface discharge. It was flat instead of having the tip protrude into the cylinder. I just read where I one of the more well known knowledgeable people in the motorcycle media made a comment that they worked pretty good in his old H1, but went by the wayside without any really good reason. Apparently people didn't like them and went to regular plugs because they were familiar with them... you don't gap a surface discharge.
From my point of view all the plug does is fire the mix. The mix makes the power based on the rest of the engine tune when it burns. If the mix fires efficiently with a common plug a trick plug cannot improve on the firing and does nothing for horsepower. But if it does help the mix ignite in a more efficient way every time that's another story, it is contributing to power output. Still it maybe infinitesimal in value, only detectable in high horsepower vehicles where a 1-2% gain can be seen on a dyno.
I do agree with TNC, the iridium tips are more resistant to erosion where the corners round. A spark is an arc of electrons from an edge and usually jump much easier from a sharp edge. Champion made a similar type plug back in the early 70s, their Gold Paladium plug I believe it was. We ran them in the flat track two strokes because it was far more resistant to fouling. If you want to consider that a horsepower gain, it is when the engine continues to fire properly.
The surface discharges provided more sharp edges from which to have the spark jump. It will jump at the point of least resistance, aka the closest point to the center electrode. The Splitfires and E whatevers do the same - present more sharp edges from which the spark can jump the gap.
You want to get really complicated, check out indexing the plug to get the gap aimed toward I believe the intake valve. Drag racers were big into that, I don't know if that is still true.
Summary - only horsepower gain is if the mixture ignites in a more efficient (quicker or more thorough) fashion, from there the engine may draw a shade more power in the combustion, but maybe not. The rare metal tips are erosion resistant and will allow the plug to be run far longer.
From my point of view all the plug does is fire the mix. The mix makes the power based on the rest of the engine tune when it burns. If the mix fires efficiently with a common plug a trick plug cannot improve on the firing and does nothing for horsepower. But if it does help the mix ignite in a more efficient way every time that's another story, it is contributing to power output. Still it maybe infinitesimal in value, only detectable in high horsepower vehicles where a 1-2% gain can be seen on a dyno.
I do agree with TNC, the iridium tips are more resistant to erosion where the corners round. A spark is an arc of electrons from an edge and usually jump much easier from a sharp edge. Champion made a similar type plug back in the early 70s, their Gold Paladium plug I believe it was. We ran them in the flat track two strokes because it was far more resistant to fouling. If you want to consider that a horsepower gain, it is when the engine continues to fire properly.
The surface discharges provided more sharp edges from which to have the spark jump. It will jump at the point of least resistance, aka the closest point to the center electrode. The Splitfires and E whatevers do the same - present more sharp edges from which the spark can jump the gap.
You want to get really complicated, check out indexing the plug to get the gap aimed toward I believe the intake valve. Drag racers were big into that, I don't know if that is still true.
Summary - only horsepower gain is if the mixture ignites in a more efficient (quicker or more thorough) fashion, from there the engine may draw a shade more power in the combustion, but maybe not. The rare metal tips are erosion resistant and will allow the plug to be run far longer.
Last edited by klx678; 07-29-2013 at 10:59 PM.
#13
07-30-2013, 12:40 AM
Mark, since we're waxing nostalgic here, do you remember what it took to fire those surface spark plugs? Lots of voltage. The Kawi 500 H1's had a 50,000-60,000 volt spark if I remember correctly. They used that distributor style electronic ignition that bit you big time if you brushed up against it while running. I think they only used that for '69 and maybe into '70. Freaking arc welder.
That spark plug indexing you mention was interesting. Today's AA fuel dragsters actually use 2 plugs per cylinder to overcome the need for that. However, some engines with 1 plug and only 2 valves often can benefit from having the spark not shrouded from the incoming intake charge. Engines with 2 valves but 2 plugs per cylinder are good to go, and engines with 4 valves like our KLX have little issue with the ground strap shrouding the spark.
On all my V8 Chevy setups, I did like to use an MSD-6 box for multiple sparks along with a stouter coil. I feel it provided a small improvement in mileage and less detonation when towing.
That spark plug indexing you mention was interesting. Today's AA fuel dragsters actually use 2 plugs per cylinder to overcome the need for that. However, some engines with 1 plug and only 2 valves often can benefit from having the spark not shrouded from the incoming intake charge. Engines with 2 valves but 2 plugs per cylinder are good to go, and engines with 4 valves like our KLX have little issue with the ground strap shrouding the spark.
On all my V8 Chevy setups, I did like to use an MSD-6 box for multiple sparks along with a stouter coil. I feel it provided a small improvement in mileage and less detonation when towing.
#15
07-30-2013, 06:44 PM
These Plugs are unique spark plugs that are designed to
- increase horsepower,
- increase acceleration,
- improve throttle response,
- reduce emissions,
- improve fuel efficiency.
- increase horsepower,
- increase acceleration,
- improve throttle response,
- reduce emissions,
- improve fuel efficiency.
#16
07-30-2013, 07:32 PM
I know this has been said in a few previous posts for the most part but here we go...
Once the combustion process is started, as far as we are concerned, that's all that matters. Rare metal plugs do in fact last a lot longer because there is less transfer of metal each time an arc occurs. I know a lot of marketing ploys show multiple tip plugs firing all at once, realistically, just like water, the electrons will take the path of least resistance. Once that electrode becomes hot and resistance increases, the spark will jump to the next electrode with the least resistance. Depending on the type of ignition systems, coil on plug, magneto and so on, I've seen these plugs cause drive ability issues, check engine lights and rough idle. In my professional experience, I'm an auto tech, I always use factory plugs. If its a Toyota V6 and I pull a twin electrode plug, that's what goes back in, if its a Audi S4 and has single tip plugs then that's what goes back in. The rare metal stuff I'm all for, no issues there. My thoughts are the manufactures have such strict emissions, fuel economy and performance standards, when they design multi valve combustion chambers with over head cams and so on, they aren't going to leave such performance gains on the table through a simple spark plug. I wonder how many times people have felt gains but it was because the old plug was marginal to begin with? Maybe it was old, maybe had carbon tracking on it, maybe the gap was so big it from being old that the spark duration was to short to promote a good flame front. I suppose I'm just thinking aloud but that's just my 2 cents.
Once the combustion process is started, as far as we are concerned, that's all that matters. Rare metal plugs do in fact last a lot longer because there is less transfer of metal each time an arc occurs. I know a lot of marketing ploys show multiple tip plugs firing all at once, realistically, just like water, the electrons will take the path of least resistance. Once that electrode becomes hot and resistance increases, the spark will jump to the next electrode with the least resistance. Depending on the type of ignition systems, coil on plug, magneto and so on, I've seen these plugs cause drive ability issues, check engine lights and rough idle. In my professional experience, I'm an auto tech, I always use factory plugs. If its a Toyota V6 and I pull a twin electrode plug, that's what goes back in, if its a Audi S4 and has single tip plugs then that's what goes back in. The rare metal stuff I'm all for, no issues there. My thoughts are the manufactures have such strict emissions, fuel economy and performance standards, when they design multi valve combustion chambers with over head cams and so on, they aren't going to leave such performance gains on the table through a simple spark plug. I wonder how many times people have felt gains but it was because the old plug was marginal to begin with? Maybe it was old, maybe had carbon tracking on it, maybe the gap was so big it from being old that the spark duration was to short to promote a good flame front. I suppose I'm just thinking aloud but that's just my 2 cents.
#18
07-31-2013, 01:01 AM
Mark, since we're waxing nostalgic here, do you remember what it took to fire those surface spark plugs? Lots of voltage. The Kawi 500 H1's had a 50,000-60,000 volt spark if I remember correctly. They used that distributor style electronic ignition that bit you big time if you brushed up against it while running. I think they only used that for '69 and maybe into '70. Freaking arc welder.
That spark plug indexing you mention was interesting. Today's AA fuel dragsters actually use 2 plugs per cylinder to overcome the need for that. However, some engines with 1 plug and only 2 valves often can benefit from having the spark not shrouded from the incoming intake charge. Engines with 2 valves but 2 plugs per cylinder are good to go, and engines with 4 valves like our KLX have little issue with the ground strap shrouding the spark.
On all my V8 Chevy setups, I did like to use an MSD-6 box for multiple sparks along with a stouter coil. I feel it provided a small improvement in mileage and less detonation when towing.
That spark plug indexing you mention was interesting. Today's AA fuel dragsters actually use 2 plugs per cylinder to overcome the need for that. However, some engines with 1 plug and only 2 valves often can benefit from having the spark not shrouded from the incoming intake charge. Engines with 2 valves but 2 plugs per cylinder are good to go, and engines with 4 valves like our KLX have little issue with the ground strap shrouding the spark.
On all my V8 Chevy setups, I did like to use an MSD-6 box for multiple sparks along with a stouter coil. I feel it provided a small improvement in mileage and less detonation when towing.
When compared to a standard K-Mart coil for like $5 the average motorcycle coil looked like a candle versus a 200 watt incandescent bulb. In the test, which was run with a simple movable electrode set up, a K-Mart coil could jump something like .078" or more, I forget the specifics, versus around .030" with a bike coil. In the actual turbulent cylinder the gap for the motorcycle coils was .028" at the widest and the K-Mart coil was instantly opened up to .040" with no problem - no fouling, no misfire.
So the trick was to get an automotive coil, condensor, and ballast resistor to wire up a new ignition for each cylinder on those RD400s and 350s along with others that ran single lead coils. I did my old MotoGuzzi 850 with a set of Ford coils. The difference was quite amazing. It started easier and had no miss or stumble at the lower rpm range. No magic plugs, but probably the Champion Gold Palladium plugs might have helped a bit. The hot coils were the trick though.
The twin lead coils that fired two plugs at once were just as pathetic, but it wasn't as simple to swap out the ignition.
Of course now all of that has been eclipsed by electronic ignitions that also allow the wider gaps to have a bigger spark to ignite the mix more efficiently.
Of couse if the stock plugs work efficiently, effectively all the trick plugs in the world won't improve on that no matter how much hype there is on them.
#19
07-31-2013, 02:04 AM
Opening up the spark plug gap works for making a higher kV spark with shorter duration. When the magnetic field collapses in the coil, the secondary circuit will have to build more before it can fire the wider gap on the plug. In a round about way I'm definitely agreeing with your statement of using a better coil with a larger gap. That for sure can fire much better then a fancy plug alone.
I know this is irrelevant to our bikes but if anyone is wondering...after the plug fires and the coil prepares for its next cycle, an inductive kick back happens and some modern ignition systems look for that "kick" as a confirmation of a spark event happening. Timing and dwell controlled by a module can be effected by this event SOOOO that's why putting the incorrect plugs or not using the proper gap can give you problems. Wrong plugs will mess up the firing kV and duration and it screws with the management portion of the system.
I know this is irrelevant to our bikes but if anyone is wondering...after the plug fires and the coil prepares for its next cycle, an inductive kick back happens and some modern ignition systems look for that "kick" as a confirmation of a spark event happening. Timing and dwell controlled by a module can be effected by this event SOOOO that's why putting the incorrect plugs or not using the proper gap can give you problems. Wrong plugs will mess up the firing kV and duration and it screws with the management portion of the system.
#20
07-31-2013, 03:06 AM
I'm really going to date myself now. There was one definite trick to unshroud the spark in a point ignition engine back in the 70s. Gordon Jennings did quite a write up and test on swapping out to hotter coils.
When compared to a standard K-Mart coil for like $5 the average motorcycle coil looked like a candle versus a 200 watt incandescent bulb. In the test, which was run with a simple movable electrode set up, a K-Mart coil could jump something like .078" or more, I forget the specifics, versus around .030" with a bike coil. In the actual turbulent cylinder the gap for the motorcycle coils was .028" at the widest and the K-Mart coil was instantly opened up to .040" with no problem - no fouling, no misfire.
So the trick was to get an automotive coil, condensor, and ballast resistor to wire up a new ignition for each cylinder on those RD400s and 350s along with others that ran single lead coils. I did my old MotoGuzzi 850 with a set of Ford coils. The difference was quite amazing. It started easier and had no miss or stumble at the lower rpm range. No magic plugs, but probably the Champion Gold Palladium plugs might have helped a bit. The hot coils were the trick though.
The twin lead coils that fired two plugs at once were just as pathetic, but it wasn't as simple to swap out the ignition.
Of course now all of that has been eclipsed by electronic ignitions that also allow the wider gaps to have a bigger spark to ignite the mix more efficiently.
Of couse if the stock plugs work efficiently, effectively all the trick plugs in the world won't improve on that no matter how much hype there is on them.
When compared to a standard K-Mart coil for like $5 the average motorcycle coil looked like a candle versus a 200 watt incandescent bulb. In the test, which was run with a simple movable electrode set up, a K-Mart coil could jump something like .078" or more, I forget the specifics, versus around .030" with a bike coil. In the actual turbulent cylinder the gap for the motorcycle coils was .028" at the widest and the K-Mart coil was instantly opened up to .040" with no problem - no fouling, no misfire.
So the trick was to get an automotive coil, condensor, and ballast resistor to wire up a new ignition for each cylinder on those RD400s and 350s along with others that ran single lead coils. I did my old MotoGuzzi 850 with a set of Ford coils. The difference was quite amazing. It started easier and had no miss or stumble at the lower rpm range. No magic plugs, but probably the Champion Gold Palladium plugs might have helped a bit. The hot coils were the trick though.
The twin lead coils that fired two plugs at once were just as pathetic, but it wasn't as simple to swap out the ignition.
Of course now all of that has been eclipsed by electronic ignitions that also allow the wider gaps to have a bigger spark to ignite the mix more efficiently.
Of couse if the stock plugs work efficiently, effectively all the trick plugs in the world won't improve on that no matter how much hype there is on them.
Me and another guy in the shop adapted 4 separate automotive coils to our '73 Z1-900 Kawasakis back in the day. We used a ballast resistor from JC Whitney to keep from burning up the points. The system was awesome. I set my plug gap at .055". Plug life was great, and mileage improved dramatically. Those dual-lead OEM coils were junk. Comparing them to candles gives candles a bad name.
OK Mark...have we taken this thread far enough afield yet? If not I have a story about a wiener dog, a rabbi, a democrat, and a broke down Harley.