Yaw Ignition Article
12-23-03, 10:06 PM
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Yaw Ignition Article
A long time ago someone here posted a link to an article at Yaw's old internet page describing different spark plugs and the results he gained from using them.
I just checked the link again and it is gone now. I checked his new site and it is not included in his technical articles nor can I bring it up by just adding the ignition.html to the end of his address like at the old site.
Does anyone have a copy of that article laying around?
I just checked the link again and it is gone now. I checked his new site and it is not included in his technical articles nor can I bring it up by just adding the ignition.html to the end of his address like at the old site.
Does anyone have a copy of that article laying around?
12-24-03, 07:51 AM
#3
I read your email
This one?
Ignition System
The ignition system on a rotary, or any other engine for that matter, cannot be ignored when performing horsepower mods. If you are still using a distributor, you are losing horsepower. Period! If you have a second or third generation RX-7, you already have an excellent ignition system. These systems are direct fire, with a "wasted spark" setup on the leading Ignition. Direct fire ignition systems deliver a hotter spark, and the timing is much more stable. As an added benefit, you don't have to change your cap and rotor every other week to keep you car running well.
These direct fire systems are very good, but still leave room for improvement. The biggest problem is that the bean counters at Mazda, and all other auto manufacturers have more to do with the finished product than the engineers do. In other words, make it as cheap as possible. These distributorless systems are known as an inductive discharge ignition. Inductive discharge ignitions suffer from poor spark at high rpm, and this is aggravated by the wasted spark arrangement on the leading ignition which fires twice per revolution. Without going into a lot of detail, the simplest explanation is that the coils do not have enough time to build a strong magnetic field at high rpm, and so the spark continues to weaken as the engine speed increases. The bean counters don't give a ****, because this system works great at low speed, and gives good mileage and driveability. This is the number one priority, even in a sports car.
Buy an MSD 6A
Luckily, this is easy to fix. Buy an MSD. In case you didn't hear me the first time, Buy an MSD! Every vehicle on the planet should have one, even your grandmothers grocery getter. The MSD is a capacitive discharge system, which does not loose spark intensity at high rpm. Capacitive discharge systems deliver a very strong, but short duration spark. To overcome this, the MSD delivers multiple sparks over twenty degrees of eccentric shaft duration. This amounts to as many as six sparks at idle, and as little as two at high rpm, but no matter how many times it fires, the spark always lasts for a full twenty degrees. This is the best of both worlds, a high intensity, long duration spark. Just about every racecar on the planet has one, and you should too.
I have installed many MSD's, and the results were always more power, better driveability, and better gas mileage. A second or third gen. will require three boxes for the entire ignition system. This is quite expensive. You can make a large improvement by simply buying one box for the leading, and the results will be even better if you replace the stock dual coil with two MSD Blaster coils. Simply run both coils from the same MSD box. The ultimate setup is of course three MSD 6A's, and four blaster coils, but this will set you back about $700, and you probably will not fit all of this under the hood.
Well, that's about it for the second and third gen RX's. I am currently testing spark plugs, and I will post the results in the future. There is more power here than I thought, especially after I got away from the conventional NGK's. As soon as I have some dyno results, they will be on the page.
Distributors Suck
Now for the first generation. Distributors suck! Distributors require that the charge jump a .075" gap from the rotor to the cap before it can even fire the .055" gap of the spark plug. The gap in the distributor cap is easier to fire than the spark plug gap, because there is much less pressure, but it is still a really shitty way to make fire. Luckily it is relatively easy to convert the leading ignition to direct fire. I finally got around to doing this on my 13B, and then I was mad at myself for not doing it sooner.
Before the conversion, I was using an MSD 6A, with an Accele super coil. This is a lot of juice, so I was really surprised at the improvement after converting to direct fire. I called MSD to be sure that their box would fire two coils, and their tech guy said "Hell, it would probably fire a whole row of coils." I set it up with two stock coils for the leading ignition and was stunned at the results. The engine made more power everywhere in the powerband, and the driveabilty improved dramatically. I will never again run an MSD through the distributor.
Here's how it works. All you need is an MSD 6A, and an extra coil. Two for the leading, and one for the trailing. Trigger the MSD with the magnetic trigger inside of the distributor.Do not try to trigger the MSD with the ignitor! The ignitor output is very "dirty", and does not give the MSD a clean signal to work with. Simply cut the green, and red wires that go from the leading magnetic trigger to the ignitor. The leading ignitor is the one facing the front of the vehicle. Connect the green wire from the trigger, to the purple wire of the MSD, and connect the red wire from the trigger, to the green wire of the MSD. Wire power, ground, and ignition as per MSD's instructions. The orange, and black 16ga. wires from the MSD go to the coil. In this case, make two jumpers and connect both coils to these wires. Make sure that the polarity is correct. The stock coils are labeled positive and negative. The orange wire goes to positive, the black wire goes to negative. Do not screw this up! The same goes for the magnetic trigger in the distributor. If you wire the trigger backwards, the timing will be advanced by approximately thirty degrees. Now simply run a plug wire from each coil to a leading spark plug. It doesn't matter which one, because they will both fire at the same time. Leave the trailing ignition just as it is.
This is referred to as a "wasted spark" system because eack rotor recieves an additional spark during the exhaust phase. On a rotary, this extra spark is actually beneficial, because it fires at the trailing end of the chamber which is where most of the unburned fuel is concentrated. Igniting this fuel will not make more power, but it will clean up the emissions slightly. DO NOT try this setup on the trailing ignition. Because of the different spark plug location you will ignite the incoming mixture from the next stroke. At best, you will lose power, at worst, you will break apex seals. If you have any questions about this, feel free to send a message. This is a simple wiring job, and the results are amazing. This is cheap power, and the improvement in gas mileage will probably pay for the MSD in a years time. I have not tried this with upgraded coils, but when I do, I will let you know if there is further improvement. I am only sorry that I didn't try this on the dyno so that I could measure the improvement in horsepower. Next time I have a 12A on the dyno, I might do a comparison, and post the results.<p>
Spark Plugs
I have been doing some spark plug testing recently, and have been surprised at the results. I have been doing this testing on my daily driver, a bridge ported 13B. Almost everything starts here, and then makes its way to the dyno if the results seem worthwhile. In this engine, I have had the best luck with the Autolite 2526. You know, those cheap nasty plugs that they try to sell you at the discount auto parts store. These plugs have only one ground strap, instead of four like the NGK, or ND plugs. If you look at one of these, it makes sense that they would produce more power because the spark is much less shrouded. This will allow the flame to travel more easily from the face of the plug to the combustion chamber which is a big problem with the rotary anyway.
I should mention that these plugs do not work well without an MSD. It seems that the gap is to great for the stock ignition system to fire consistently. I found that with an MSD on the leading, and stock ignitor on the trailing, that these worked better in the trailing position than the NGK's. However,a friend with a completely stock ignition found that they just plain didn't work as well as the NGK. Until I have a chance to check this out myself, I will not reccommend them for stock ignitions.
After trying every plug made for the rotary, and finding that the cheap Autolite worked best, I decided to call Autolite and find out why. This plug was only available in one heat range, and so I at least wanted to know if they had something similar in a hotter and cooler plug. I was very lucky to contact Don Ward who is an engineer in charge of their motorsports program. I explained all of this to Don, and he agreed that the spark was less shrouded, and this is why they made more power. He also expalined that a resistor plug was prone to misfire above about 7000 rpm. I didn't know this, and so I expalined to him that I was stupid, and asked what he recommended.
Autolite makes an extended tip non resistor plug that is available in four heat ranges, and costs a whopping 99 cents. The extended tip helps to further unshroud the spark, and also moves the electrode .060" closer to the rotor housing surface. This is a conventional style plug, with the ground strap reaching all of the way over the top of the electrode. I ground this off to convert it to a side fire, set the gap to .055", and headed out to the truck to install them. Oops, they didn't fit! This plug has a very short shell, and so the socket needs to extend not only beyond the boss on the rotor housing, but beyond the flat surface as well. Have die grinder will travel! Twenty minutes later, I had the plugs installed in the leading position and Holy ****! I never thought that a spark plug could make such a difference. Power improved throughout the rpm range, and it was much smoother at high rpm.
These will definetely be tested on the dyno, and I promise to post the results so that you can see it for yourself. The next step is to replace the sealing washer with a thinner piece to get the spark an additional .040" closer to the combustion chamber. I will try this on the street engine as well, and these plugs will be comparison tested on the E-Production engine which will be on the dyno the last week of October.
Spark Plug Update 11/3
Well, I recieved some new plugs from Autolite. This is a plug that was developed for Nascar Winston Cup racing on the superpeedways. It just happens to fit the rotaries. It is a 5/8 hex, and so it will fit without modifications. The plugs that I recieved (part number 3910) are prototype pieces, and I am still not sure if they will be production pieces.
These plugs were designed to withstand hundreds of full throttle laps. They are an extended tip design, but they look very much like the BUR-EQ's. They have four ground straps, that are part of the shell, rather than being welded to the shell. So, to get down to details, they extend so far into the rotor housing that the center electrode is only .030" from the apex seal. If you were to install these without the sealing washers, they would protrude into the chamber and munch your apex seals. For the sake of comparison, they are nearly .100" longer than a stock plug.
So how do they perform? Not as well as the modified 99 cent plugs. They do however perform better than the stock plugs, and they will withstand just about anything that a race motor could do to them. But this is not the end of the story. I milled off three of the ground straps, and reinstalled them. Once again unshrouding the spark paid off. The difference was amazing! They work GREAT! So far better than anything I have tried. Autolite says that these plugs will be expensive. Probably in the 5 to 8 dollar range, if they are even produced at all. If these are not produced, it will not have been a waste of time, because they helped illustrate the importance of unshrouding the spark.
As an alternative, I am searching the manufacturers catalogs for a non resistor, 5/8" hex, extended tip plug that will reach as far into the housing as these do. If I can find something in the appropriate heat range, it should work every bit as well, as the testing seems to indicate that there are only two important factors. 1. Getting the spark as close as possible to the chamber. 2. Keeping the spark as unshrouded as possible. If I can find something with a 5/8" hex, they will fit without grinding, or investing in a $50 spark plug socket.
ANOTHER Spark Plug Update 12/4
Well I finally found what I was looking for. Champion makes an extended tip non resistor plug with a 5/8" hex. It is available in four heat ranges. These plugs have the same configuration and dimensions as the Autolite 51's. So far I have been very disappointed with the life span of the Autolites. I was reminded by a friend that at 99 cents a piece it doesn't really matter, but there has got to be something that works, and lasts longer. The Champion plugs cost about $2.50 each, and the part numbers are C57YC, C59YC, C61YC, and C63YC. The heat range is equivalent to an NGK 7, 8, 9, and 10 respectively. They do require trimming of the ground strap just like the Autolites, and after closer inspection I realized that after trimming they do fit in the trailing position. I have not been driving my truck for the last month, so I cannot yet say how the power is, but being the same configuration as the Autolites I would imagine that they work as well. As for life expectancy, I don't know that yet either. So why am I telling you this? So that you will try them yourself, and give me some feedback. I will compare these to all the others on the dyno, and post the results, but this could be a month or more away.
I will eventually figure out what works best, and how long they last compared to the stock plugs, but I do have to pay the bills. In the meantime, I would really appreciate feedback from any of you who wish to experiment with these plugs. When I finally decide on a particular plug I will post the dyno results, so that you can see the results for yourself. When this is all finalized you will all be able to go a little bit faster for pocket change.
ANOTHER Spark Plug Update 6-22
OK, here we go again. As I mentioned before, the Autolite didn't last long. The Champions were even worse, and turned out to be quite fragile. I finally scrounged an NGK Sportline Catalog from a local motorcycle shop, and guess what I found. A 14mm., .750 reach, extended tip plug. BP-ES Pay dirt! Same design and dimensions as the Autolite and Champion extended tip plug. After performing the same modifications I installed them, and beat them to death. They are very tough. Just to be sure, I installed a BP7ES in the leading position which is a bit hot for an extended tip plug. I have driven around with these 7's installed for nearly a month now, and even gave them the torture test by running 90mph on the freeway for several miles. This is normally no big deal, but since the plug is too hot for this application it really put them to the test. After this I examined the ceramic with a magnifying glass, and could see no signs of cracking. The performance is the same as the other extended tip plugs, but they are much more durable. They are available at most motorcycle shops in two different heat ranges. BP7ES, and BP8ES. A BP9ES is also available, but the local shops do not stock it. They can be ordered however. The only downside is that they are a 13/16 short shell plug, and you will need a Racing Beat spark plug socket to install them. NGK also makes a racing version of this plug available in heat ranges 7,8,9, and 10 They are a 5/8 hex, so no special socket is required. The part number is R5400-heat range number. They have a fine wire gold palladium center electrode, which will reduce the voltage required to jump the gap. This may be helpful if they are used with a distributor, and stock ignitors. These are "race" plugs, and are quite pricey.
Do not forget that these plugs must be converted to side fire configuration or they will protrude into the combustion chamber and break your apex seals. I will probably purchase a case of each, and cut the ground straps on the mill. I do not yet know what the pricing will be.
Next months technical article will discuss the ignition system, and further recommendations will be made at that point.
I hope that this section of my webpage has been beneficial. After the dyno testing, I will finish this section, and polish it up a bit so it doesn't sound like the mad ramblings of someone who has nothing better to do than change spark plugs, and race around the neighborhood. For now, please excuse the typos and grammatical errors on this page.
Ignition System
The ignition system on a rotary, or any other engine for that matter, cannot be ignored when performing horsepower mods. If you are still using a distributor, you are losing horsepower. Period! If you have a second or third generation RX-7, you already have an excellent ignition system. These systems are direct fire, with a "wasted spark" setup on the leading Ignition. Direct fire ignition systems deliver a hotter spark, and the timing is much more stable. As an added benefit, you don't have to change your cap and rotor every other week to keep you car running well.
These direct fire systems are very good, but still leave room for improvement. The biggest problem is that the bean counters at Mazda, and all other auto manufacturers have more to do with the finished product than the engineers do. In other words, make it as cheap as possible. These distributorless systems are known as an inductive discharge ignition. Inductive discharge ignitions suffer from poor spark at high rpm, and this is aggravated by the wasted spark arrangement on the leading ignition which fires twice per revolution. Without going into a lot of detail, the simplest explanation is that the coils do not have enough time to build a strong magnetic field at high rpm, and so the spark continues to weaken as the engine speed increases. The bean counters don't give a ****, because this system works great at low speed, and gives good mileage and driveability. This is the number one priority, even in a sports car.
Buy an MSD 6A
Luckily, this is easy to fix. Buy an MSD. In case you didn't hear me the first time, Buy an MSD! Every vehicle on the planet should have one, even your grandmothers grocery getter. The MSD is a capacitive discharge system, which does not loose spark intensity at high rpm. Capacitive discharge systems deliver a very strong, but short duration spark. To overcome this, the MSD delivers multiple sparks over twenty degrees of eccentric shaft duration. This amounts to as many as six sparks at idle, and as little as two at high rpm, but no matter how many times it fires, the spark always lasts for a full twenty degrees. This is the best of both worlds, a high intensity, long duration spark. Just about every racecar on the planet has one, and you should too.
I have installed many MSD's, and the results were always more power, better driveability, and better gas mileage. A second or third gen. will require three boxes for the entire ignition system. This is quite expensive. You can make a large improvement by simply buying one box for the leading, and the results will be even better if you replace the stock dual coil with two MSD Blaster coils. Simply run both coils from the same MSD box. The ultimate setup is of course three MSD 6A's, and four blaster coils, but this will set you back about $700, and you probably will not fit all of this under the hood.
Well, that's about it for the second and third gen RX's. I am currently testing spark plugs, and I will post the results in the future. There is more power here than I thought, especially after I got away from the conventional NGK's. As soon as I have some dyno results, they will be on the page.
Distributors Suck
Now for the first generation. Distributors suck! Distributors require that the charge jump a .075" gap from the rotor to the cap before it can even fire the .055" gap of the spark plug. The gap in the distributor cap is easier to fire than the spark plug gap, because there is much less pressure, but it is still a really shitty way to make fire. Luckily it is relatively easy to convert the leading ignition to direct fire. I finally got around to doing this on my 13B, and then I was mad at myself for not doing it sooner.
Before the conversion, I was using an MSD 6A, with an Accele super coil. This is a lot of juice, so I was really surprised at the improvement after converting to direct fire. I called MSD to be sure that their box would fire two coils, and their tech guy said "Hell, it would probably fire a whole row of coils." I set it up with two stock coils for the leading ignition and was stunned at the results. The engine made more power everywhere in the powerband, and the driveabilty improved dramatically. I will never again run an MSD through the distributor.
Here's how it works. All you need is an MSD 6A, and an extra coil. Two for the leading, and one for the trailing. Trigger the MSD with the magnetic trigger inside of the distributor.Do not try to trigger the MSD with the ignitor! The ignitor output is very "dirty", and does not give the MSD a clean signal to work with. Simply cut the green, and red wires that go from the leading magnetic trigger to the ignitor. The leading ignitor is the one facing the front of the vehicle. Connect the green wire from the trigger, to the purple wire of the MSD, and connect the red wire from the trigger, to the green wire of the MSD. Wire power, ground, and ignition as per MSD's instructions. The orange, and black 16ga. wires from the MSD go to the coil. In this case, make two jumpers and connect both coils to these wires. Make sure that the polarity is correct. The stock coils are labeled positive and negative. The orange wire goes to positive, the black wire goes to negative. Do not screw this up! The same goes for the magnetic trigger in the distributor. If you wire the trigger backwards, the timing will be advanced by approximately thirty degrees. Now simply run a plug wire from each coil to a leading spark plug. It doesn't matter which one, because they will both fire at the same time. Leave the trailing ignition just as it is.
This is referred to as a "wasted spark" system because eack rotor recieves an additional spark during the exhaust phase. On a rotary, this extra spark is actually beneficial, because it fires at the trailing end of the chamber which is where most of the unburned fuel is concentrated. Igniting this fuel will not make more power, but it will clean up the emissions slightly. DO NOT try this setup on the trailing ignition. Because of the different spark plug location you will ignite the incoming mixture from the next stroke. At best, you will lose power, at worst, you will break apex seals. If you have any questions about this, feel free to send a message. This is a simple wiring job, and the results are amazing. This is cheap power, and the improvement in gas mileage will probably pay for the MSD in a years time. I have not tried this with upgraded coils, but when I do, I will let you know if there is further improvement. I am only sorry that I didn't try this on the dyno so that I could measure the improvement in horsepower. Next time I have a 12A on the dyno, I might do a comparison, and post the results.<p>
Spark Plugs
I have been doing some spark plug testing recently, and have been surprised at the results. I have been doing this testing on my daily driver, a bridge ported 13B. Almost everything starts here, and then makes its way to the dyno if the results seem worthwhile. In this engine, I have had the best luck with the Autolite 2526. You know, those cheap nasty plugs that they try to sell you at the discount auto parts store. These plugs have only one ground strap, instead of four like the NGK, or ND plugs. If you look at one of these, it makes sense that they would produce more power because the spark is much less shrouded. This will allow the flame to travel more easily from the face of the plug to the combustion chamber which is a big problem with the rotary anyway.
I should mention that these plugs do not work well without an MSD. It seems that the gap is to great for the stock ignition system to fire consistently. I found that with an MSD on the leading, and stock ignitor on the trailing, that these worked better in the trailing position than the NGK's. However,a friend with a completely stock ignition found that they just plain didn't work as well as the NGK. Until I have a chance to check this out myself, I will not reccommend them for stock ignitions.
After trying every plug made for the rotary, and finding that the cheap Autolite worked best, I decided to call Autolite and find out why. This plug was only available in one heat range, and so I at least wanted to know if they had something similar in a hotter and cooler plug. I was very lucky to contact Don Ward who is an engineer in charge of their motorsports program. I explained all of this to Don, and he agreed that the spark was less shrouded, and this is why they made more power. He also expalined that a resistor plug was prone to misfire above about 7000 rpm. I didn't know this, and so I expalined to him that I was stupid, and asked what he recommended.
Autolite makes an extended tip non resistor plug that is available in four heat ranges, and costs a whopping 99 cents. The extended tip helps to further unshroud the spark, and also moves the electrode .060" closer to the rotor housing surface. This is a conventional style plug, with the ground strap reaching all of the way over the top of the electrode. I ground this off to convert it to a side fire, set the gap to .055", and headed out to the truck to install them. Oops, they didn't fit! This plug has a very short shell, and so the socket needs to extend not only beyond the boss on the rotor housing, but beyond the flat surface as well. Have die grinder will travel! Twenty minutes later, I had the plugs installed in the leading position and Holy ****! I never thought that a spark plug could make such a difference. Power improved throughout the rpm range, and it was much smoother at high rpm.
These will definetely be tested on the dyno, and I promise to post the results so that you can see it for yourself. The next step is to replace the sealing washer with a thinner piece to get the spark an additional .040" closer to the combustion chamber. I will try this on the street engine as well, and these plugs will be comparison tested on the E-Production engine which will be on the dyno the last week of October.
Spark Plug Update 11/3
Well, I recieved some new plugs from Autolite. This is a plug that was developed for Nascar Winston Cup racing on the superpeedways. It just happens to fit the rotaries. It is a 5/8 hex, and so it will fit without modifications. The plugs that I recieved (part number 3910) are prototype pieces, and I am still not sure if they will be production pieces.
These plugs were designed to withstand hundreds of full throttle laps. They are an extended tip design, but they look very much like the BUR-EQ's. They have four ground straps, that are part of the shell, rather than being welded to the shell. So, to get down to details, they extend so far into the rotor housing that the center electrode is only .030" from the apex seal. If you were to install these without the sealing washers, they would protrude into the chamber and munch your apex seals. For the sake of comparison, they are nearly .100" longer than a stock plug.
So how do they perform? Not as well as the modified 99 cent plugs. They do however perform better than the stock plugs, and they will withstand just about anything that a race motor could do to them. But this is not the end of the story. I milled off three of the ground straps, and reinstalled them. Once again unshrouding the spark paid off. The difference was amazing! They work GREAT! So far better than anything I have tried. Autolite says that these plugs will be expensive. Probably in the 5 to 8 dollar range, if they are even produced at all. If these are not produced, it will not have been a waste of time, because they helped illustrate the importance of unshrouding the spark.
As an alternative, I am searching the manufacturers catalogs for a non resistor, 5/8" hex, extended tip plug that will reach as far into the housing as these do. If I can find something in the appropriate heat range, it should work every bit as well, as the testing seems to indicate that there are only two important factors. 1. Getting the spark as close as possible to the chamber. 2. Keeping the spark as unshrouded as possible. If I can find something with a 5/8" hex, they will fit without grinding, or investing in a $50 spark plug socket.
ANOTHER Spark Plug Update 12/4
Well I finally found what I was looking for. Champion makes an extended tip non resistor plug with a 5/8" hex. It is available in four heat ranges. These plugs have the same configuration and dimensions as the Autolite 51's. So far I have been very disappointed with the life span of the Autolites. I was reminded by a friend that at 99 cents a piece it doesn't really matter, but there has got to be something that works, and lasts longer. The Champion plugs cost about $2.50 each, and the part numbers are C57YC, C59YC, C61YC, and C63YC. The heat range is equivalent to an NGK 7, 8, 9, and 10 respectively. They do require trimming of the ground strap just like the Autolites, and after closer inspection I realized that after trimming they do fit in the trailing position. I have not been driving my truck for the last month, so I cannot yet say how the power is, but being the same configuration as the Autolites I would imagine that they work as well. As for life expectancy, I don't know that yet either. So why am I telling you this? So that you will try them yourself, and give me some feedback. I will compare these to all the others on the dyno, and post the results, but this could be a month or more away.
I will eventually figure out what works best, and how long they last compared to the stock plugs, but I do have to pay the bills. In the meantime, I would really appreciate feedback from any of you who wish to experiment with these plugs. When I finally decide on a particular plug I will post the dyno results, so that you can see the results for yourself. When this is all finalized you will all be able to go a little bit faster for pocket change.
ANOTHER Spark Plug Update 6-22
OK, here we go again. As I mentioned before, the Autolite didn't last long. The Champions were even worse, and turned out to be quite fragile. I finally scrounged an NGK Sportline Catalog from a local motorcycle shop, and guess what I found. A 14mm., .750 reach, extended tip plug. BP-ES Pay dirt! Same design and dimensions as the Autolite and Champion extended tip plug. After performing the same modifications I installed them, and beat them to death. They are very tough. Just to be sure, I installed a BP7ES in the leading position which is a bit hot for an extended tip plug. I have driven around with these 7's installed for nearly a month now, and even gave them the torture test by running 90mph on the freeway for several miles. This is normally no big deal, but since the plug is too hot for this application it really put them to the test. After this I examined the ceramic with a magnifying glass, and could see no signs of cracking. The performance is the same as the other extended tip plugs, but they are much more durable. They are available at most motorcycle shops in two different heat ranges. BP7ES, and BP8ES. A BP9ES is also available, but the local shops do not stock it. They can be ordered however. The only downside is that they are a 13/16 short shell plug, and you will need a Racing Beat spark plug socket to install them. NGK also makes a racing version of this plug available in heat ranges 7,8,9, and 10 They are a 5/8 hex, so no special socket is required. The part number is R5400-heat range number. They have a fine wire gold palladium center electrode, which will reduce the voltage required to jump the gap. This may be helpful if they are used with a distributor, and stock ignitors. These are "race" plugs, and are quite pricey.
Do not forget that these plugs must be converted to side fire configuration or they will protrude into the combustion chamber and break your apex seals. I will probably purchase a case of each, and cut the ground straps on the mill. I do not yet know what the pricing will be.
Next months technical article will discuss the ignition system, and further recommendations will be made at that point.
I hope that this section of my webpage has been beneficial. After the dyno testing, I will finish this section, and polish it up a bit so it doesn't sound like the mad ramblings of someone who has nothing better to do than change spark plugs, and race around the neighborhood. For now, please excuse the typos and grammatical errors on this page.
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