benwall Posted January 24, 2011 Report Share Posted January 24, 2011 Are NGK Iridium spark plugs worth buying instead of the standard ones? and how big of a diference do they make? 1 Quote Link to comment Share on other sites More sharing options...
dgshannon Posted January 24, 2011 Report Share Posted January 24, 2011 Are NGK Iridium spark plugs worth buying instead of the standard ones? and how big of a diference do they make? Kind of like those balance/strength bracelets. Any difference would only be in your head. Special materials such as Iridium, Platinum, etc. are great for extending the useful life of the plug. Not a feature that you really need in a trials bike. As far as a performance gain goes, something that you will notice while riding the bike, that is not what they are all about. Quote Link to comment Share on other sites More sharing options...
telecat Posted January 24, 2011 Report Share Posted January 24, 2011 Kind of like those balance/strength bracelets. Any difference would only be in your head. Special materials such as Iridium, Platinum, etc. are great for extending the useful life of the plug. Not a feature that you really need in a trials bike. As far as a performance gain goes, something that you will notice while riding the bike, that is not what they are all about. And We've used them for 5 years. Reliable, unbreakable, no performance drop off. You won't get any more power or MPG but I haven't had one fail or even get close since we started using them. They do seem to resist "oiling" up better than standard plugs as well. I've used about 5 in 6 bikes. They just keep on sparking. Quote Link to comment Share on other sites More sharing options...
dan williams Posted January 24, 2011 Report Share Posted January 24, 2011 Proper heat range of plug and jetting will accomplish that. Iridium is extremely hard so it doesn't erode from the spark the way a conventional electrode will. They were developed for automotive applications where plugs are now expected to last for 100,000 miles. No real benefit for a trials bike short of the pointy electrode slightly reducing the tendancy to foul. A platinum plug has the same advantage for a lot less money. Quote Link to comment Share on other sites More sharing options...
richt Posted January 24, 2011 Report Share Posted January 24, 2011 And We've used them for 5 years. Reliable, unbreakable, no performance drop off. You won't get any more power or MPG but I haven't had one fail or even get close since we started using them. They do seem to resist "oiling" up better than standard plugs as well. I've used about 5 in 6 bikes. They just keep on sparking. Some tech info on the NGK website explains that a smaller electrode is less likely to suffer from 'Fuel Quenching', a small electrode reheats quicker and reduces the chance of fowling. Iridium is used because it is 6 times harder than the usual material and makes the plug last longer! Just technology, I just need to learn to ride! Quote Link to comment Share on other sites More sharing options...
twinshock Posted January 24, 2011 Report Share Posted January 24, 2011 I had an Iridium brand of plug supplied to me as part of a sponsorship deal and as a more mature aged rider I was fitting them to several Fantic's, a 200, 240 Pro and two 305's and also to a Pre 65 Tiger Cub. They ran ok in all bikes when first fitted but I found they only lasted about 3 trials before they failed suddenly and without warning, they weren't NGK's. Free or not I don't use them any more as an NGK lasts me a lot longer and I don't have the hassle of changing plugs half way round a course on the side of a mountain. Cheers Quote Link to comment Share on other sites More sharing options...
copemech Posted January 25, 2011 Report Share Posted January 25, 2011 This topic usually sparks(pun) similar experiences accross the board. Fact is one must be very careful when changing plugs nowadays, specially when changing brands, as they are not all equal, and some will simply quit running! I could tell you horror stories about all this in automotive applications. They can do some jikky stuff with the computers and such! Long story made short, if the bike was speced for say a NGK BP5ES(non resistor), and you went with an Irridium BPR5IEX or whatever it is, they cost a lot and even though I have heard no complaints, I doubt you would gain much except some resistance to fouling, given they are set to the same gap. The bike seem to tolerate the resistor, but I would not push things here as trials motors have no excess ability to produce spark, which is why most limit the gap to .5-.6mm range to begin with. Adding the resistor potentially nullifies any excess spark availability you may have had. Where as if you went from the standard plug to a BP5EVX Platinum, it would cost less, you would have similar properties, and without the added resistor, you might just be able to take advantage of the better electrical properties of the conductors and(within the limitations of the system) open the gap slightly to a true .6-.7mm range to gain a bit beter flamefront propagation and cleaner running off the bottom. One must be careful here, as under high engine loads, it could flame out once you have reached the limits of the little ignition system to produce reliable voltage, specially at low revs and high throttle loads. All said, I am still running the same VX platinum I installed in '07. Worth the money? Not sure, as I still carry a spare! Quote Link to comment Share on other sites More sharing options...
dan williams Posted January 26, 2011 Report Share Posted January 26, 2011 The resistors don't have much effect on the initial spark as the gap has giga-Ohms of resistance before the initial pulse breaks down the resistance. In series with a 5k Ohm resistor the effect is negligible. What it does affect is the rise time of the current after the initial spark is made. This is the reason for the resistor. After the spark is started the resistance of the gap essentially goes to 0 and the current from the ignition coil is dumped across the gap. How fast this current level rises determines the amount of radio frequency harmonics generated by the electro-magnetic field emitted by the coil/wire/plug. Same as a lightning bolt on your radio. Unfortunately with all the computers in cars these days that radio noise gets into the electronics and wreaks havok. From a practical ignition standpoint the slower risetime of the current means the spark will last a little longer but will be less hot as it limits the peak current the coil can deliver. As far as damaging the ignition system going resistor/non-resistor it's extremely unlikely to have any significant effect on a trials bike unless it has a poorly shielded computer sitting next to the plug wire. Now having said that most of your ignition systems since the early 90's have microcontrollers in the CDI box so.... Quote Link to comment Share on other sites More sharing options...
spark Posted January 26, 2011 Report Share Posted January 26, 2011 I have been using the iridium plugs in my bike for a couple of months now and it does seem to start more consistently than with the original plug. I don't wear a Power Balance bracelet so my opinion should be worth something right? Quote Link to comment Share on other sites More sharing options...
dan williams Posted February 6, 2011 Report Share Posted February 6, 2011 Absolutely your opinion is worth something. Sorry if I seemed to imply otherwise. There are a lot of engineers that ride trials and we tend to need explanations. Nothing personal in it just driven to obtain data, weigh it and try to understand root causes. We get all cranky when the data doesn Quote Link to comment Share on other sites More sharing options...
spark Posted February 7, 2011 Report Share Posted February 7, 2011 No don't worry Dan I wasn't offended at all. Perhaps I should have stuck a smiley face at the end of my sentence, but I sometimes forget the serious tone of this forum. Quote Link to comment Share on other sites More sharing options...
dan williams Posted February 7, 2011 Report Share Posted February 7, 2011 Heh heh There are no rules and you break them at your peril. Quote Link to comment Share on other sites More sharing options...
copemech Posted February 8, 2011 Report Share Posted February 8, 2011 Some bikes do specify the resistor plug(accept reasons stated) and others not. I tend to agree with the overall easier starting, which also playes along with the somewhat cleaner running at lower revs. Primarily, I would attribute this to the bit more open design of the smaller electrodes along with a more consistant arc placement as compared to a more massive electrode which has someting of a shielding effect. Some truely high performance engines actually index plugs so the electrodes are in a set direction as not to shield themselves from the incoming mixture. In piston aircraft use, it is said the fine wire platinum electrode plugs pay for themselves in fuel economy, being more efficient than the massive electrode counterpart. They are very expensive! And two per hole! The importance of good spark does become more apparent in aircraft use, with two plugs per cyl running off two separate mags for redundancy. On a normal run-up, you kill each mag to see what happens and to tell if the other is working. At a medium power setting, you will normally loose 75-150 rpm, when one or the other is lost. Quote Link to comment Share on other sites More sharing options...
dan williams Posted February 9, 2011 Report Share Posted February 9, 2011 My other observation was going to be how many pilots ride trials. The dual mag/plug thing makes sense. Two flame fronts will raise the pressure in the cylinder faster so if the engine is designed to expect two flame fronts there will be a small percentage of unburned mixture or at least not burned at the optimal time to make power. Quote Link to comment Share on other sites More sharing options...
copemech Posted February 10, 2011 Report Share Posted February 10, 2011 Dan is playing devil's advocate here, and I agree with him. Long story made short, all the hype from plug makers is mostly marketing BS. I have seen some horrid designs, and results. If your bike or car or whatever specs a certain plug, you are well advised to stick with it, not another brand or style from another maker, or even the same maker in some cases. The only real thing positive in respect to trials bikes seems to be the NGK plugs which are speced for many bikes seem to work well in their platinum and irridium varients and seem to offer a better resistance to fuel and oil fouling. At the same time I say that, someone willcome along and putt around all day never cleaning out the bike or getting any heat into the motor and foul a costly plug! I have been able to run a slightly more open gap at .7mm reliably for years now, but would be hesititant to recommend it to all because the systems are limited, and may not support it. You are your own test pilot here! I do not even push my own luck here for the sake of experimentation. I let young and dumb volunteers do that work! The standard plugs are cheap! I have gone all season on one, then chunk it! Also chunk them at the first signs of hard starting and such. Seems they may give a bit of warning if you listen. Quote Link to comment Share on other sites More sharing options...
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