if you're running at a track you should be fine, they need about 450 degrees c to self clean. you should be ok, and I'd imagine the RS engine is well suited to them. Can 1037 or MrR elaborate?
Haha. All this from a humble plug question. How long should I expect my iridium plugs to last then? Am I changing them too soon?
Just to add to my posts, my 748R engine which used the surface discharge plugs is stock but is in a 748S frame so I can only use stock small injectors and airbox etc. it was dynoed by CJS and the fuelling set up from scratch over the whole range and I use Magnecor plug leads. But in spite of this it still does not run as well on surface discharge plugs compared to stock type plugs. No doubt If I used it on the track only the surface discharge plugs would work better than they do but it's not worth (in my opinion) changing them over every time I use it on track as I have tried this and can feel no difference.
Iridium plugs can be left in for up to 50,000km in some cars, supposed to resist fouling especially in lean burn motors. Also because iridium resists spark erosion of the electrodes far better the plugs can run finer electrodes giving better sparking characteristics, well that's how I understand it anyway.
Herewith Shazaam's take on this. He suggests, although you will not increase power necessarily, you should increase throttle response. He reckons to be a Ducati Guru but I'm certain he's wrong about the quiet clutch mod, so who knows if he's right about this... Platinum and Iridium Spark Plugs The initial reason this type of plug was developed was to extend plug life due to US EPA-mandated exhaust emission system low maintenance requirements, not because they offered any improved performance over conventional electrodes. They incorporate electrodes made of harder materials that erode more slowly and consequently don’t need to regapped as often. The big benefit to having platinum or iridium as an electrode material is that the harder material erodes more slowly and consequently allows you to reduce the size of the center electrode and still have a long-lifetime plug. But remember, a smaller electrode will initiate an arc at a lower voltage. Consequently, you should NOT run these plugs at the factory recommended gaps. If your coils and wires are weak then a smaller gap will reduce misfires, but should be applied only as an interim measure. NGK and Denso pre-gap their Ducati application iridium plugs to 0.035 inch. This should be considered a MINIMUM gap for this kind of plug. Their smaller electrodes fire this larger gap at about the same voltage as a conventional plug fires the factory recommended gap - with one added benefit - a strong spark kernel across a larger plug gap = improved throttle response. Consequently, dyno testing shows a performance gain with specialty plugs only when their intrinsically lower arc-over voltage has allowed users to increase the plug gap above that possible with conventional steel electrode plugs. Try increasing the gap beyond 0.035 inch for further improvements. You should be able to go to 0.040 inch on a new superbike. Said another way, platinum or iridium plugs in your Ducati will give you worse performance than a conventional plug unless you use a larger gap than is recommended for the steel electrode plug equivalent. I have seen repeated examples of poor Ducati running and throttle response problems cured by replacing platinum or iridium plugs that were gapped too small (i.e. at the 0.024 in. Ducati recommends for conventional plugs.)
According to Shazaam, the improved burn which gives better throttle response only happens if you use at least the factory-set increased gap that comes as standard on the iridium plug. It's apparently a bad idea to reduce this to the recommended gap for more conventional plugs.
Let's try English, rather than American English... I understood it to mean that Iridium will last longer much than conventional plugs and can also give better throttle response but only if you use at least the factory set gaps, which are larger than the Ducati recommended gaps, which are for conventional plugs. There is a danger that the increased gap will put too much load on old plug leads though, so it's a good idea to replace them. However, am I right in thinking that the stick-coils on my 999 will eliminate this problem??
Sorry, misunderstood you. I fitted some Iridium on the strength of this and just stuck them in with the supplied gaps. They work well and never foul. They appear to give better idling and throttle response but that's an entirely subjective judgement. 35 thou = 0.889 mm - standard gap is of course, 0.6 mm or 24 thou, so the preset Iridium gap is a whopping 50% larger than the recommended gap for a copper plug.
Arreste Severianus! 0.7mm is not the answer to your question. You asked what 0.035 of an inch is in new money and the answer to that is 0.889mm or effectively, 0.9mm This is the preset gap that Iridium plugs tend to come with. When I was debating whether to go Iridium or not, I did a lot of reading on the subject and the received wisdom appears to be that the larger gap that Iridium plugs allow should give a 'fatter' spark. This should but will not necessarily give benefits of improved starting (if your starting system is strong enough) and fewer low-speed misfires, so better idling and smoother low-speed running. Throttle response should improve but not outright power. That appears to be the theory and subjectively did seem to be borne out on the road but I may be kidding myself. I haven't suffered from any fouling though, the bike always starts on two cylinders, never on one with the other one chiming in a little later and, of course, Iridium plugs are supposed to be pretty much fit and forget, with a life of tens of thousands of miles. For some I think this might be a downside though because fitting nice new plugs along with nice new belts and nice new oil and filter does have its own feel-good factor. Vector Antiquus
It is the fine wire electrode that enables the use of a larger gap without loading the ignition system. And just to be nitty picky. 0.7mm is actually 0.027559", nearly 28 thou.
Oops, didn't check this properly...:Shamefullyembarrased: Have now corrected. So that's even more dramatic - a recommended 0.6mm to a preset 0.9mm (closest equivalents) is a whopping 50% increase in gap size. No wonder it seems to start better...
If you look at the your quote from Shaazam again you'll see what he means about the gap size and voltage. With "stick" coils there are no plug leads. The coils are mounted directly on top of the plugs. The wires are just the same low tension wires that would also be connected to a conventional coil. Rather than the plug leads failing with too big a gap a bigger concern would be a breakdown of the coils internal insulation where the spark occurs inside the coil instead of at the plug points. This would be just as possible with a stick coil as a conventional coil. I've alway run my Ducatis with 0.9mm plug gaps, ignition system is well up to it even with conventional plugs and the carbed models benefit from it greatly with a much reduced tendency to foul the plugs. I don't always agree with Shaazam's declarations and I haven't read his spiel about the quiet clutch mod but as one who has run the mod for over 40,000 miles on one bike and about 5,000 on another with no problems I'm happy with it. Don't know about this "proper guru" thing either :Shy:
Derek Tech Guru A reference to the above status on Ducati UpNorth of course.... This is the part of Shazaam's clutch article I believe to be incorrect: "Quiet Clutch Mod It’s been sugested that adding a plate at the bottom of the stack will reduce clutch noise. This plate is not an addition to the existing stack, the stack height has to be maintained. This is a rearrangement of plates in the stack. The idea here is to move the friction plates to a new location in the stack so that they no longer are alligned with the notches in the basket (notches that they caused previously.) This in turn reduces the tab-to basket clearances for the friction plates so you get less noise." 0.9mm for conventional plugs! Wonder why Ducati specify such a small gap then??
normally Derek any OEM setting is probably more driven by a need to get it through emissions vs performance compromise to get all their EU and california ticks in the boxes.
Ah yes, rather like their carb settings for the SS. If you read the workshop manual, they say as much, reading between the lines and give you altogether different settings for "racing" or however they put it. Vector Antiquus
