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  #21  
Old 25-Jun-2003, 16:42
DJ Tera DJ Tera is offline
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Maybe a power commander would help then?
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  #22  
Old 25-Jun-2003, 21:06
998Addict 998Addict is offline
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Chillo

I understand you might not have the same alarm, and this might sound like I'm pushing a theory you want to discount, but could it not be alarm-related as well?

Look at the symptoms:
1. Respected people think its electrical
2. It sounds electrical
3. It's not so bad on a dyno (less vibration)

Sorry to press-on about this, but couldn't it be worthy of investigation?
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  #23  
Old 25-Jun-2003, 22:56
Matthew Smith
 
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Take it to John Hackett, he should be able to sort it and it should'nt even cost you.

If he can't then it's your decision, i would send it back and get the new 999R than put up with it...
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  #24  
Old 26-Jun-2003, 00:10
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chillo chillo is offline
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998 check your u2 inbox mate.
Went out on it tonight and it will rev cleanly in 1st and 2nd to the rev limiter.
Misfire starts happening in 3rd and 4th getting progressively worse the faster i go.
I've never revved it hard in the first gears mainly because it revs so dam fast its like a turbo!
If JH is at the track day on Tuesday i will try and talk to him then?!

[Edited on 25-6-2003 by chillo]
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  #25  
Old 26-Jun-2003, 00:44
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Chillo. Spoke to John hackett today about your prob. He's word's were, "that aint right" tell him to bring it down its covered by warranty. As for brake pads I think Felix said it all. I run bendix as reco'ed by PFM, I like em. Just got the Bucci slipper with carbon plates. J.H took time out to put it together for me and explain the workings and what will go wrong if put together incorrectley.

Jon
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  #26  
Old 26-Jun-2003, 00:59
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DSC Member Shazaam! Shazaam! is offline
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Since new, Chillo's 998R will not rev past 9,000 rpm in 6th gear (indicated 160 mph), but will stutter through the 9,000 rpm point in 5th gear. In 4th and 3rd gear it revs through the 9,000 rpm point easier, and easier still in 2nd and 1st. When the bike was dyno'ed, it ran cleanly to 10,250 rpm.

The way he describes it is, it's like the bike is being switched off/shut down for a fraction of a second then back on again. It misfires more the faster he tries to go. It's like having a rev limiter set at 9,000 rpm.

To date, the CPU and a couple of ignition relays were replaced, the crank position sensor re-set, and all wiring connections and switches checked.

I believe there's a simple explanation.

The reason that the misfire problem decreases with gear ratio is that cracking the throttle wide open in the higher gears places more load on the engine than when you're in a lower gear. A top gear dyno run places even less load on the engine because the bike is stationary so there's no air resistance loading.

As you open the throttle, a larger mass of air and fuel is admitted into each cylinder, yet it ends up being squeezed into the same combustion chamber space. As a result, air and fuel molecules are crowded closer together and so the fire ignited by the spark plug spreads faster. The more rapid march of the flame away from the ignition point means that the engine then needs less ignition advance.

The timing settled upon for use in the CPU ignition map is one that doesn't produce too much detonation on full throttle at the engine's torque peak, when cylinder pressures are highest. On Ducati superbikes the highest cylinder pressures and peak torque occurs right around 8,500 to 9,000 rpm. Does this number sound familiar?

Further, the fuel/air mixture is hardest to light off when the cylinder pressures are the highest during full-throttle top gear acceleration at the peak torque rpm. If the spark is inadequate to jump the plug gap, you'll get a misfire.

Ducati uses the same coils and wires for all its models, even for the higher-torque 998R so just normal manufacturing tolerances could make these ignition components marginal under the worse operating condition, the one that you've identified exactly, 9,000 rpm in top gear.

So there's your problem.

The solution is to upgrade the OEM ignition components.

You can reduce these misfires if you can increase the size of the plug gap and still reliably maintain the intensity and duration of the electrical arc across the gap. A highly-compressed fuel-air mixture is difficult to ignite, so a larger gap increases the opportunity for fuel molecules to enter the gap and a longer duration, more intense spark allows for a wider window of time for, and likelihood of ignition.

But, increasing the plug gap places higher demands on the sparkplug wires and ignition coils because it takes a higher voltage to fire a larger gap. The coils need to robust enough to supply an adequate spark kernel and the plug wires need to be able to transmit this electrical energy at the higher voltages needed without failure of the conductor or insulation.


Plug Wires

The stock spark plug wires are constructed with a stranded core covered with an EPDM insulating jacket. Like most wires, the conductor itself will last a long time, but the insulation will start to degrade after a couple of years from engine heat which is why most quality aftermarket wire is insulated with silicone rubber.

I recommend replacing the stock sparkplug wires with a set of Magnecore wires. Magnecore #2549 wires for a Ducati superbike cost $67, but other aftermarket suppliers also offer quality EMI suppression wires.


Coils

Ducati’s use an inductive ignition where coils are charged with 12 volts and then apply a high voltage to the sparkplugs when signaled by the igniter. The typical firing voltage is 8–10,000 volts, with higher firing voltages needed for a high compression engine. Once the spark jumps the gap, it only requires several hundred volts to maintain the electric arc while the coil discharges.

The main advantage in using an inductive system is that you get a relatively high current, long duration spark (2,000 microseconds) that works very well for low speed, lean mixtures and partial throttle applications. The main disadvantage is that because it takes a finite amount of time to charge a coil, and at very high rpms there isn’t enough time to fully charge the coil between firings. Fortunately, Ducati street bikes don’t rev high enough for this to be a concern.

Stock coils on early Ducatis can be improved upon by installing aftermarket coils such as those made by Dyna, Accel, or Nology. Their primary advantage is that due to the larger physical size of the coils, the duration of the spark is longer. An intrinsic limitation of aftermarket coils with more windings is that they take longer to charge and discharge, so they have less and less time to cycle as rpm increases. Therefore, their available secondary voltage drops (faster than small coils) as rpm increases.

Fortunately, the newer stock Ducati coils are quite good given that they’ll fire a 0.044 inch plug gap even though the factory recommended gap for standard plugs is around 0.024 inch. Consequently, there’s no demand for aftermarket coils for superbikes.


Ignition Amplifiers

Another way to fire a larger plug gap is to increase the operating voltage of the stock coil.

One product, the Evoluzione ignition amplifier increases the primary voltage to the stock Ducati coils from 12 volts to either 16 volts or 18 volts (user selectable). The way a coil works is that if you put in 12 volts (primary) and get out, say, 12,000 volts (secondary), then if you put in 18 volts you will get out 18,000 volts. Again, this requires coils and wires in good condition.

Evoluzione recommends for best results that you run a 0.060-inch (!) plug gap instead of a 0.024 stock gap on a superbike, the larger gap being the key to getting a stronger spark and increasing the overall likelihood of a combustion event.

One reservation that I have about ignition amplifiers is that they could cause overheating and premature failure of the stock coils or wires. This reliability consideration has to be balanced against improved performance. An independent test by Road Racing World magazine on a GSXR 1000 saw only about a 0.2 peak horsepower improvement. Again, the main benefit here is throttle response.


Spark Plug Gaps

So, if you’ve got good plug wires and coils (and maybe an ignition amplifier) then you can fire a larger plug gap.

If you use conventional sparkplugs, start with the recommended gap and try opening the gap up in 0.002 inch increments. You should note a progressively smoother throttle response if not more power. When the bike begins to lose power (misfires), go back 0.001 - 0.002 inch and this will be your optimum gap.

As a good rule-of-thumb, if you go more than 0.008 inch over the out-of-the-box gap you won’t maintain parallel surfaces between ground and the center electrodes. So if you reach that point, change to a plug that starts at a higher gap. The NGK dash 9 series starts at a 9 mm (0.035 inch gap), for example.


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 re-gapped 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.)



So I recommend first switching to NGK iridium plugs gapped at 0.035 out-of-the-box. If that doesn't clear up your misfire, replace the ignition wires with Magnecore units. The ignition amplifier is likely unnecessary but could be an option.
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  #27  
Old 26-Jun-2003, 11:57
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Rattler Rattler is offline
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WOW!!!!

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  #28  
Old 26-Jun-2003, 12:52
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Chillo, that makes a lot of sense.
JH knows these bikes like no other. Getting a hold of him at the moment though is a 'mare but has to be worth doing.
If you want to play and can't get down to Coventry, give us a call??
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  #29  
Old 26-Jun-2003, 14:35
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DSC Member Monty Monty is offline
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Chillo, I can confirm both John and Rick Hackett will be at the trackday.

John
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  #30  
Old 26-Jun-2003, 14:57
Damo748 Damo748 is offline
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I can honestly say that that is one of the most comprehensive answers that I have ever seen!!!
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