poor running 996s
 

Hi, my 996s (2001) is running very poor between about 4000rpm and 6000rpm, this seems to happen when under load when it gets past this it runs fine and when below it runs fine. the engine has just had an expensive re-build (1 crank and 2 con rods ouch !) but this was a problem before that. I have 50mm termis' on it and thought that the chip might be a wrong match so i got one from jhp but if anything this seems to make the problem slighty worse. I got my local ducati dealer to take a quick look and he set everything up and checked it (though he didnt tast ride it) but he found nothing obvious wrong. my next step will be new plugs and then a fuel filter unles anyone can point me in the right direction, as for the plugs which ones are the bike supposed to have or run best on,, in it at the moment are ngk r dcpr9e, again any help is very much welcome

Same rpm in every gear?
Could be the TPS.:puzzled:

yes the same rpm in every gear. Tps ???

ah !!! throtle position sensor, it was also set.

The plugs I run in my 916 are the NGK DCPR9EVX Platinum tipped ones, usually need re-gapping as the gap they come with is usually a little to big, I use 0.6mm spark gap

Skidlids, try using a larger gap with platinum plugs for better throttle response.

The initial reason this type of plug was developed was to extend plug life due to US EPA-mandated exhaust emission system low maintenance (longer replacement periods) 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 using platinum or iridium as an electrode material is that the harder material erodes more slowly and consequently allows the manufacturer to reduce the size of the center electrode and still have a long-lifetime plug. However, a smaller electrode will initiate an arc at a lower voltage producing a weaker spark.

Consequently, you should NOT run these plugs at the factory recommended gaps for conventional plugs. If your coils and wires are weak, then running a smaller gap will reduce misfires, but should be used 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. 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.

Consequently, dyno testing shows a performance gain with specialty plugs but 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 throttle response 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.)

A good ignition system needs to be able to ignite the combustion chamber fuel-air mixture with as few misfires as possible (there’s always a few.) When you reduce the number of missed combustion events, you improve overall power, fuel economy, and particularly, throttle response. Generally, missed ignition events are most likely to occur during throttle transitions when the fuel-air mixtures are changing rapidly. This is usually described as “poor throttle response”, the inability to respond rapidly to throttle inputs.

In fact, this is the principal behind ignition amplifiers which is another way to fire a larger plug gap by increasing 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 HP improvement. Again, the main benefit here is throttle response.

I'm slightly amazed that someone would go to all the trouble and expense of rebuilding a motor like that and not even treat it to new plugs!

I agree, so its of this morning to get new plugs , and hope it makes the difference

Shazaam, I may try the bigger gap next time, but throttle response appears fine to me.
I'm not overly confident of the ability of the standard coils to produce a big spark across the larger gap.
On previous bikes I have used Dyna and Circycle coils especially on highly tuned motors.
Had a monstrous CB900 engine once(1984), very high compression big bore kit on it, Standard Ignition would only let it Rev to 6000rpm, platimum tipped plugs added almost another 1000rpm with Circycle coils adding another 1000rpm. In the end to get it to rev out I had to fit a Mistral ignition system exactly the same as used by the Team Bike Endurance team.
So I appreciate how important a good ignition system is.

I have found that standard road engines aren't to happy with the surface discharge plugs like the Champion A55V and I will reserve those for the 955 race engine

new plugs got this morning from ducati and fitted them, though the poroblem is still there but not as bad as it was, i'll take them out again and check the gaps as per manual , still if anyone has any ideas i would be greatfull to hear them, cheers.