Spark plugs heat range

Does anyone recognize this:

I do a 20km trip to work and back everyday on my sport. I can take 2 different ways. One is an open fields road where i can open up the throttle and never have to wait. The other is a slow road with traffic lights and slow cars i cannot pass. Of coarse i use the first road. But there is a road block for the moment.

When i take the slow road, the bike starts fine, idles fine, but after a while of slow traffic it starts to back down, misfire etc. It did that always, even after installation of open silencers/remap. Only when i hit a few miles of highway, it gets better.

Now, it looks like the plugs are fouling at low speeds, and especially when opening up the throttle after a while of slow driving. It can take up to 2 seconds or so for it to react to the throttle. When driving hard, there are absolutely no problems. And a few minutes of driving slow do not cause this. It is only after 10 minutes or more behind a truck or slow car.

Anybody tried a hotter plug to cure this problem? Standard is a pretty cold plug (CR9EB). I guess trying a CR8EB would do it no harm?

In my racing experience 1 heat range up or down is safe especially with NGK. A 9 is a racing plug. These bikes are setup to run hard and prefer to run that way. Please let us know what you find out

Could it simply be "overheating" in the slow traffic ??

If that's the case it would be a very bad idea to install a hotter plug. But i think not it is overheating at all. I don't feel any difference in cold or hot weather. I am going to put a spark plug wrench in my bag and check the plugs first the next time it happens.

find a dyneoand put a load on it, so easy to duplicate the condition with a dyne.

I have a dyno available indeed. The easy part is to duplicate the condition. The hard part is finding time for it. A plug chop on my way to work is easier for me.

But since i scuffed my right side silencer yesterday, i might as well invest some extra time and go for the 'make my own decat pipes'-route, repair the scuff marks and ceramic coat the complete system for the fraction of the cost of a new silencer. And have a custom map made (if possible, i asked) based on dyno results. In that case the problem 'should' be cured by the map.

Id be interested to know if the fueling can be custom mapped by an independent dyno...

The tuner would have to crack the codes on the Orex Ecu or fit a Power Commander or similar unit.

An independant dyno guy would not have the right software to do a custom map for sure.
My question to my dealer was if they do. It could be their software only allows pre defined maps to be uploaded.

The ecu's changed also somewhere along the line. I have an early type (don't ask me what it is exactly). It is a different ecu as the new 961's.

Did not receive an answer yet.

Well... got some answers so far.

The custom map for open exhausts are indeed pretty rich according to my dealer. The spark plugs never get burned clean on their bikes either. He thinks it is a good idea to try a hotter grade plug. You can even go to CR7 if conditions are not extreme (long distance driving on hot summer nights).
They don't do custom maps yet. I forgot to ask if it is possible.

For now i will try a grade higher in plug heat range. will post the results asap.

Do let us know!