spark plugs

[Guest]

Hello guys,
When my bike is running, and warm, I bring the rpm's up to about 2500 and then up to 3000. When I do this the bike hesitates a little, but picks up pretty well. I figured it was running a little rich, or lean, so I reved between 2500 to 3000 for awhile and pulled the plugs to find that they are a dark flat black color. Does this mean that I am burning oil? I thought that if I would have been running rich that the plugs would be shiny... I hope im wrong......
Any help/opinions are greatly appreciated,
Nick

[Nicholaschase29]

Also, the bike has 41k miles on it and the test was done in neutral, not driving. Another thing that happens is that when I wind it up and does'nt really have that much power as it normally does at about 7-10k rpm. It feels like the exhaust is getting plugged or something, but this could just be from bad jetting.
Thanks,
Nick

[Nessism]

In order to get a proper plug reading you need to drive the bike, not rev at a stop. Also, it helps of the plugs are clean and fresh.

Did you make any changes to the bike before it started to run poorly?

[chef1366]

If it was oil it would be glossy and almost look wet. I can't tell you which jet is rich by RPMs. I could tell you by throttle position. Mark your throttle 1/8-1/4-1/2-3/4. Between idle and 1/8 throttle is your pilot circuit.(pilot jet and idle mixture screws) After 1/8 throttle your needle starts to rise out of your needle jet which allows fuel to flow from your main (Needle circuit) Anything above 3/4 throttle runs from the main jet .(Main jet circuit) I remember you saying that you shimmed your needle. If your problem is in the needle circuit than you should remove one (shim). If it's in your pilot circuit than you need to lean out your idle mixture screws or your pilot jet is too big. You never answered me if the pilot jet is Mikuni.

[Nicholaschase29]

i drilled the fuel jet (the thing the needle slides into) oversized 2 thousands, plus I pulled the needle washer/plug off the top and added 1 shim, I would guess about 1/6 the size of the washer/plug. This would lead me to beleave that I would need to put 2 more washers on top of each needle, to lower the needle abit.
Let me know what you think,
Nick

[Nicholaschase29]

I also went from 12 to 8 disks in my supertrapp exhaust

[BentRod]

http://www.dansmc.com/spark_plugs/spark_plugs_catalog.html

compare here. very extensive.

As to the hesitation
From a technical point of view, the performance of an engine is dependant on everything from the timing of the spark, to the carb set up, from the diameter of the muffler's exhaust to... you get the idea. my point is it may not just be your carbs. Tried any different fuel setups?
What is your exhaust set up? anything special about it?
Certain sources of knowledge and experiance far surpassing my own have previously stated that some non-stock exhaust setups can cause flat spots in your power band.