300ex problem

[knaegeli]

I have a 96 300ex. We put a brand new plug in it and went on a nice long ride. When we came back I checked the plug and it was black with soot. This usual means a rich condition right. If anything it should be running lean. It has the stock jetting in the carb, stock pipe. The only thing modified is the K&N filter and modified air box. We live at sea level and the air fuel mixture is set at 21/4 to 21/2. Does anyone have any ideas why the spark plug is still black? It also acts like it is running rich. It is running a 122 main jet in it which is suppose to be stock. Can someone please help!

[400exdad]

Two things: Make sure the choke is off.... as minor as that might sound, it is possible. Also, does it idle well? If it eventually loads up and dies or if fuel drips from the overflow vent you could either have trash in the needle and seat or your float level could be improperly set. To me, those are the easy fixes. My next target would be a look at the metering rod. Is it like its supposed to be? There should be a washer under the spring that holds it down against the slide and clip. Good Luck.

[400exdad]

I had to pull our 96's carb down yesterday due to a sticky slider... I need to correct myself. The metering rod is held in place by a "bracket".... I was thinking of our LT80 in my previous post. :huh

[ghak99]

Is there any way you could have over oiled your KnN? Is the filter clean? I have seen this happen more than once and they tried everything only to have something as simple as an over oiled filter be messing with them.

[dork]

unless you did a plug chop before you pulled the plug, looking at the plug will be pretty much useless. the 300ex carb has an accelerator pump which will make the plug look sooty if you check it after low rpm riding.