Jetting question

[jaywoodsrider]

The spark plug on my quad is black, does this mean that i need to change the jetting. My 300 has a fmf full system with a k&n filter.

[zephead400ex]

Your too rich. But cant suggest what to use, not familiar with jetting a 300ex. But you are too rich.

[hondarider2006]

You are running to running to rich. What size MJ are you running right now?

[cals400ex]

is it black when trying to start it? or is it black at idle, 1/2 throttle, or full throttle?

[jaywoodsrider]

It still has the 122 main jet and the exhaust is black when i start it up.

[quadrider400]

Take off the air box lid if you have not done so yet this will allow for more air in .... you opened up the exhaust and the intake a bit but I would go for max air before you rejet....

[cals400ex]

i bet your just richening up the mixture when trying to start it makeing a black plug. a stock mainjet (122) won't be too big when you have an aftermaket full exhaust on your bike.