Spark Areester/IDLE

[EXerHonda400]

I have a WB R4 Silencer on my 400EX, and when it is idleing it is going up and down with the RPMS ( it speeds up then slows down almost to the point of shutting off then gets to normal again). My spark arrestor (which is just a metal screen) has some carbon build up on it and is pretty black. Would that have any effect on my idleing??

Any thing will be appreciated,


Thank You

[JOEX]

It might, make sure you have a good spark plug too as well as good gas.

You might need to fine tune the jetting.

Joe