I have a 02 400ex with white bros exhaust and k and n filter it has stock jets in it and I'm getting a lot of popping and cracking I live at low elevation in ft Bragg nc so that isn't a issue what size jets should I go to I'm thinking a 42 and 155 I don't want to have to keep taking my carb off and on to change them so I'm trying to get it right the firsts time what do y'all think is that a good choice or should I go with something different I also want a CID and timing chain kit for it will that make a difference let me hear y'all's thoughts

 

Some one has to have some advice

 

Its all trial and error with jetting. I think you are in the right area of jet size 42 - 155. A cdi does not really do much for a ex especially with a stock motor. The ex makes makes most of its power down low and not at a higher rpm. The cam chain will give you no performance gains.

 

Ok thanks hopefully I can get them changed over this week I prob want full with the Cdi then any other advice on getting more power

 

Some other easy things you can do are remove the header and grind down the welds by the flanges and vent or prop up the air box lid.