I am running the stock plug. Mickey dunlop said to use a DP9EA in and artical tips and tricks for a 400ex he said it is a colder plug and will make the engine run cooler has any body tried this. Also my plug was black still running great but does that mean I am running lean or to rich? I have and e-series pipe K&n jet kit. This is a 2002 400ex .

 

Well thats a good plug to use and my brother is running the same one in his 400ex. When the plug is black that means it is running rich. My recon was the same way it was running rich but still worked great but when I rejetted it is normal now.

 

i thought the stock plug was dpr8z. then the colder version for the 400ex is dpr9z. my 300 4x4 uses a dpr8ea and the colder version of that plug is dpr8ea. what brand is the dp9ea? is this ngk? just wondering because my owners manual says nothing about the dp9ea as the colder plug but it says the cold plug is dpr9z in a 400ex.

 

In tips and tricks they say DP9ea that is from Mickey Dunlop

 

where is tips and tricks at?

 

I t was and artical written by top mechanics and riders in the atv world on what tips they do to the 400 ex I can fax it to you. The issue it was in Feb 2002 4 wheel atv