05 400 Ex missing on acceleration...

[vpofthedrc]

I bought my 05 400 EX back in January, and am just now really getting it out. Rode pretty heavy last weekend, and it seemed to have a slight miss when I accelerated. There are no mods done, and I haven't even done the first maintenance to it yet.

[journeyman]

how many hours you got on it thus far....when i bought my 05 she ran awesome until i had about 15 or 20 hours on it then started to loose a lil umf!I tokk it in and got the 1st service done and shes got more umf then she did when i bought it...i would say get the service done and get that breaki in oil out of there...that should do it!!

[400ex27]

i heard a rumor that sometimes the plug gets dirty from the
rings not being seated during breakin, but again that was a
rumor from a semi reliable source.