Hey everyone. I just bought a 2006 DVX 400 yesterday and while I was test driving it today I put it through some hard riding. To me it seemed like the rev limiter was a little low. I've never rode one of these quads but it just seemed to me like it was bouncing off the rev limiter before it was using all its power. I don't know if this is a common problem with these or if it is even a problem at all. The only mods that are done to it are a Yoshimura slip on pipe and a jetted carb that I know of. Any knowledge would be great. Thanks guys!
Have you ever tried removing the airbox lid and seeing if the powerband "cleans" up at all? also make sure your choke is fully functioning. My broke and never knew it until I took it apart, it wouldn't rev fully, similar to your problem. Could also be jetted incorrectly (do you have any info on what it has for jetting). and all else fails, a good carb cleaning never hurts!
The previous owner already took the lid off and I think it has a K&N filter. I took the carb off and cleaned it. Looked at the jets and I remember one of them was a 160. I'm not sure what they came with stock