Full system Rejetting

[yellowWB400ex]

I just bought a WB R4 full system and run it with air box lid off and a dealer told me I didnt need to rejet it, it would just run a little richer. I want to know if this is correct. It just pops a little when u hammer on her and then let off other than that it livened my quad up a lot :p

[LTZ400rider]

are you sure he said that. if he did hes a dumbass. u should rejet with a full system, especially with the lid off u will be running lean as hell. u should be able to see ur head pipe glowing red

[400-416EX]

You are running way to lean with the setup you listed. I have a brand new 400ex dynojet kit for sale for 45.00 if your interested.

[cals400ex]

what elevation your live at? what temps you ride in? we can get you close enough so you should only need to buy 1 or 2 mainjets and 1 pilot jet. yes, you are running lean and it should run much much better after rejetting. you will be lean especially with the air box lid off. that makes a pretty big difference when it comes to jetting.