I have an '06 Z400 and yesterday while riding I decided to take the air box lid off but when I did the engine ran like crap. It would fall on its face and spit and sputter. Has anyone ever had this problem before. The machine is completely stock.

 

Its running lean. Need to re-jet it

 

agreed suzuki doug, taking lid off lets alot mor air in and a rejet would b necessary.

 

Yeah I had to do that when I took my lid off I went up to like a 13 then with the pipe I put a 147 on....

 

A lot of people believe that removing the lid will give you gains getting more air in. This will only improve the performance if you re-jet to increase the fuel flow or if you have EFI it will compensate itself. Since your bike is stock and no pipe has been added, there is no reason for you to remove the lid on your bike except to clean your filter.

 

If you remove the lid and rejet (~150 main) there is a nice power gain. This was the first mod I did, it was well worth it.

 

I have to agree with this. Just re-jetting I had huge gains. Check out this dyno sheet of mine.

Here is the link and you can see what just jetting and taking the lid off will do for you.

 

how hard is it to change the jets, and is there a step by step tutorials for dumb@$$es like me to follow?

 

Check your PM's I will send you a link for a step by step process.

 

Thanks everyone for your input.

SuzukiDoug- can you please send me that link for the step by step process on changing jets. Thanks