Lets see if anyone can save me a headache. I have a ltz 400 with a yoshimura full system exhaust, and a K&N filter. What is the best jetting for that? any input would be useful. thank you

 

Everybody will tell you different jettings . It has to be jetted for where you ride. I live in Phoenix and
If I decide to ride in the mountains my jetting is way off and the bike runs rich but in Phx. it runs fine.
I took my bike in to a bike shop and had it done. Good luck

 

Your going to pull the lid off aswell and run a 165 to a 175, i have the same set up and my quad is sickly fast.

 

well i won't be pulling my lid off. i do about 80 percent of my riding in swamps, mud and wet situations. I just talked to my friend and he said there was no need to re-jet it. I find that hard to believe. but I'm narrowing the jets down. some where between 130 and 140.

 

Without pulling the lid off a re-jet wont help a lot. I would try a 150-155 main and leave the pilot alone. Thats a starting point anyway.

 

not everybody takes their lid off especially if they ride in mud... the lid off things works good but it doesn't take away that much performance to not have it off

 

Instead of totally removing the lid you could drill out the 6 countersunk moldings with a 3/8 drill bit and that would offer more air without compromising your airbox. Unless you are using your z as a submarine. In the winter I run with the lid on with the 6 holes drilled in it and in summer time I ride with the lid off and my jetting is perfect, no need for any adjustments due to temp. change.
later sparx

 

Not everybody takes thier lid off and in this situation I probably wouldn't either. But I would not jet it withourt the lid and then put the lid back on. This WILL hurt performance and it does make a difference.

 

I have an HMF slip-on with 165 main, holes on the air box (k&n), and out a turn on the air screw...

 

Everybody talks about tyhe lid and the main, What about air screw and needle setting?