Z400 Jetting

[thebushman]

Have an '04 Z400... bought me A Yoshimura S/S full system. Have a K&N coming.....Bought a Dyno jet to go with it. My question is where should I start on the jets. What size does everybody start with? I'll say thanks in advance. Also am I gonna notice a big difference in performance? Thanks, George

[huffdaddy_400EX]

The instructions for the Yoshi should tell you where to start based on your elevation. Just following those instaructions and you'll be fine.

For me, I have a Yoshi full, K&N, lid off and I'm running a 155 main. You'll need to also adjust your fuel screw, located at the bottom of the carb. It's a pain to get to because you have to remove the plug that is there.

[Dalex]

Here is what I found on the Yoshimura website:

Instructions may have incorrect recommended jet size

LTZ400 Slip On Exhaust:


217253, 2175600

Jetting for Stock Airbox with no modifications:
Stock main jet #125.0

Jetting with airbox snorkel cover removed:
Mikuni main jet #145.0

Jetting with airbox lid & snorkel cover removed:
Mikuni main jet #152.5


LTZ400 Full System Exhaust:

2175157, 2175500

Jetting for Stock Airbox with no modifications:
Mikuni main jet #122.5

Jetting with airbox snorkel cover removed:
Mikuni main jet #145.0

Jetting with airbox lid & snorkel cover removed:
Mikuni main jet #150.0

[was123]

Originally posted by Dalex
Here is what I found on the Yoshimura website:

Instructions may have incorrect recommended jet size



also that info states mikuni jet sizes and not dynojet sizes and there is a diffrence.....

[Dalex]

that is true

[LTR450_#67]

Here go to this link----->Mikuni/Dynojet cross reference (http://www.vmaxoutlaw.com/tech/dyno-mikuni.htm)

hope this helps

[thebushman]

Thanks for the info. I think I got it...thebushman :D