need a round about jettting spec

["THE ShoP"]

my buddie has a 03 z-400 just got a full HMF pipe an K&N air filter anyone know what jet would be a good jet to start with?

[raptor684]

He might be able to run a 135 main, I got a z with a slip on and got the stock 130 main jet in

["THE ShoP"]

if you have a slipon you shout def bump your jet up alitte

Anyone out there have the same set up as my buddies Z?

[z400ACDC]

Mikuni 180 with the lid off or a couple of 1.5 inch holes cut in it.

[bellzbub]

hmf should have sent jetting specs with it. if not call them and ask.

[RATPACK Z400]

Tell him to start with 148 and go from there I have slip-on, uni-airfilter,revbox,and im at 152 not sure cause iv,e changed so many times to get right .One thing Ive learned was get dyna-jet kit it comes with new needle and all jets and directions you,ll need and is easy to follow, cause you need to jet for altitude and mods.a slip-on with no jet change Iv,e never heard of.You need to jet with mods period .If you dont will run lean and burn motor up!

[haulazz400]

so even with a slip on pipe you should rejet also?

[z400ACDC]

If you want to get the most "bang for your buck" you need to modify your airbox lid so the engine can breath better. The slipon helps get the air out of the engine faster, but it does not help speed up the air on the intake side. Cut the lid(or take it off) turn the airscrew out to 3 turn, and put in a 180 mikuni jet and you will notice a big low to midrange gain.

[haulazz400]

i already have it jetted for no lid with a k&n filter but it was boggy when i was stabbing the throttle with the new pipe on. and i couldnt get it to run good by just adjusting the air screw

[RATPACK Z400]

Did you use jet kit ? theres a new needle that comes with kit you need to have.and whats the size jet now ,what year is it ?I think they changed carbs in 05 model not sure though .mines a 03 and just slip-on and filter and altitude mine run around 152 its going to be different at different altitudes as well .If you were in maryland I,d stop by and help !

[haulazz400]

no i didnt use a jet kit, just main jets. its an 05 , i believe its a 143.5 main right now. and im at some where around 4000 feet in cny

[z400ACDC]

Originally posted by haulazz400
no i didnt use a jet kit, just main jets. its an 05 , i believe its a 143.5 main right now. and im at some where around 4000 feet in cny
Are you having a hard time understanding what I am saying? A 143 main is WAY lean without a lid!!!!!!!!! You will burn a hole in the piston like that. I have been riding and racing for 30 years and have rejetted many carbs. Be careful, a busted piston can get in your pocket fast!

[indyZrider]

acdc : i have an hmf slip on with an ehs lid and the snorkel removed and my 155 DJ was too big. a 180 mikuni is equal to about a 192-195 dj. i just dropped mine down to a 150 DJ to try and lean it out a little. you must go through polugs like crazy with a 180 mikuni. the only guys running 180's are the ones with cams and bb kits that havent gotten a better carb yet.

[z400ACDC]

Originally posted by indyZrider
acdc : i have an hmf slip on with an ehs lid and the snorkel removed and my 155 DJ was too big. a 180 mikuni is equal to about a 192-195 dj. i just dropped mine down to a 150 DJ to try and lean it out a little. you must go through polugs like crazy with a 180 mikuni. the only guys running 180's are the ones with cams and bb kits that havent gotten a better carb yet.
My Z is jetted fine. If I remember right, a 150 Dyno Jet is= to a 180 mikuni. Jeremiah Jones gave me a complete DJ kit,but most of the time I use mikuni's. I have jetted several Z's and a 175-185 mikuni will work best with a lid mod. I'm done, out!

[indyZrider]

here is the conversion chart:


Mikuni Dynojet
140 149.3
___ 150
142.5 152.0
145 154.7
___ 155
147.5 157.3
150 160
152.5 162.7
___ 165
155 165.3
157.5 168.0
___ 170
160 170.7
162.5 173.3
___ 175
165 176.0
167.5 178.7
___ 180
170 181.3
172.5 184.0
___ 185
175 186.7
177.5 189.3
___ 190
180 192.0
182.5 194.7
___ 195
185 197.3
187.5 200
190 202.7

[z400ACDC]

All I can tell you is that we are jetting 175-180 with a pipe and no lid. Maybe it's the KY air! They run great with a nice tan plug.

[cataway]

the pipe your using has some thing to do with the jetting,as well
i suspect your not using a spark arrester, right?