jetting help?

[cjmadison9]

just installed a 434 bore kit on my kfx400, it starts and idles fine, and i got a jetting kit for it, when i asselerate it gets to about half throttle and it starts cutting out, its not cutting out bad but still needs to be fixed, it has a 130 jet in right now, what would yous suggest on jet size? i did try adjusting the air/fuel mixture screw but it wasnt helping, thanks for any feedback and help!

[juice420]

A 130 is wayyyyy to small, I'm surprised it even runs at all with a 130 and a bbk. I run a 150 and I don't even have a bbk, just a slip on K&N intake and a powerlid. If I were you i would get a FCR39 carb. I bet you would get a ton more power with it, the stock carb is holding the bike back with that bbk. And adjusting the fuel screw isn't going to do anything it's just for minor adjustment in the low RPM's.

[jemerick05]

I just installed a Cylinder works BBK 434cc on my Z400 and before i did that i had a 160 MJ and it was running way to rich with the BBK. I took it to the dyno and when it was all said and done I ended up with a 150MJ and gained 9hp. I have a FMF slipon and twin air filter, those are the only mods done to the motor.

[juice420]

Originally posted by jemerick05
I just installed a Cylinder works BBK 434cc on my Z400 and before i did that i had a 160 MJ and it was running way to rich with the BBK. I took it to the dyno and when it was all said and done I ended up with a 150MJ and gained 9hp. I have a FMF slipon and twin air filter, those are the only mods done to the motor.
So let me get this straight, you have a bbk a slip on and an aftermarket air filter and your only running a 150? Is that a DynoJet 150?? What about the pilot jet and needle?

[jemerick05]

yeah i have a BBK running a Dynojet 150 MJ and 17.5 PJ. Everyone I talk to says that those are way to small, but it runs great. the needle i think is on the third slot from the top.

[juice420]

Originally posted by jemerick05
yeah i have a BBK running a Dynojet 150 MJ and 17.5 PJ. Everyone I talk to says that those are way to small, but it runs great. the needle i think is on the third slot from the top.
Do you check your plug regularly that thing has got to be running lean. 17.5 pilot? Do you mean 27.5?

[cjmadison9]

yeah, ive bin tols to fun a 150mj, air/fuel 3 1/2 turns out, and the needle 3rd slot down ao that sounds pretty close to what your running, one thing you gotta remember is that different brands have different size jets, hense the fact you gotta have a needle and a jet of the same brand, so a 150 dynojet might be larger or smaller than a 150 jet of another brand, that might be why is sound like your runnig so lean shen maybe your not....