i have been doing alot of modifications and never had a problem with it cutting from quarter throttle to wide open It started with my last mod putting the 400 ex boot in place of the stock I also have a really big k&n 5 by 8 inches I have ran through the jeting and tuned my exhaust with the disces cause I have a ct pipe and nothing has made the cutting out any better the only thing I could think of is maybe the caburator cant keep up anymore with the mods any Ideas would be great Im new at this fourm so Im trying it out thanks.

 

Are you just still lean on the bottom? Bigger pilot jet???? Raise the needle, or get a different shaped needle????

 

I have gone from a 25 pilot jet to a 40 and that seems to do pretty good and 195 on the main on the mixture screw I am one turn out and thats supposed to be about perfect so I ruled that out but maybe the ct needle needs adjusted I thought that was for fine tuning I didnt think it could have that much impact. I have played with the jetting all across the board and every since I added the new intake boot I cant get rid of the miss but when it gets through the miss it launches like a bullet can the intake be to free flowing

 

I would try the air fuel mixture screw a little more out.When I changed my 38mm Mik to a 42 smooth bore I had the same thing going on.I went throgh the same steps as you did,pilot,main,needle.Then I called a few shops and they told me the air fuel screw wwas not right,it was close but not right.I turned it out about a quarter turn more and it worked great,no hesitation.Try that ,good luck.

 

that 400ex boot,
it is probly keeping it from gettin air.
cause it isnt made to fit the kfx 400.
my old honda 300ex started cuttin out when i messed with the intake.
id put the kfx boot on there.

 

can u start in by the button because mine did that bacause the ffuse burnt out

 

need to have your valves check this is aways the case the ct pipe adds more exhuast release and the valves over time will losen and not lift right you might nee to shim or buy new.