400 EX Hiccups

[indyZrider]

im a ZUKI guy but the wife rides a 400ex and she now wants a pipe and stuff like that done. i adjusted the valves per the honda service manual and i would like to start tinkering with the intake exhaust and jetting. this thing is bone stock. my question is do these come a little rich or lean from the factory? it seems weird whenever i hold the throttle steady like at 1/4 or 1/2 while its sitting in the garage it kinda hiccups like its backfiring through the carb and air filter and wants to die. is this normal? in the Z400's whenever you intake and pipe them you normally have to bump up the pilot jet. is this the case with the 400ex as well? also what seems to be a good pipe thats not too loud for the 400ex. my buddy says the fmf pipe is a good match with honda like yoshimura is to suzuki but i think it might be too loud for the wife's desires. thanks for any info or help in advance.....

[drew416ex]

Normally the 400 is a little lean from the factory. 99% of the riders on here run a 42 pilot, as far as a main you will have to play with it. Probably a 150-155. When you get it jetted right it should stop the hiccup. The fmf isnt bad. I had a white brothers e-series on mine for a while and liked it.

[big95xj]

Make sure to check the boot that goes from the carb to the engine for breaks or cracks. I know they will hiccup like that at low rpms with ti broken but not sure about 1/4 to 1/2....

[indyZrider]

is the 42 pilot one size up from the stock one? and thanks for the suggestions and info....

[sprayedgt]

It's 2 sizes up.

[f4istunna]

my wifes used to have the same hiccup about 1/8 to quarter throttle and died if you stab the throttle. I bumped the pilot up to a 42 if i rememver right, and it cleared right up. I kept thinking it was the needle since it started pretty easy and was only doing it when you hit the gas but bigger pilot took care of it.

[Mustangous]

Mine does it too when cold and trying to warm it up. I have stock jetting. I am gonna try playing with the pilot eventually.

[indyZrider]

thanks for all the help, i appreciate it!

[hdlstns]

I have a 02 400EX (completely stock) and I am at the same point you are with yours. I am adding performance mods slowly... I just put on a complete Noleen exhaust system. I haven't jetted it yet (waiting on shipping) but man what a difference in power! It really comes alive with the extra flow. Of course it was running just a little lean when I test rode it. Wonder what it will do when I add a little more fuel to that air?!

I have also noticed the hiccup at 1/4 throttle...I thought it was missing at first. I was worried my coil or CDI was getting ready to go. I will be jetting it to 42pj as soon as my kit comes in.