400ex re-jetting after installing powerlid

[frontman9000]

I just installed a K&N powerlid with a Uni foam filter. I have a DG stage 1 full exhaust system. After installing the powerlid I couldn't believe how much more power it seemed to add and how throaty it sounded! However, I am backfiring much more at low rpms. I was backfiring a little bit before but thought that was mainly due the fact that it hadn't been re-jetted since the winter and thought I was running too rich for summer. Anyway, can I get some advice on jet sizes and what to run with? I still pretty new to all this.

99 400ex

Kenda klaws front and rear
AC Racing pro peg nerfs and full skid
Houser stem
Pro-Taper handlebars
Pro Armor front bumper

[TRFOXX]

Depends on where you live but i have the same set up on my Z400 but on my 400ex i have a IMS lid with Uni with FMF pipe and i have mine set at 155 main with a 40 piolit.

[honda300EXtreme]

yea, to compensate for the increased airflow, you will have to bump up your main jet a size or 2 from where it is now... (assuming you rejetted for the pipe)

and the "backfire" your experincing id just popping on deceleration,, so i would back out your air/fuel screw about a full turn,, if no change then bump up your pilot to a 42

[frontman9000]

Thanks. I live in NJ and I did have carb re-jetted when i had the pipe put on. It has always had a little trouble idling when it first starts and it had been backfiring a little before but now after installing the lid it is definetly does it more and wants to stall more.

[JDMThoughts]

Try these settings, I am a fellow jersey guy and I have no problems with the idle or startup. Very few backfires.

155 main 45 pilot, stock needle, stock clip, and 2 turns out. I am running similiar mods, I live closer to the shore, so I am only a few feet above sea level.