I saw this in Dirt Wheels, K&N ATV kit has filter and jet kit. I think they use the Dynojet kit? Is there any difference in the jet kits available, are all necessary jets included. do I need to buy bowl gaskets for the swap? Can I leave the carb on the bike? My quad is stock and has a flat power band over 5-6 grand up. It just looses its hard pull. Is that due to lean jetting, airbox, or exhaust? Thanks guys.

 

with the k&n kit you get a filter.outterwear,and various size jets to try.you get different jets because some guys use a stock exhuast others do not.others put holes in the air box some do not.everything makes a difference when jetting.with a stock 400ex and a K&N filter only no holes in box and no other mods go with a 155 main and a 40 pilot. youll tell a difference right away .if you want more ,go with a 160 main and lift the air box lid in front,and put the front 2 clips under the lid and secure the other 4 clips this will let more air in.and when you need to go thru deeper water you can put the lid back down.no you dont need another gasket.and yes youll have to remove the carb ,its fairly simple

 

I fall in the same boat. I have no experience with the jetting and the patience of testing. i am looking at getting the kit soon and a white brother pipe. I think i"ll use the uni vents on my airbox. Then find someone to do the carb. Last time on my 300ex I had a uni and jetted,airboxed and there was no power change. Anyone that has done this to a 400ex please come forward and tell me what jetting is best and how many discs are used on the pipe for dune climbing? it's all helpfull. Thanks

 

I've put a K & N power kit stage 1 on my 400EX and it says to put the main number DJ142 in it with the needle provided on groove number 3. It doesn't however mention anything about a "pilot". Could you please tell me what a "40 pilot" is. Thank You.

www.geocities.com/hulioni

 

I'VE GOT A 400EX AND I'VE REMOVED THE QUIET CORE SILENCER FROM THE MUFFLER( A PRETTY EASY MOD),I'VE CUT A 2" X 3" HOLE IN THE BACK OF THE AIRBOX LID AND I HAD TO GO UP TO A 158 ON THE MAIN(148 IS STOCK). I HAVEN'T CHANGED THE PILOT YET, BUT I NEED TO. THE PILOT JET HELPS IN STARTING THE QUAD. MINE IS HARD TO START IN COLDR WEATHER.SINCE I'VE MADE THESE CHANGES, IT'S NOT LIKE RIDING THE SAME QUAD. ON A DYNO RUN I' SEEN THIS SETUP AND IT PUTS OUT 32.5 HP VERSES 27 OR 28 STOCK. YOU'LL DEFINETLY SEE AND FEEL A DIFFERENCE (A HUGE DIFFERENCE). I RUN THE STOCK AIR FILTER BECAUSE ITS AS VERY GOOD STOCK FILTER. THESE MODS COST ME ABOUT $30.00 BECAUSE I HAD TO BUY 3 DIFFERENT JETS BEFORE I GOT THE CARB RIGHT. GOOD LUCK!