I need some advice from any of you who may have already been through this before on an 400EX.

I will be installing a Big Gun complete system, K&N Filter, Outerwear cover, #40 Pilot, #158 Main, and raising the needle 1 groove in the next few days on my 400EX. My question is, to get to the carb to do the rejetting and raise the needle is it easier to remove the gas tank and/or the front/side plastic to be able get to the carb, or can you get to the carb's top/bowl with this left on? I did this work on a 250X a few years ago and remember that it was a real pain to loosen the carb from the intake, and tilt it enough to actually do the work. It appears that the 400EX's carb is much more confined/cramped into the frame than the 250X's was. Any recommendations on the easiest way to accomplish this work?

How does the 158 main and 40 pilot setup sound for the header and K&N combination (leaving the airbox lid off)on an otherwise stock motor? This is the setup that what was recommended by "The Dave" on Off-road.com for his project 400EX. Any thoughts? I usually ride in warm/hot climates at 1-3K feet in elevation.

 

Just take off the side panels then remove the airbox and snorkel. After removing the fuel line (turn your gas off) you can maneuver the carb without having to remove it completely. I've done this about 20 times in the last couple of days. You do not need to remove the gas tank.

 

I JUST WANTED TO LET YOU KNOW THAT MY FRIEND HAS BIG GUN EXHAUST W/ K@N POWER KIT FILTER AND JET'S THIS BIKE IS LOUD AND FAST. I HAVE A D@G EXHAUST WITH POWER UP KIT AND HIS BIKE IS FASTERBY A GOOD BIKE LENTH. WELL GOTTA GO

 

Hey AZ....

My buddy has a Big Gun,K&N and is running a 170!! With no air box. The exhaust and air filter allow the use of the 170 main jet. You need to remove the air box so the engine can breath. He also installed the high rev CDI box and now he's the one everone is trying to catch, no joke.

Dave in Oklahoma, '99 400ex

 

remove the air box?? or just the lid??? lol

 

Just the lid.

 

coool!!!!!!!!!!! thanks ccarpel!!!!!!!

 

I RIDE IN REALLY DUSTY ENVIRONMENT AND WAS WONDERIN IF THE K&N WILL HOLD UP WITH THE AIRBOX LID OFF AND HOW OFTEN WOULD YOU HAVE TO CLEAN IT? IS IT ANY WORSE THAN NORMAL?

 

Make sure that you buy the K&N Precharger sock, it'll handle the really dusty conditions that you mention, and will extend the periods between cleanings.