I just picked up my White Bros. Pro-Meg exhaust and K&N Power Kit for my 400. Would I be better off to remove the stock airbox lid or make 6 one inch holes like I've heard alot of people talking about? One person said to remove the stocker so when you wash the quad no water will get in. Also if I make the holes, what is the best way to do this so it doesn't look "homemade"? I would appreciate any suggestions.

 

Ruffridaz,

If you modify your quad in the way you mentioned, don't forget to rejet to allow for the additional airflow. K&N and Dynojet have a very complete rejet kit that costs about $45-$50. You don't want a lean running quad!!

Lightninn

 

I measured out six evenly spaced one inch holes, three on each side going lengthwise. I cut them out with a drill and one inch holesaw bit, then installed airbox vents that I bought from White Bros. They just pop right in and include foam inserts that I sprayed with filter oil to help keep out some dirt and water. If a person didn't know what the lid looked like, they would think this setup was just stock.

 

How much do the air box vents cost and does it make that much of a dirrerence in the performance, i also have a K&N Power Kit for my 400 and I was thinking about the mods.

~~Mike


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~~Mike

'99 400EX, FMF Power Core IV, Works Triple Rate Shocks, AC Nerfs, K&N Power kit, Renthal Bars, etc...

 

You might-as-well just pull the airbox lid off, that way when you wash it you can put the stock lid on. Also you may want to look into a motoforce airbox lid which has a notch with a lip to the side of the filter so so water doesn't hit the filter if splashed up a little.

Good Luck,

Sickman

 

Airbox vents only cost around $5.00 for a pack of six. Putting about 6-8 vent in the lid and rejetting will make a difference in power. More air + more fuel = more power. I don't recommend just taking the lid off, first, it will reduce your waterproofing abilities to zero and second, the bike will run worse with the lid removed than with it on, the engine needs the vacuum that the lid (even with holes in it) produces. I have seen dyno result that show about a two HP loss on a stock 400EX with lid removed compared to one with lid attached.

 

I HOPE YOUR 400 EX SCREAMS WHEN YOU GET DONE! THEN WE CAN BUMP THEM OFF !!!