I am in the middle of adjusting the valves on my 400 and I saw that the snorkel has a flange around the edge. will it be okay to trim that out, and if it is will it flow enough more air that i will have to rejet? I don't think it will actually flow that much more, but I thought better safe than sorry. thanx for the help. ride hard, jon

 

when I put a K&N air filter ($25) on my 400EX I trimmed both ends of the air snorkel...

it's easy to remove the gas tank... then just disconnect the snorkel and pull it out...

I took a hack-saw and cut 1/4" off the high end to get rid of the smaller oval shaped opening; then I cut out the entire lenght of the bottom end that protrudes into the air box... this portion blocked a significant part of the air filter itself

next, I removed the spark-arrestor screen on the end cap of the silencer (again with a hack-saw) and upped the carberator's main jet size from the stock 148 to a 150 - $4

so, for less than $30 and about an hours worth of work, I have increased my air / fuel / and exhaust flow... not substantially, but a slight improvement non-the-less, while being able to still do water-crossings with confidence (as opposed to removing the air box lid and snorkel) and without increasing the dB level of my exhaust.

PS. if you're planning on taking it to the track, the dunes, or any-other adventure for a day when you think you want the most power you can get out of it, just remove the air box lid and the silencer end cap completely... it only takes a minute, and you WILL notice a difference in power... but I don't ride around like that all the time, it's just too loud and my filter it too prone to dirt and water... besides, if you want to run like that all the time, you should remove the air snorkel too, and upsize the main jet to a 152 or more (do a plug test to make sure)