I posted this in the 250f forum but thought maybe you guys would have some input as well being that the forks are the same. I posted this in the suspension forum and got no feedback any help is much appreciated. I own a 2004 yz250f. I went to the track two weeks ago and I started hearing a hissing noise like air escaping from the front forks of my bike when landing off of the bigger jumps. I noticed a little bit of dust build up at the bottom of the fork so I thought maybe the fork seals are leaking a little. Turns out one fork tube was seeping, but not enough to get by the dust seal. Anyway I put new fork seals in . No leaks, but still getting the same noise. I then started thinking maybe its the fuel cap breather hose, but onlookers told me they could hear the noise too!!! No way that breather hose is releasing that much pressure plus I have never heard the noise before until recently. It's got to be the forks. It makes me cringe when i hear the noise. Any ideas on what this could be. Please help!