GPX 250 strange noise

[craigt]

Im new hear, so first i hope im posting this in the correct area. I have a 2006 250R 54,000 on the clock, ive had it for the past 16 months since 12,000km with no probs, used as my primary transport to work, I stopped using it for a week due to weather, yesterday i took it for a ride and noticed a strange swooshing noise that increases as i accelerate and decreases as i slow down. No mater if i have the clutch in or not the sound is still there. Seems to get worse after approx 1 min of riding when its warmed up then the noise stays constant. I initially thought it was the brakes rubbing the discs as i hadnt used the bike for a week, but it should have stopped by now and also the frequency of the swooshing is too slow for brake disc noise, i counted roughly 4 swooshes /second doing 60kms. Ive checked cables and everything that rotates but no luck yet, starting to think it may be the clutch but i dont have any clutch probs as yet and the noise can be heard with or without the clutch in. Hope someone can shine some light on my strange swooshing noise ( its not a knock or a grind, sounds more like the noise you make when you say "sh")
Thanks
Craig

[Sparks_333]

Check your chain tension. Put the bike up on the centre stand and feel the play in the chain. There should be 0.8-1.2 inches of play. Rotate the wheel and check that the play is consistent throughout. If there are areas where the chain is much looser or tighter, you may be due for a new set of sprockets along with a chain.