Whirring Sound CRF250R 2006

I have a 2006 CRF250R purchased used in Dec 2011. I ride occasionally and the bike has always made a whirring noise that other people notice too. The bike has made the noise for as long as I have owned it but it seems to be getting louder. I have set the valve shims twice and inspected all that you can see with the valve cover off. Nothing unusual and the cam chain tensioner works properly. Bike runs well, starts fine and has good compression. It makes the noise at idle and when you rev it up. Makes same noise with clutch lever pulled or released.

Any thoughts or experience with whirring noise?

I have a 2006 CRF250R purchased used in Dec 2011. I ride occasionally and the bike has always made a whirring noise that other people notice too. The bike has made the noise for as long as I have owned it but it seems to be getting louder. I have set the valve shims twice and inspected all that you can see with the valve cover off. Nothing unusual and the cam chain tensioner works properly. Bike runs well, starts fine and has good compression. It makes the noise at idle and when you rev it up. Makes same noise with clutch lever pulled or released.

Any thoughts or experience with whirring noise?

check your camshaft bearings. If they were ever starved of oil they will make a whining noise, the noise will go up and down with rpm's. Product of putting oil filter in backwards.

10:4, I will inspect or change cam bearings when in it for valve shimming soon. Thanks!

Any other thoughts out there????????

It could be your carb slide rattling

Just pulled it down to set valves and the cam bearing next to the timing chain has a bad spot in it. Bearing on other end is fine. Time for a new cam because sprocket is pressed on captivating the bearing next to it. Thanks for the help!

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