'01 CR250 w/V force

I'm starting to wonder about the stock reed. After a couple of hours of trail riding I start to get a lot of carburetor noise and the engine runs rich at constant throttle settings. Here in western Washington the trails are many times slow and require more finesse than guts. I'm wondering if the reeds are loosing tension as the reed block warms up. I've inspected the reeds when cold and they look like they’re supposed to. It runs very good earlier in the ride when the reed block is cool. Would there be an advantage to going with a V-Force block or just install some carbon reeds in the existing block. I'm running a 15 pilot, H1-76 needle on the second clip and a 410 main. Temperature is running about 50 degrees F., sea level to 3000 ft. elevation.