I had been told about a common problem with 2007 model WR250F’s and WR450F’s but it didn’t occur to me to check for it when I got the bike, now, did it? I’m so stupid sometimes!
The problem is that the air filter cage comes from factory with a hole down the middle of the stalk, which is a hangover in design from the previous models which had a screw to mount them through the middle. Since the new model has a spring clip, the hole is not only not required, but if it is there it is basically a hole through the air filter directly into the intake. Now, while the liklihood of substantial amounts of dust getting in is very small, this is a potential problem and Yamaha will replace or fix this cage under warranty.
If you have a 2007 WRF, check your air filter cages. If they have a hole down the middle, take them to a dealer and get the cage replaced or repaired.
I used a 1/2 inch bolt with about an inch of thread, screwed it into the hole in the cage. Fixed.
