i know this isnt the right forum to post this in and i apologize but i dont know where else to ask this question and the people in here are very knowledgeable. i just got a used 2001 yz250f .its in really good shape except when you hammer the throttle from an idle the motor will bog and stall. is this a jetting problem and how do i fix it. thanks for the help and i apologize for posting about a bike instead of a quad.

 

Just taking a guess, as I don't personally have any experience with that particualr bike, but it is obvous it is getting too much fuel.

I would start by checking the float specs, if their within specs, then I would go down a couple (2) main jet sizes.
I have experienced this problem with the Rap way back when and it ended up that it was just too dam rich. Went down 2 main jet sizes and was good to go.

 

If Swy's idea doesn't help, you might try to clean out the acceletor pump system. I believe the yzf uses the FCR carb. Take the bowl off and blow all of the passages out going into the accel pump. Also, blow out the passage that runs up to the little brass nozzle in the bell of the carb.

Let us know if it helps.

 

If it bogs off idle it wouldn't be the main jet (unless its grossly off one way or another)clean the carb,reinstall+play with the mixture screw located on the bottom of the carb close to the intake boot.That regulates the fuel flow just off idle.Also like someone else said make sure the accelerator pump is working properly.