I am having problems with my 88 250r(Port and polish, keihin pwk 39mm, fmf pipe and silencer) It runs terrible and when I let off the throttle it bogs down and dies. does anyone have any ideas as to what it could be. I have been trying to get the floats set right!!

 

Check airscrew, I had the same problems with a 38mm carb on mine. I think it is too rich!

 

will it idle by itself?? try setting your throttle cable so it idles nice

 

Try moving the needle down(moving the clip up) in the carberator one clip at a time until it clears up.