fouls on warmup

[kxt250r]

keep fouling plugs when warming the bike up (watercooled R). both when it idles and when i rev it. after i change the plug its fine and will not foul when running.
do i need to turn the airscrew out some more or..?
cheers


sorry if this has been asked a hundred times before.

[El'Capitan]

what ratio mix are your running in it? sounds like its just running abit rich.

if your running a 32:1 mix, try a 40:1 mix.

[kxt250r]

im running 40:1

[Jason Hall]

What year Is the bike? If It's a 86, with a oval slide carb make sure the slide Is In with the cut away In the rear of the carb. Also you might have the Idle/choke knob turned out/up to far. I've found that a 42 or 45 pilot works best for my bikes, but you might need different jetting In your area. If It's a 86, I would start with setting the air screw at 1 1/2 turns out, then turn the choke/Idle adjuster until It will Idle decent, then fine tune with the air screw.