Motorcycle Repair: IT 490, stroke oil, carby

Question
WHEN I RIDE FOR 30 MINUTES MY BIKE STOPS AND THE PLUG IS FOULED UP. I PUT A NEW PLUG IN AND IT GOES GREAT FOR ANOTHER 30 MIN IT HAS BEEN REBUILT BUT THE CARBY HAS NOT WHAT DO YOU THINK

Answer
Mike,

The 490 is a beast and most of them
do foul plugs occasionally. The problem
seems to be in the head design.

-Other possibilities are a plugged or
oily air filter.

-Bad carb reeds

-Plugged transmission vent.

-Right side crank seal sucking oil into engine.

-worn carb needle.

-bad or faulty carb float valve

-do you pre-mix fuel 32:1 with good two stroke oil?

-use NGK plugs.