2 stroke question 250r wet plug

[RobbRacer]

i just put my motor back in after taking it out to powdercoat the frame and i didn't do anything to it or the carb. now when i start it up it will run for a little bit but then it bogs down when i give it throttle and then dies. i take out the plug and it is very wet with premix. i dry it and put it back in and the same thing happens again. i took the carb apart and cleaned it very good and put it back on and the same thing happens again. i put a gas tank on it and put fresh fuel in it but i noticed when i drained the old gas that there was some sand in the tank. so i am thinking that is the problem. my manual says that is the plug is wet that it could be caused by the starter valve being stuck open but it doesn't say where the starter valve is or have a labeled picure. i think that the sand may have gotten into the carb and is plugging some lines or keeping some jets or needles from closing all the way but if someone else has had this problem and figured out what was the right way to fix it let me know please.
i am gonna clean the tank and pet cock and carb again and see if i get any better results.
thanks
robbracer

[AndrewRRR]

That sucks, I hope you had a fuel filter on your fuel line!
Take the carb apart, douche it with carb cleaner and blow it out with compressed air (all the jets, bleed holes,etc). You should take off your gas tank and dissassemble the petcock, and clean them both also. If you had a fuel filter on, change it. If you didn't PUT ONE ON!!!
One thing you can check right now is pull the fuel line off the carb and turn on the petcock. If the fuel flows out good then the problem is in your carb (still clean the sand out of the tank and petcock though). If it is just a trickle or not comming out at all the problem is probably in your petcock or more likely the fuel pickup in the tank (but again, still clean out your carb good). If you had a fuel filter it's probably clogged.
Hopefully sand didn't make it into the motor.