1996 yz125 problem

[yz80nbeast]

my brother has a yz125 and we had the top end done because we bout it not running and it runs now but i start it ride it and then it boggs down and it will not start after about 5 mins and the spark plug is barely fouled but if i put a new one in it will start and do the same thing but i can let it sit for an hour and it will start and do the same thing? plase help

 

[_JOE_]

Clean the carb.

 

[matt_12345]

id say u def. have carbeurator problems.