1998 suzuki DT150 2 stroke carb. the shop cant seem to figure whats wrong. one side of the head is cooling the other is not. it will have a stream coming out of tell tale then it will just stop. the impellor has been done the thermostats are gd, he put a hose in the system and water goes through from thermostats to bottom of head. what could this be. he was pulling the head next to see if there was a restriction then he said powerhead would be next. please please please help. my pockets are emptying fast.