hello so i put new pistons in my 800 and broke in and now it overheats after about 30 min. i checked cyl. heads for leaks when i put it together.the only thing i can think of is air in system or dirty rad. im gonna remove and clean the rad and put in new coolant.what do i mix the coolant at 50/50 or just coolant i wounder if i had to much water mixed?is there something im not thinking of?can someone throw 2 cents my way please thanks guys