The rule of thumb is around .003" intake and around .005" exaust. I don't know the spec off-hand but there may be a sticker tellin' you what it is on the bike, usually under the seat on older bikes. If not any decent Yamaha dealer can tell ya the spec. For real you should get the exact spec and only check it with the engine stone cold like after it has been sittin' overnight. A little loose is ok but tight isn't good and can cause damage.