head bolts torgue weight

Discussion in '2-Stroke Engines' started by murduk0420, Mar 26, 2010.

  1. murduk0420

    murduk0420 New Member

    How much torgue weight should be on the head bolts?:detective:

  2. Gh0stRider

    Gh0stRider Banned

    100-144 in/oz

    I use a 1/4" drive torque wrench. They don't need much. Replace the acorn nuts with metric bolts, use blue loctite on both ends of the studs.

    As the engine wams up and expands, the pressure on the studs increases. Overtighten them and they might pop when the engine is hot.
  3. chefdouglas

    chefdouglas Member

    Great point, thanks I didn't think about heat expansion before. Blue loctite is only good to 300 degrees f is that enough? I know a lot of people don't use the red on bikes but would this be an exception?
  4. Gh0stRider

    Gh0stRider Banned

    I don't think the head or crankcase temp should exceed 300F. If it is, you're most likely running too lean. The head on mine tops out at around 275F running WFO for a while. Puttering around 20mph it only reads in the low 200's. The blue stuff is service removable - the red stuff is meant to be permanent.

    The jugs on other air cooled engines also have pretty low torque values for the same reason (expansion). Many people over torque the head studs and pull them right out of the crankcase because they torque them by feel. A small in/oz torque wrench and a light hand is mandatory when working on these little engines.