stripped head bolts

Discussion in '2-Stroke Engines' started by nadroj, Sep 9, 2009.

  1. nadroj

    nadroj Member

    I stripped the hole it goes into on the lower end what should i do?

  2. Al.Fisherman

    Al.Fisherman Active Member

    I myself would drill it out and tap a larger size (either metric or SAE). The use of a Heli Coil or the like should be used as a last resort as you need to drill a much larger hole for the Heli Coil itself. Don't get me wrong but Heli Coils have their place and time. Which hole exactly did you pull the threads out of, you say "into on the lower end" more specific...Cylinder stud, case bolt??????
    If the bolt you are talking about is the #6 bolt at the bottom of the case, directly below the coil/magnet, I'd drill all the way through with any of the following drills...6mm, 15/64 or a "B" drill bit and insert a bolt long enough to install a locking nut on the other side. If this is the's a piece of cake.
    Last edited: Sep 9, 2009
  3. nadroj

    nadroj Member

    its a cylinder stud
  4. spad4me

    spad4me Member

    Buy a larger tap and carefully re tap the hole just as AL Fisherman says.
  5. Al.Fisherman

    Al.Fisherman Active Member

    ( This is for a 8mm stud ) A 9 1.25 drill size of "N" or 5/16 might work...Test on a cull piece of material first. If not then go to a 3/8 16 using a 5/16 drill bit.

    Arranged from smallest to largest in order

    9 X 1.25 7.8mm (drill size) or "N or" 5/16

    3/8 X 16 5/16"

    9 X 1 "O" or 5/16

    10 X 1.25 8.5mm or "Q"

    Both the jug and head will need to be drilled out.
    Last edited: Sep 9, 2009
  6. Al.Fisherman

    Al.Fisherman Active Member

    For a 6mm stud.....

    6 X 1---------5mm or #9

    1/4 X 20------#7

    6 X .75--------5.25mm or #5

    1/4 X 28-------#3

    6 X .5----------5.5mm or #3 or 13/64

    7 X 1-----------6mm or 15/64 or "B"

    7 X .75---------6.25mm "D"

    5/16 X 18-------"F"

    8 X 1.25---------6.8mm "H"

    Last edited: Sep 9, 2009