Exhaust Exhaust bolts fell off again - tap new threads?

Discussion in '2-Stroke Engines' started by kallsop, Oct 25, 2009.

  1. kallsop

    kallsop Member

    The exhaust bolts have vibrated out about 3 times and the bolts aren't grabbing in the head any more. Anyone tried to tap a larger size thread into the Chinese pot metal and been successful? Or any other suggestions for a PERMANENT repair?

  2. ezdzd

    ezdzd Member

    Yeah, I had a mounting bolt snap off at the at the mount. My easy out then snapped off as well. Ended up drilling it out w/a diamond bit and retapping it to 8mm. Used locktite and haven't had any issues for 150+ miles. With the exhaust bolts keep in mind how they are going to fit onto the muffler or whatever you are using for exhaust. I've also replaced all of my mounting and exhaust/ intake bolts with grade eight bolts that i dremmeled the heads off of. There is a product that slips into a drilled out hole and you actually tap that inserted sleeve so you can keep the existing bolt size. And always use locktite! http://www.timesert.com/html/install.html
    Last edited: Oct 25, 2009
  3. Al.Fisherman

    Al.Fisherman Active Member

    Two choices...well three.

    Drill and tap I'd use a 1/4-20 (drill size #3) maybe even a 5/16-18 (drill size F)...or a 5/16-24 (drill size I ) .or http://www.timesert.com/html/install.html not really good for intake or exhaust due to minimum room to work with. Also with the exhaust you can drill much deeper and won't hit the cylinder...it will go into the head stud holes (if you hit the head stud hole, insert a head stud before you insert the exhaust stud and only tighten till the head stud is hit and back off a turn.. Can't do this with intake.

    Secondly weld and re tap.. I've done one myself and have a picture.

    Third and not necessary, a new jug.

    Will be working on my 4th build. I remove the head studs, intake, exhaust and mounting right out of the box. Replace with grade 5 (grade 8 US is overkill,,,metric 8.8 is about our 5) all thread, and use RED lock tite. To remove RED you need heat and more then these engines get.

    My last build....

    Attached Files:

    Last edited: Oct 26, 2009