Head bolt Predicament...

Discussion in '2-Stroke Engines' started by colemanbales, Mar 4, 2014.

  1. colemanbales

    colemanbales New Member

    Hey guys, so i was doing some work on my bike trying to torque the head bolts (i guess thats what you would call them?) to 120 in/lbs. Now, i had some trouble finding a good method to go about doing this, so i ended up putting two nuts on the bolt (as seen in the picture below) and tightening them together in order to have something to turn the bolt. I used this method on all of the bolts, and then finished up, and reassembled the engine. I went to see if the bike would turn over, and it seemed as if the engine had seized up entirely on me. I removed the head and could see that in fact the piston would not move up or down, when i tried to roll the bike with the clutch out, the back wheel simply would not roll (it would roll if the clutch was pulled in). I thought this was particularly strange, because when i had the head off trying to torque the bolts, the piston would move up and down just fine. it was only once they where all torqued down (and left overnight) that the engine would not move. To make matters worse, I accidentally stripped some of the bolts trying to remove them! The bolts are also lock tighted in. Could someone please tell me how they would go about dealing with this? I am worried for the sake of my engine.
    bike head bolts.jpg

  2. Bzura

    Bzura Member

    Just speculating, but maybe a nut or something fell in & got jammed inside the crankcase.

    I'd take the drive gear cover off (the one with the clutch arm) and get an appropriate size ratchet to try and turn the sprocket to turn the crank in both directions.

    The head bolts would not interfere with anything, but if they're stripped they should be replaced.

    Sorry if that's not enough help. I've never experienced that before.
  3. Purple Haze

    Purple Haze Active Member

    It's possible that you distorted the bore. On racing engines where they hone the cylinders with a torque plate, the pistons literally will not fit in the bores on an unstressed block. Try removing the spark plug and see if the engine turns over. Also, did you remove the piston? If you put the piston on backwards the ring end gaps will snag on the ports.
  4. BigBlue

    BigBlue Active Member

    Did you use a head gasket ? My guess is the piston is hitting the head. It's also a possibility the stud holes were drilled and tapped too deep at the factory. They may have Loctited the studs to the proper height and when you tightened the studs, they may have went too deep. Anything and everything is possible with these engines.

    You used 120 in/lbs and not 120 ft/lbs - correct? There is a BIG difference. I am not trying to be condescending, but I don't know your skills as a mechanic and some have done this in the past. I've made my share of mistakes in Life!!!

    Try removing the spark plug and see if it will turn over.

    You should be able to use some Channel Locks on the engine studs. I've removed studs this way with red Loctite. Grip in the center of the studs and turn counter clock-wise. Get a good grip on the studs. Once you get them out, buy some replacements. Grade 8 or higher. Also replace those nuts with grade 8 or higher.

    Good Luck,

    AKA: BigBlue
  5. Bzura

    Bzura Member

    I am confused. Are you saying your engine won't crank over with the cylinder removed like in your picture?
  6. Fabian

    Fabian Well-Known Member

    You do not need to apply any real torque to the head bolts when installing them in the engine case.
    In my experience with these engines, i have only hand tightened the head bolts with a dab of Loctite 243 applied to the head bolt threads.

    Removing head bolts was done using the double nut method.

    In over 30,000 miles of riding, i have never broken a head stud, and that's with all of my engines being supplied with 6mm studs, instead of the 8mm head studs that American customers receive.