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Cota 348 Mr Opening The Engine

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i am trying to open the engine. removed head of cylindre but i cannot with the cylindre itself from the engine. There are 4 holes and i can see nuts inside close to the large screws where the head assemblies.


any advice?




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From the late John Haberdosch:


Procedure for removal:


Remove Cylinder Head:

  1. It will typically take a 17mm socket to remove the 10mm nuts.
  2. Insert 7mm Allen wrench into hole and engage sleeve nut. 
  3. Turn counterclockwise and unscrew from stud.
  4. Remove with pencil magnet.
  5. Tap cylinder with rubber or dead blow hammer to loosen connection.  Strike against the edge of the fins, not on top or bottom of them.  You can also strike beneath the intake manifold and exhaust port.  Do not use a hard hammer.
  6. Slide cylinder up part way.
  7. Press rags or paper kitchen towels in crankcase beneath piston.
  8. Remove cylinder.


This all seems very simple.  About 1 out of every 2 engines has a severely stuck sleeve nut.  You can soak the nut with liquid wrench or any number of penetrating oils and let it stand for a day or more.  I haven’t the patience.  Even after a week of using penetrant it only works about 1/10th of the time.  What to do, what to do?  Heat?  Doesn’t work.  Maybe the stud will pull before the Allen wrench rounds off the inside of the nut.  Been there, done that.  The sleeve nut will round out.  Once you rounded out the nut it’s time to drill.



  1. Get some cutting oil and an electric drill.
  2. Select a suitable sharp drill bit.  Make the selection of a size that will only drill the stud out.  Remove all of the sleeve nuts that can be removed.
  3. You don’t want to drill into the cylinder casting.
  4. Start drilling.  This will take some time but at least you will feel like you are doing something.
  5. Remove chips occasionally with the pencil magnet.
  6. Measure your progress in some fashion.
  7. Resume drilling.  Eventually you will destroy enough of the stud to remove the cylinder.
  8. Use locking pliers and remove the remains of the stud.
  9. Order another stud and nut.


There are special steel washers at the bottom of those holes for the sleeve nut to press against.  If they fall out; save them.  If they stayed in the hole, leave them there.  Just remember to return the washers to the correct holes on reassembly.  Clean all nuts and loose washers.  Use a 7mm x 1.00 tap and die to clean the threads.


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You need a T handle hex wrench that is larger than the socket in the sleeve nut. Carefully grind it to reduce the across flats dimension so it will not quite fit into the sleeve nut, a slight taper on the last 2 mm of the flats gives an indication of nut size. When it is ground to slightly oversize hammer it into the sleeve nut. Then get someone to apply quite a bit of torque on the T wrench with both hands whilst you strike the end with a copper hammer.

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