3.30. Top End Teardown

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Top End Teardown


By Clayton Lubbers, edits by Ken Hansen


This is assuming you have the engine out of the frame and sitting on a stand or spot ready to work. Be sure you have an organized way to remove your parts; I use a Styrofoam egg carton and place my nuts/bolts in it starting at one end working towards the other. You can use the “cover” side for large parts.


Tools: Sockets/wrenches: 10mm, 12mm, 17mm.




1. Remove the spark plugs


2. Remove the tappet cover nuts and covers.


3. Remove the cam covers.


4. If you have a 1979 or earlier points ignition or have converted to Boyer-Bransen ignition, you must also remove the advance weights and points plates.


5. Remove the advance/ points rod from the camshaft


6. Remove the top end oil feed (the pipe on the front side of the engine) using a 17mm wrench. Be careful- the top bolts have copper washers between the bolt and the tube and the tube and the engine head.


7. Loosen and remove the eight 17mm head nuts. Also loosen and remove the four 12 mm head bolts.


8. Remove the rocker box (the top of the head). It may need a little “persuasion” to come off, but it only uses gasket sealer to stay on. Do not pry on the fins! Pry gently near the base of the tappet- cover studs, and it should come loose. Another method is to rotate the engine using the nut on the charging rotor. The pressure from the camshaft moving the rockers also should lift the rocker box.


9. Loosen the cam chain adjuster all the way and remove it.


10. You should be able to now lift the camshaft up a bit and slide off the two pairs of camshaft bearings.


11. Lift the cam chain off the camshaft. Using some finesse and wiggling, you should be able to begin sliding out the camshaft. BEFORE REMOVING IT COMPLETELY attach a wire to the cam chain to keep it from being lost on the nether-regions of the engine. This will aid in reassembly.


12. Remove the 12mm bolts near the spark plugs.


13. Remove the 10mm bolt at the rear of the engine above the cam chain adjuster.


14. Remove the two 10 mm bolts that hold the cam chain guide.


15. Gently remove the head. You should be able to pry it loose from the cylinders by prying near the rear of the head/cylinders. Again, do not pry on the fins! By rotating the engine you can now move the pistons up and down- be careful of the cam chain movement/binding.


16. Gently lift up on the cylinders. You should be able to slide them up off the pistons. BE CAREFUL not to let the pistons fall down roughly on the engine. This could damage the pistons.

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