In preparation for removing the engine from the frame, I remove the top end (valve covers, heads, cylinders, wrist pin, cylinders) to reduce the weight. Although not part of the engine top end, I also removed and inspected the cam followers as it is convenient to do that now.
This is not the first time I’ve done this. The 1983 R100RS motor is built the same as the 1983 R80ST motor, so the procedure I documented for the 1983 R100RS applies here as well. Rather than duplicate that procedure, here is the link to the documentation on the 1983 R100RS which contains all the details you need to complete this work.
This current document will provide a brief summary of the procedure with pictures of what I found as I did this work on the R80ST engine.
I did shoot a short video of doing this work on the R80ST.
VIDEO: 1983 R80ST Remove Engine Top End and Cam Followers
And here is the longer video I made for the 1983 R100RS which contains additional information you may find helpful. However, I didn’t show removing the cam followers in this one.
VIDEO: 1983 R100RS Remove Engine Top End
Remove Valve Cover, Valve Train And Cylinder Head
The left valve cover was held on with a single 6 mm nut. The other nut and the center nut are missing so it was easy to remove the valve cover.
Before I remove the intake and exhaust rockers and put them in labeled bags along with the retaining nuts, I test the cylinder studs to see if the threads in the aluminum engine block are stripped. I use my torque wrench set to 25 Ft-Lbs on each of the four cylinder stud nuts that secure the rocker arms. All held at 25 Ft-Lbs so the left side cylinder stud threads are sound. And, the right side cylinder studs are also sound.
I loosen the four cylinder stud nuts and the two head nuts at 12:00 and 6:00 in increments so the heads are not unduly stressed. I remove the rocker arms and put them in labeled bags so I can return them to their original location. I remove the push rods and label them so they go back on the same cam follower and in the same orientation so the balls on the end mate with the same cam follower and rocker arm tappet.
I carefully hit the head with my plastic mallet to loosen it from the head gasket and then pull the head off the cylinder studs. The piston crown has the typical build up of carbon on it.
Remove Cylinder And Piston
I use the plastic mallet and carefully hit the cylinder around the perimeter to loosen it from the sealant. I slowly pull it off the cylinder studs until the connecting rod is exposed. There is an O-ring on each of the top cylinder studs, but not on the bottom ones. The threaded holes for the top studs allow oil to enter the hole in the cylinder and head to lubricate the valve gear in the head and the O-rings seal that oil passage. There is also a large O-ring on the base of the cylinder which replaces the base gasket for sealing the bottom of the cylinder.
I put safety wire around the top two cylinder studs and under the connecting rod so when I pull the cylinder all the way off the connecting rod it won’t drop and nick the engine case. If the engine case gets nicked it will leak oil and a small nick in the connecting rod weakens it.
Then I slide the cylinder off the cylinder studs exposing the piston. As insurance, I stuff a shop towel under the connecting rod to protect the engine case. I remove the head gasket from the top of the cylinder
I use snap ring pliers to remove one of the snap rings that secure the wrist pin. I push the pin out with my finger and remove the piston and rings. Then I reposition the safety wire so it goes through the little end of the connecting rod and stuff another shop towel around the top of the connecting rod.
These are the markings on the cylinders. The S-like trademark symbol to the left of the numbers on the top of the cylinder (0982/4 1275) indicate these were supplied to BMW by Kolben Schmidt. The same cylinder is used on the left and right side of the engine.
Here is the engine block with the top end removed and the connecting rod protected with safety wire and rags stuffed around it.
Remove Cam Followers And Inspect For Damage
Although not part of the engine top end, I remove the cam followers and inspect them. I use a paper clip inserted into the oil hole in the center of the cam follower to remove it.
I don’t use a magnet as it will magnetize the follower and it will attract steel bits than can damage the face of the cam follower and cam lobe.
I make sure each cam follower goes back where it came from by putting them in the same bag as the rocker arm assembly they are associated with. I inspect each one for signs of damage. The face should be shinny like a mirror with no scratches, pits or rust. The slots in the sides of the cam follower should show no signs of cracking. The cup in the center of the cam follower with the hole in the middle for oil has a ridge and it should not be dented or deformed.
If you don’t position the push rod ball in the center of the cup when assembling the valve train, it can end up on the ridge of the cup. When you torque the head bolts the ball will damage the ridge around the cup.
Here’s what the bike looks like with the top end removed. I’m ready to start removing the engine from the frame.