So I thought I'd set the valve clearances on the Rockster this afternoon. Should be a 45 minute job methinks. First thing I noticed is a fair bit of end play on one of the rocker shafts. So I backed off the head nut and 3 bolts so I could adjust it. Went to do the Torx bolts back up to specified torque and one of them shears off leaving about an inch of thread inside the rocker carrier casting. So the 45 minute job became a 3 hour job as I had to remove the cam chain sprocket so I could get the rocker carrier off. I then had to drill apilot hole in the remaining bit of bolt and use a screw extractor to remove it.
Well done BMW. The bolts you fit can't even be retorqued without shearing. And they're only 40Nm items that play no role in holding down the head so designed in stretch etc doesn't seem to be required.
Fortunately I had a good stock of M8 socket cap screws so was able to rebuild with new bolts. The only good thing is that the bike is a lot quieter now. Just a shame it had to be such a bitch of a job.
More fasteners made of exotic cheese
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