Monday 30 December 2013

Stripped threads

Well the crankcase is back on, the pistons on with new circlips and a couple of new washers on 2 of the cylinder bolts (2.31 euros a piece for a couple of steel washers!). The heads back on and torquing up the bolts and one of the last bolts strips the thread out of the barrel - shit... of with the head and then decision time. Do I remove the cylinder to drill out the hole and rethread? In the end laziness got the better of me and I drilled, threaded and screwed in the thread insert and broke off the fitting tab and then spent some minutes ensuring no swarf had gone anywhere near the engine internals.

The head went back on and then I managed to strip the other thread on cylinder 4... I don't know if it's the temperature, the age of the aluminium or just the non-stop dismantling that these engines were probably never designed to endure.

Anyway I did the second one in situ too and it went OK. And to cut a long story short the same thing happened on the front head, so I preempted and installed thread inserts in both holes on cylinder 2. I will refit tomorrow and try and fit the front head again to see if I can torque it up correctly. I decided to do both as I had to remove the cylinder as the exhaust valve cannot be removed with the cylinder in place!

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