been working on my new '74 CB 550. It had only run for a few minutes, but it RAN.
I had just installed the valve covers (using rubber bands, thanks to these forums) and adjusted the tappetts. I wanted to test the compression. Looked good in #1, but couldn't get a reading in #2. Something was blocking the end of the compression tester from sealing with the spark plug hole. I looked in with a flashlight, saw something, tried to grab it, and then it disappeared... into the pit.
Then the engine wouldn't turn over. Got near to TDC for cylinders #2 and #3, stopped dead. Tried rotating backwards... same thing. The dreaded bolt in the cylinder!
I really did not want to pull the head. But as a doctor, I have a flexable fiberoptic scope, for looking in ears. About $40 on Ebay, the only way I had been able to look into my own ears. So I fired it up on a laptop, looked down the sparkplug holes.
I had been installing stainless steel hex drive screws on the valve cover, and I was dreading that I would find one down the hole, since they are non-magnetic. But I found instead an Allen drive bit, which I must have lost when removing the old screws. One trip to WalMart, $4 for a magnetic pick up probe, and out it came on my second try. Wow, I am so relieved. Engine turns over again, and has compression!
Of course I really could have found it without the scope to see it, but it was so satisfactory to see what I was after.