Just wanted to offer a word of caution to those of you out there dealing with engine knocks. In my case I acquired a 2002 750, with under 4700 miles, that had a " rapping" sound that seemed to be coming from the upper portion of the front cylinder. I got a lot of advice about acct's. valves, etc. and did a lot of checking to try and determine the cause. After finally deciding to remove the engine, I removed the front cyl. head and cyl. exposing the front piston and found that it had obviously spun the connecting rod bearing. Just wanted to let you know because the longer an engine runs like this, the more the damage will be.