I was plagued by vibrations a few weeks ago with 2 bgf motors in a70's-80'scruiser. A third bgf went into a Panama Jack and it's livable (photos forthcoming). So, I was on the verge of sending the crank away to be balanced. After studying the formulas on line and visiting a friend with an automotive machine shop, I concluded that I could do the job myself. I really didn't want to split the crank so I used the same formula but utilized the conrod as part of the bobweight. Now the motor revs high and vibrate's little at max rpms. Very rideable. I had to take off considerable weight at the rod pin. Also I didn't have to use the head or muffler brace. I want to thank all who responded to my first thread with some great suggestions.