Originally Posted by bmwrench
marksb'ville's memory is right, and mine was wrong. One summer in the late '70s, it seemed like all I did was rebuild unit 650/750 motors-or more accurately, replace crank bearings. Not only did we leave the gearbox internals in place, we also lefft the cam gears on.
If it hasn't been mentioned already, pull and clean the sludge trap. and repalce the rod bolts.
Wherever you are Dad, thank you.
...and be careful the rod bolts you get aren't Chinese rubbish. +1 on the sludge trap... this one was 50% blocked, but only had 100,000 miles on it, yes, that's right. My buddie and I rebuilt it last in 1980, he rode it cross country 3 times and everywhere else. Top end was wheezing, so we pulled it back down, sludge trap was the whole reason we opened the bottom.