Here are a few pictures of my 1963 R69S BMW. When I purchased it the engine hadn't been run since 1974. The first thing I did was drain the fluids as a matter of course. Finding bearing cage in the transmission fluid stopped me in my tracks from firing it up. What good is getting it running if you can't ride it? It would be 8 or so years before I'd get back to working on it.
So to do a proper job of it I stripped the engine down first to clean the slingers and give a good overall inspection.
I few interesting things came from the engine strip. Being an early 69S many of the engine components were stamped or etched with numbers and such. The crankshaft was etched in several places and the flywheel was stamped 'R69'
The previous owner had told me that it would need to have the heads re-done as it had a Triumph valve installed at one point. No need to play games, the heads were sent off to Randy Long in Pa for a complete overhaul. The pistons though are a an interesting thing, the tops and bottom of the skirts were knurled. having done a quite a few pre-70's boxer engines in the past fifteen years, this came as a new surprise to me! not having a good set on hand they went back in as its easy enough to swap in a new set in the future.
Reassembly was per usual, uneventful. One note to those that are doing their own boxer engine; get the steel crankshaft timing gear good and hot! Get it really hot so you need to use thick gloves to install it. I decent paint stripping gun can get it to that heat. In any case, when its good and hot it drops right on with a click. This also applies to all BMW boxer engines.
The rest of the drive train was gone through; new seals for the final drive so as to use GL-4 gear lube. early seals were only design for 40 SAE engine oil, and with age they really aren't up to the task anymore. In this case, the seals were leaking and had ruined the brake shoes. Lucky me was able to find a NOS set on the shelf at Duncan's shop [Duncan's Beemers; Maynard, Mass. 1-978-897-2697] Rebuilding the transmission was basic as usual; replace all the bearings and seals giving special attention to the adjustment of the shifting forks and shimming.