Service bulletins related to engine, transmission, driveshaft and final drive will be posted here. In general, I started with the earliest ones first, but you will find that the order isn’t exact. Long story.
Many of the older service bulletin titles will show “engine” first, and that is my shorthand method for the entire drivetrain.
Protection for the transmission coupling flanges June 1952
Transmission oil return improvements July 1952
Shorter cylinders R67/2 & R68 Nov. 1952
A clutch issue, all models, Clutch Center Plate Dec. 1952
R25, R25/2, final drive ring, engine, driveshaft ring Nov. 1952
The out of stock R24 cranks replaced by R25 cranks Jan 1954
R25, /2, /3 rubber U-joint, engine, driveshaft rubber July 1955
R50 & R69 driveshaft cover, engine, driveshaft Sept. 1955
R26 final drive oil seal, engine, final drive seal March 1956
Magnetic drain plug, engine, magnetic plug April 1952
R25/2 overheating , engine, overheat Sept. 1952
R67/2 pistons & rings, engine, piston June 1953
Polishing covers overheats the engine, engine, polishing May 1952
Motorcycle & Isetta light alloy rod, engine, rod Jan. 1957
R25/3 run in oil consumption, engine, run in time March 1954
Summer engine oil, engine, summer oil April 1956
R25/3, R51/3, R67/2 & R68 transmission leak, engine, transmission Oct. 1954
BMW, Isetta & Limousine valve guide, caps & locks Nov. 1959
Sidecar final drive ratio, engine, FD sidecar ratio Jan. 1963
R27 final drive ratio change, engine, R27 final drive ratio Feb. 1963
Increased R27 piston clearance, engine, R27 piston July 1963
Page 1, R27 oil pump, engine, R27 oil pump pg 1 Feb. 1964
Page 2 R27 oil pump, engine, R27 oil pump pg 2 Feb. 1964
R60-R69S clutch spring change, engine, clutch spring June 1964
Main bearing error, engine, main bearing error April 1964, related to the next bulletin below
Twin strange engine/transmission sounds, engine, twins, crank, transmission sounds Sept. 1964 To see the dial indicator recommended to dealers, here is the link. tool, Dial indicator , April 1964
Main bearing plate change, engine, main bearing plate Feb. 1965
U-joint on driveshaft failures, engine, U-joint Feb. 1965
Piston clearance chart, engine, piston clearance April 1965
Pushrod change, engine, push rod Oct. 1965
Speedo cable drive gear mod, engine, speedo drive gear Oct. 1965
Cylinder base gasket, engine, cylinder base gasket Nov 1965
Removing alloy exhaust nuts bulletin 78-4
Cylinder base gaskets bulletin 11-79-13NS
Engine oil cooler bulletin 4-79-4NS
Piston ring seating bulletin 2-78-5 N
Engine ID change, 1070 R, July 1979
Synthetic oil approved, 1079 R, no date
5-speed gearbox broken pawl spring 163 M, Jan 1975
/6 Flywheel bolt size increase 164 M, Jan 1975
Cylinder head and gasket change 1045R, June 1978
Piston wrist pin changes, 1047 R, June 1978
Gear shift mechanism improvement, 1049 R, June 1978
Cylinder base spacer, 1057 R, Sept. 1978
R100RS oil cooler installation, 1060 R, May 1979
Low oil pressure on all models, 1061 R, March 1978