BMW R850 Maintenance Manual page 36

MAJOR SERVICE:
For a Major Service, perform all of the service items called for in a minor service, and in
addition perform the following:
Change the Transmission Oil: With the bike fully warmed up, drain the transmission
oil and refill the transmission. The fill plug is readily identifiable on the right side of the
transmission. The drain plug is not in the bottom of the transmission, where it would
dump oil onto the catalytic converter and exhaust system. It is located beneath the fill
plug on the right side of the transmission, recessed into the "tunnel" cast into the lower
right side of the transmission case. BMW specifies 80, 90, or 80w90 wt gear oil.
Consult your manual for the temperature ranges. Fill the transmission to the bottom of
the fill hole threads. This is a specified quantity of 800cc. Use new sealing washers on
the drain and fill plugs.
Change the Final Drive Oil: With the bike fully warmed up, drain the final drive oil and
refill the final drive. Use the same gear oil as for the transmission. Fill the final drive to
the bottom of the fill hole threads. This is a specified quantity of 230cc. Use new
sealing washers on the drain and fill plugs.
Renew the Air Filter.
Renew the Fuel Filter: The fuel filter is located inside the fuel tank. As an aside - when
I first serviced my K bike, I concluded that the fuel filter was installed in the most
obnoxious manner possible. I had to remove the entire gas tank filler cap and remove
and replace the filter located in the bottom of the tank. When I first serviced an R1100, I
discovered that BMW had devised an even more obnoxious location for the fuel filter.
Locate and identify the two fuel hoses and two vent hoses beneath the right side of the
fuel tank. Pull the two vent hoses loose at the inline connector. Clamp-off (I use small
vice grips) both rubber fuel lines forward of where they attach to the hard black lines to
which they connect. Remove the fuel lines where they connect and remove the tank.
Drain the tank. Locate the metal plate affixed to the side of the tank in the tunnel where
the tank straddles the engine. Remove the capscrews which attach the plate and fuel
pump assembly to the tank. Retract the plate about one inch from the tank and loosen
the two vent hoses connected to the inside of the plate, inside the tank. Carefully
withdraw the fuel pump assembly - with the filter, fuel pump, and fuel level float arm -
from the tank. It will seem like you are trying to extract about 7 inches of parts through a
5 inch hole - but by carefully positioning the float arm it will all come out without bending
or breaking anything, and without force.
Remove the old fuel filter and install the new filter. To reinstall the plate you will need to
use a new (large) sealing "O" ring for the plate. You will want to replace the crimp-on
clamps on the two vent hoses with two very small screw-type or spring-type hose
clamps. WARNING: These two vent hoses are submerged in gasoline inside the fuel
tank. If the hose connections inside the tank leak, then fuel will leak out through the vent
hoses. If this happens, you will be privileged to again remove the fuel tank and the fuel
pump assembly to renew the clamps and stop the leak.
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