BMW R850 Maintenance Manual page 39

After the first valve is adjusted, the second valve will then be adjusted while the first is
stabilized. To check if a valve is properly adjusted, attempt to insert the next thicker size
of feeler gauge -- it should be too big to fit. The valve clearance may change as you
tighten the lock nut. Experiment with tightening technique to maintain clearance as you
tighten, and recheck the clearances after all four valves on one side have been adjusted.
The two exhaust valves are located nearest to the exhaust pipe. Adjust exhaust = .012
in (.30 mm). Adjust intake = .006 in (.15mm). Rotate engine 360 degrees, center OT in
timing hole, and adjust the valves on the other side.
ROCKER ARM SIDEPLAY ADJUSTMENT
Mick McKinnon points out that there is one additional gap to check while the valve
covers are off. The rocker arms, which are the vertical metal pieces that contain the
valve adjustment nuts, will move up or down when pushed by hand. Measure the two
gaps where the rocker arms contact the horizontal piece at the bottom. This horizontal
piece has several names, including lower rocker arm bearing carrier (LRABC) and
rocker arm end plate. This lower rocker arm bearing carrier (LRABC) is held in place by
three T45 torx screws in a triangle pattern (on its side) and one large head bolt. The
gaps should be between .05mm and .30mm. The smaller the gap the quieter the
engine. The procedure is to loosen the 3 Torx screws and, after marking the lower head
bolt, loosen it also. Snug them back up just enough to hold an adjustment and then tap
the LRABC until you have about .05mm end play (gap). Check the gap after tightening
because it may tighten up slightly as you torque the screws and bolts back to spec.
Retorque the T45 torx screws to 15 ft.lb. Retorque the head bolt to 17 ft.lbs. and then
turn the bolt an additional 180-degrees (torque it and then move the wrench through
another half circle).
Clean valve covers and reinstall; the gasket surface MUST be free of all oil film or they
won't seal. Be certain the center donut gasket is in place on the valve cover !!! Reinstall
sparkplug, plug wire and valve cover strip; alternator cover - reinstall top right Allen bolt
first; timing hole plug - be careful when reinstalling this plug that you do not push it all
the way through, into the hole. Editors Note: One trick is to stab the rubber plug in the
middle with a sharp awl to hold it in place while you carefully push the edges in with a
long screwdriver.
Copyright© 1997, Stephen Karlan(Dali Meeow) <dali@netrox.net>, Miami, Florida
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