BMW AG Motorcycle (R 850 C, R 1200 C). Manual - part 8

11.30

Removing cylinder barrel

•

Unscrew and remove guide rail bearing screw (1).

•

Unscrew and remove cylinder retaining screws, 
and remove cylinder.

e

 Caution:

When removing cylinder, ensure that the piston 
does not strike the engine block.

Removing/dismantling piston

•

Remove both retaining rings on piston pin.

•

Press out piston pin by hand.

•

Remove piston.

•

Carefully remove piston rings with piston ring 
pliers.

•

Remove carbonized oil from base of piston/clean 
the piston.

e

 Caution:

Do not accidentally confuse pistons, piston pins or 
piston rings.

RS110170

1

11.31

Checking pistons and cylinders

Reference 
temperature for measurements: ...... 20 °C (68 °F)

•

Measure cylinder bore with internal probe at 
20 mm (0.79 in) and 100 mm (3.94 in) from the 
top in direction of piston pin, and again at a right 
angle to the first measurement.

a

............................................See Technical data

Measuring plane A:......................... 6 mm (0.24 in)

a

............................................See Technical data

•

Install piston rings in cylinder.

•

Determine piston ring clearance using feeler 
gauge.

a

............................................See Technical data

Assembling pistons

•

Carefully fit piston rings to piston in the following 
sequence, using piston ring pliers: 
3rd groove - equal chamfer ring 
2nd groove - micro-chamfer ring 
1st groove - asymmetric, convex oval-section

a

............................................ See Technical data

e

 Caution:

The tubular-spring ring gap must be at 180° to the 
equal-chamfer ring gap. 
Install with “Top” uppermost.

RS110180

100

20

RS110970

A

RS110200

RS110190

1.

R 850

1.

2.

3.

11.32

Removing/installing conrod

•

Turn crankshaft to TDC position.

•

Lock the clutch housing with special tool 
BMW No. 11 5 640.

•

Remove conrod.

L

 Note:

Conrods can also be removed/installed with the 
crankshaft removed.

e

 Caution:

Do not accidentally interchange conrods or bearing 
shells.

•

Install conrods.

Installed direction of conrods: ..lettering facing up

e

 Caution:

Oil the bearings.

•

Screw the big end bolts in by hand, then tighten 
them with a tightening angle indicator, 
BMW No. 11 2 500.

e

 Caution:

Use big end bolts once only.

X 

Tightening torque:

Big end bolts oiled
Joint torque.................................................. 20 Nm
Wrench angle ................................................... 80 °

11 5 640

RS110210

TDC

11 2 500

11.33

Removing and installing alternator cover 
with engine installed

e

 Caution:

Disconnect earth (ground) lead from battery. 
Insulate earth (ground) lead.

•

Detach the horn.

•

Remove the oil cooler line.

•

Separate the Hall-effect signal transmitter plug.

•

Remove the starter motor.

•

Remove rear leading link mount.

Removing alternator mount cover

•

Detach the alternator.

•

Remove rotary breather line (1).

•

Lock the clutch housing with special tool 
BMW No. 11 5 640.

•

Remove pulley (2).

•

Remove magnetic gate (3).

L

 Note:

If complete alternator mount cover is removed, 
leave magnetic gate (3) installed.

•

Remove alternator mount cover (4).

11 5 640

RS110230

4

3

1

2

11.34

Renewing radial shaft seal in alternator 
mount cover

•

Carefully lever radial shaft seal out, using a 
screwdriver.

•

Drive in the new radial shaft seal with drift and 
sliding sleeve, BMW No. 11 5 680.

L

 Note:

Slide new radial shaft seal over taper on sliding 
sleeve, pre-shape and pull off.

Renewing radial shaft seal for rotary 
breather

•

Carefully lever radial shaft seal out, using a 
screwdriver.

•

Carefully pre-form the lip of the radial shaft seal 
by hand.

•

Oil the new radial shaft seal lightly and drive it in 
with handle, BMW No. 00 5 550, and drift, 
BMW No. 11 5 650.

11 5 680

RS110240

00 5 550

RS110241

11 5 650

11.35

Removing auxiliary shaft drive

•

Align markings (arrows) on timing pinion and 
chain sprocket.

•

Unscrew and remove cooling oil pipe (1)/swing 
the pipe forwards.

•

Remove chain tensioner (2).

•

Remove chain tensioning rail (3).

•

Remove chain guide rail (4).

•

Lock clutch housing with special tool 
BMW No. 11 5 640.

•

Unscrew and remove chain sprocket retaining 
bolt (5).

•

Remove rotor (6) with chain sprocket (7) and tim-
ing chain (8).

•

If necessary, remove chain sprocket (9).

11 5 640

RS110251

1

8

2

4

9

6

7

5

3

RS110961

11.36

Removing oil pump

•

Remove oil pump cover (1).

•

Remove complete oil pump (2) together with 
cooling oil pipe (3), and dismantle.

e

 Caution:

Check installed positions of parts which have al-
ready been run together.

RS110410

M6 x 45

M6 x 50

M6 x 45

M6 x 45

M6 x 50

3

1

2

11.37

Removing radial shaft seal on 
crankshaft with engine installed

•

Lock clutch housing with special tool 
BMW No. 11 5 640.

•

Remove the clutch. 

•

Carefully lever radial shaft seal out, using a 
screwdriver.

e

 Caution:

Avoid damaging the sealing faces on the housing 
and the crankshaft.

L

 Note:

When the crankcase is dismantled, the radial shaft 
seal can be taken out.

C210010

11 5 640

RS110270