BMW AG Motorcycle (R 850 C, R 1200 C). Manual - part 5

11.5

11

Technical data

R 850 C

R 1200 C

Engine, general

Engine design

Four-stroke flat twin, air-cooled with oil-
cooled exhaust ports, installed longitudinal-
ly, 4 valves per cylinder, two high-mounted 
camshafts, electronic fuel injection.

Location of engine number

Crankcase

Cylinder bore

mm (in) 87.5 (3.44)

101 (3.97)

Stroke

mm (in) 70.5 (2.77)

73 (2.87)

Effective displacement

cc 848

1170

Compression ratio

10.3 : 1

10.0 : 1

Power output

kW (bhp)/min

-1

37 (50)/5250

45 (61)/5000

Max. torque

Nm/min

-1

71/4750

98/3000

Permissible maximum engine speed

min

-1

7000

Idle speed

min

-1

 750

+150

Direction of rotation

Clockwise, looking at ignition system

Compression test pressure

good
normal
poor

bar (psi)
bar (psi)
bar (psi)
bar (psi)

above

10 (142)
8.5...10 (121...142)

below 8.5 

(121)

Intake port dia./cylinder head

mm (in) 45 (1.77)

Lubrication system

Theoretical volume in circulation at 6000 min

-1

Lubricating oil

Cooling oil

l (Imp. gal/

US gal)

l (Imp. gal/

US gal)

36 (7.92/9.51)

30 (6.60/7.93)

Oil filter

Full-flow type

Pressure differential needed to open bypass valve

bar (psi) 1.5 (21.3)

Oil pressure warning light comes on below

bar (psi) 0.2...0.5 (2.8...7.1)

Pressure relief valve opens at

bar (psi) 5.5 (78.3)

Operating pressure

bar (psi) 3.5...6.0 (49.8...85.4)

Oil content

Without filter change

With filter change

min/max

l (Imp. pint/

US quart)

l (Imp. pint/

US quart)

l (Imp. pint/

US quart)

3.50 (6.2/3.69)

3.75 (6.6/3.96)

0.5 (0.88/0.53)

Permissible oil consumption

l/1000 km (miles per Imp. pint/miles per US quart) 1.0 (350/590)

Oil pump

Oil pump

2 Duocentric pumps

Housing depth

mm (in)
mm (in)

12.02...12.05 (0.473...0.474)
10.02...10.05 (0.394...0.396)

Height of rotor

mm (in)
mm (in)

11.95...11.98 (0.470...0.472)

9.95...9.98 (0.392...0.393)

Axial play

mm (in) 0.04...0.1 (0.002...0.004)

Wear limit

mm (in) 0.25 (0.010)

11.6

Technical data

R 850 C

R 1200 C

Valves

Included angle between valves

° 41

Valve clearances with engine cold 
(max. 35 °C/95 °F)

0.15 (0.006)
0.30 (0.012)

Inlet valve

mm (in)

Exhaust valve

mm (in)

Valve timing

At zero valve clearance and 3 mm (0.12 in) 
valve lift

Inlet opens

17° after TDC

Inlet closes

15° after BDC

Exhaust opens

15° before BDC

Exhaust closes

17° before TDC

Tolerance ± 3°

Valve head dia.

Inlet

mm (in) 32 (1.26)

34 (1.34)

Exhaust

mm (in) 27 (1.06)

29 (1.14)

Stem dia.

Inlet

mm (in) 4.966...4.980 (0.1955...0.1960)

Wear limit

mm (in) 4.946 (0.1947)

Exhaust

mm (in) 4.956...4.970 (0.1951...0.1956)

Wear limit

mm (in) 4.936 (0.1943)

Valve head edge thickness

Inlet

mm (in) 1.00 

±0.2 

(0.04 

±0.008

)

Wear limit

mm (in) 0.5 (0.02)

Exhaust

mm (in) 1.00 

±0.2 

(0.04 

±0.008

)

Wear limit

mm (in) 0.5 (0.02)

Max. runout of valve head at valve seat

Inlet, exhaust

mm (in) 0.035 (0.0014)

Valve seat ring

Valve seat angle

Inlet

45°

Exhaust

45°

Valve seat width

Inlet

mm (in) 1.1 

± 0.15 

(0.043 

±0.006

)

Wear limit

mm (in) 2.5 (0.10)

Exhaust

mm (in) 1.4 

± 0.15 

(0.055 

±0.006

)

Wear limit

mm (in) 3.0 (0.12)

Valve seat extl. dia. (dimension for machining seat)

Inlet

mm (in) 31.4 

±0.1 

(1.24 

±0.004

) 33.4 

±0.1 

(1.32 

±0.004

)

Exhaust

mm (in) 26.4 

±0.1 

(1.04 

±0.004

) 28.4 

±0.1 

(1.12 

±0.004

)

Seat ring dia. (oversize +0.2 mm/+0.008 in)

Inlet

mm (in) 34.634...34.650 

(1.3635...1.3642)

36.617...36.633 
(1.4416...1.4422)

Exhaust

mm (in) 30.134...30.150 

(1.1864...1.1870)

32.134...32.150 
(1.2651...1.2658)

Seat dia. in cyl. head (oversize +0.2 mm/+0.008 in)

Inlet

mm (in) 34.500...34.525 

(1.3583...1.3592)

36.500...36.525 
(1.4370...1.4380)

Exhaust

mm (in) 30.000...30.025 

(1.1811...1.1821)

32.000...32.025 
(1.2599...1.2608)

11.7

Technical data

R 850 C

R 1200 C

Valve guide

Valve guide

Extl. dia.

mm (in) 12.533...12.544 (0.4934...0.4939)

Bore in cylinder head

mm (in) 12.500...12.518 (0.4921...0.4928)

Overlap

mm (in) 0.015...0.044 (0.0006...0.0017)

Repair stages

Replacement valve guide Extl. dia.

mm (in) 12.550...12.561 (0.4941...0.4945)

Oversize valve guide

Extl. dia.

mm (in) 12.733...12.744 (0.5013...0.5017)

Valve guide

Intl. dia.

mm (in) 5.0...5.012 (0.1969...0.1973)

Radial clearance

Inlet

mm (in) 0.020...0.046 (0.0008...0.0018)

Wear limit

mm (in) 0.15 (0.006)

Exhaust

mm (in) 0.030...0.056 (0.0012...0.0022)

Wear limit

mm (in) 0.17 (0.007)

Valve spring

Spring length, off-load

mm (in) 41.1 (1.62)

Wear limit

mm (in) 39.0 (1.54)

Rocker

Bore dia.

mm (in) 16.016...16.027 (0.6306...0.6310)

Rocker shaft dia.

mm (in) 15.973...15.984 (0.6289...0.6293)

Radial clearance

mm (in) 0.032...0.054 (0.0016...0.0021)

Wear limit

mm (in) 0.1 (0.004)

Axial play

min.

mm (in) 0.05 (0.002)

max.

mm (in) 0.40 (0.016)

Camshaft

Opening angle, inlet/exhaust cams

256°/256°

Cam spread, inlet/exhaust

106°/109°

Marking

Marking in 
position 2

Inlet valve lift

mm (in) 8.23 (valve clearance = 0)

Exhaust valve lift

mm (in) 8.23 (valve clearance = 0)

Camshaft bearing bore dia.

mm (in) 21.02...21.04 (0.8276...0.8284)

Camshaft dia.

mm (in) 20.97...21.00 (0.826...0.827)

Radial clearance

mm (in) 0.02...0.07 (0.0008...0.0028)

Wear limit

mm (in) 0.15 (0.006)

Width of guide bearing

mm (in) 15.92...15.95 (0.6268...0.6280)

Width of camshaft bearing

mm (in) 16.0...16.05 (0.630...0.632)

Axial play

mm (in) 0.08...0.13 (0.0031...0.0051)

Wear limit

mm (in) 0.25 (0.010)

11.8

Technical data

R 850 C

R 1200 C

Bucket-type tappet

Extl. dia.

mm (in) 23.947...23.960 (0.9428...0.9433)

Bore dia. in cylinder head

mm (in) 24.000...24.021 (0.9449...0.9457)

Radial clearance

mm (in) 0.040...0.074 (0.0016...0.0029)

Wear limit

mm (in) 0.18 (0.007)

Auxiliary shaft

Bore dia. in crankcase

front/back

mm (in) 25.020...25.041 (0.9851...0.9859)

Auxiliary shaft dia.

front/back

mm (in) 24.959...24.980 (0.9827...0.9835)

Radial clearance

mm (in) 0.040...0.082 (0.0016...0.0032)

Wear limit

mm (in) 0.17 (0.007)

Crankshaft

Marking of main bearing and crankpin on 
front crank web

no paint mark

Grinding stage 0

paint mark

Grinding stage 1 (-0.25 mm/-0.010 in)

Grrinding stage 0
(grinding stage 1 = —0.25 mm/—0.010 in)

Guide bearing bore dia.

mm (in) 64.949...64.969 (2.5571...2.5579)

Guide bearing dia.

mm (in) Green: 59.964...60.003 (2.3609...2.3624)

Yellow: 59.974...60.013 (2.3612...2.3628)

Main bearing journal dia.

mm (in) Green: 59.939...59.948 (2.3598...2.3602)

Yellow: 59.949...59.958 (2.3602...2.3606)

Radial clearance

mm (in) 0.016...0.064 (0.0006...0.0025)

Wear limit

mm (in) 0.1 (0.004)

Main bearing bore dia.

mm (in) 60.000...60.019 (2.3622...2.3629)

Main bearing dia.

mm (in) Green: 54.998...55.039 (2.1653...2.1669)

Yellow: 55.008...55.049 (2.1657...2.1673)

Main bearing journal dia.

mm (in) Green: 54.971...54.980 (2.1643...2.1646)

Yellow: 54.981...54.990 (2.1646...2.1650)

Radial clearance

mm (in) 0.018...0.068 (0.0007...0.0028)

Wear limit

mm (in) 0.13 (0.0051)

Width of guide bearing

mm (in) 24.890...24.940 (0.9799...0.9819)

Bearing width of main bearing journal

mm (in) 25.020...25.053 (0.9851...0.9864)

Axial play

mm (in) 0.080...0.163 (0.0031...0.0064)

Wear limit

mm (in) 0.2 (0.008)

Grinding stage 0
(grinding stage 1 = –0.25 mm/—0.010 in)

Crankpin dia.

mm (in) 47.975...47.991 (1.8888...1.8894)

Bearing width of crankpin

mm (in) 22.065...22.195 (0.8687...0.8738)

11.9

Technical data

R 850 C

R 1200 C

Connecting rod

Bore dia. for big end bearing

mm (in) 51.000...51.013 (2.0079...2.0084)

Big end bearing dia.

mm (in) 48.016...48.050 (1.8904...1.8918)

Radial clearance

mm (in) 0.025...0.075 (0.0010...0.0030)

Wear limit

mm (in) 0.13 (0.0051)

Width of big end bearing eye

mm (in) 21.883...21.935 (0.8616...0.8636)

Conrod end float

mm (in) 0.130...0.312 (0.0051...0.0123)

Wear limit

mm (in) 0.5 (0.02)

Small end bearing bore dia.

mm (in) 22.015...22.025 (0.8667...0.8671)

Radial clearance

mm (in) 0.015...0.030 (0.0006...0.0012)

Wear limit

mm (in) 0.06 (0.002)

Distance between centers

mm (in) 125 (4.92)

Max. deviation from parallel of conrod bores 
at 150 mm (5.90 in) spacing

mm (in) 0.07 (0.003)

Cylinders

Bore

(20 mm/0.79 in from top edge)

A

mm (in) 87.492...87.500

(3.4446...3.4449)

100.992...101.000 
(3.9761...3.9764)

Wear limit

mm (in) 87.550 (3.4468)

101.050 (3.9784)

B

mm (in) 87.500...87.508

(3.4449...3.4452)

101.000...101.008 
(3.9764...3.9768)

Wear limit

mm (in) 87.558 (3.4471)

101.058 (3.9787)

Total wear clearance of piston and cylinder

mm (in) 0.12 (0.005)

Permitted out-of-roundness of cylinder bore

20 mm (0.79 in) from the top edge

mm (in) 0.03 (0.0012)

100 mm (3.94 in) from the top edge

mm (in) 0.04 (0.0016)

Pistons

Piston dia.

(Measuring plane A — see Checking pistons and 
cylinders

A

mm (in) 87.465...87.477

(3.4435...3.4440)

100.971...100.983 
(3.9753...3.9758)

Wear limit

mm (in) 87.390 (3.4405)

100.895 (3.9723)

B

mm (in) 87.477...87.485

(3.4440...3.4443)

100.983...100.995 
(3.9753...3.9763)

Wear limit

mm (in) 87.400 (3.4409)

100.905 (3.9727)

AB

mm (in) 87.473...87.481

(3.4438...3.4441)

100.979...100.987 
(3.9756...3.9759)

Wear limit

mm (in) 87.395 (3.4407)

100.900 (3.9725)

Installed clearance

mm (in) 0.011...0.035

(0.0004...0.0013)

0.005...0.029 
(0.0002...0.0011)

Total wear clearance of piston and cylinder

mm (in) 0.12 (0.005)

Piston pin bore dia.

mm (in) 22.005...22.011 (0.8664...0.8666)

Weight classes

+ and —

Weight difference in one class

grammes

 (oz) 10 (0.353) (complete with pins and rings)

Direction of installation

Arrow on piston crown pointing to exhaust side

Production locating point towards exhaust side 
(see Installing piston)

11.10

Technical data

R 850 C

R 1200 C

Piston rings

1st groove

Piston ring
asymmetrical, convex oval

Height

mm (in) 1.170...1.190 (0.0461...0.0469)

Wear limit

mm (in) 1.1 (0.043)

Gap clearance

mm (in) 0.1...0.3 (0.004...0.012)

Wear limit

mm (in) 0.8 (0.031)

Side clearance

mm (in) 0.030...0.070 (0.0012...0.0027)

Wear limit

mm (in) 0.15 (0.0006)

2nd groove Micro-taper compression ring

Height

mm (in) 1.170...1.190 (0.0461...0.0469)

Wear limit

mm (in) 1.1 (0.043)

Gap clearance

mm (in) 0.2...0.4 (0.008...0.016)

Wear limit

mm (in) 1.0 (0.040)

Side clearance

mm (in) 0.030...0.070 (0.0012...0.0027)

Wear limit

mm (in) 0.15 (0.0006)

3rd groove Equal-chamfer ring + tubular spring

Height

mm (in) 1.970...1.990 (0.0776...0.0783)

Wear limit

mm (in) 1.9 (0.075)

Gap clearance

mm (in) 0.30...0.55 (0.012...0.022)

Wear limit

mm (in) 1.20 (0.047)

Side clearance

mm (in) 0.020...0.060 (0.0008...0.0024)

Wear limit

mm (in) 0.15 (0.0006)

Installed direction of piston rings

“Top” marking uppermost

Piston pin

Piston pin dia.

mm (in) 21.995...22.000 (0.8660...0.8662)

Wear limit

mm (in) 21.960 (0.8646)

Bore dia. in piston

mm (in) 22.005...22.011 (0.8664...0.8666)

Radial clearance in piston

mm (in) 0.005...0.016 (0.0002...0.0006)

Wear limit

mm (in) 0.070 (0.0027)

11.11

Sectioned drawing of engine

11.12

Lubricating oil circuit