Motorcycle BMW R1150RT. Manual - part 23

11.27

11 12 090 

Removing cylinder head

RS110110

M6 x 30

M6 x 30

M6 x 30

M10 x 70

11.28

11 12 232 

Disassembling, checking, 

repairing and reassembling cylinder 
head

11 34 Removing and installing valves

e

 Attention:

Do not scratch sealing face on cylinder head. Place 
the head on a clean, non-scratching surface.

•

Mount valve spring compressor, 
BMW No. 11 5 690, onto cylinder head.

•

Compress the valve springs.

•

Gently tap valve head to release collets from 
spring retainer.

•

Remove valve collets.

•

Relieve tension on valve springs.

•

Remove top and bottom spring retainers, valve 
springs and valves.

11 34  Removing valve stem seals

L

 Note:

The valve stem seal must always be replaced when-
ever a valve is removed.

•

Pull off valve stem seal with pliers, 
BMW No. 11 1 250.

RS110130

11 5 690

11 1 250

11.29

Checking valves for wear

•

Clean combustion residue from valves.

•

Check valve dimensions (

a

11.6).

Remachining valve seat

e

 Attention:

Width (B) and diameter (D) must always be main-
tained if valve seat is machined (

a

11.7).

Checking and repairing cylinder head

•

Remove combustion residue from combustion 
chamber.

•

Check sealing face for damage/distortion, and 
machine if necessary.

Milling head mating surface: 

.................... max. 0.2 mm (0.008 in) metal removal

Checking valve guide for wear

•

Check valve guide bore (

a

11.7).

RS110890

B

D

11.30

Replacing valve guides

e

 Attention:

Wear protective gloves when handling heated parts.

•

Heat cylinder head slowly and uniformly to 
200 °C (392 °F) in a suitable oven.

•

Drive out valve guides with 5 mm (0.1969 in) dia. 
drift, BMW No. 11 5 674, from the combustion 
chamber side.

•

Allow cylinder head to cool down to room tem-
perature (approx. 20 °C/68 °F).

•

Examine valve guide bore for:

–

wear,

–

widening taper and

–

correct dimensions in H7 tolerance range 
(12.500...12.518 mm/0.4921...0.4928 in).

L

 Note:

Valve guides are press-fitted in the cylinder head 
with an interference fit of 
0.015...0.044 mm (0.0006...0.0017 in).

If valve guide bore is undamaged but slightly lar-
ger than the 12.5 H7 tolerance range:

•

Use replacement valve guide 
12.550...12.561 mm (0.4941...0.4945 in).

If valve guide bore is damaged or not to correct 
dimensions in 12.5 H7 tolerance range:

•

Use an oversize 12.7 u6
(12.733...12.744 mm/0.5013...0.5017 in) valve 
guide.

Repair method 1 – ream out the bore
(if bore is damaged or not to correct dimensions) 

•

Determine actual diameter of valve guide using 
micrometer.

•

Ream bore with Ø12.7 mm (0.5000 in) H7 
(12.700...12.718 mm/0.5000...0.5007 in) reamer.

Repair method 2 – turn the valve guide on a lathe 
(bore must be undamaged)

•

Use bore gauge to check internal diameter of 
valve guide.

•

Calculate the nominal diameter of the valve 
guide:

Required diameter of valve guide = bore dia. + inter-
ference-fit value 
(0.015...0.044 mm/0.0006...0.0017 in).

•

Use an oversize 12.7 u6
(12.733...12.744 mm/0.5013...0.5017 in) valve 
guide.

•

Machine oversize valve guide to required diameter.

•

Slowly heat cylinder head to 200 °C (392 °F) in a 
suitable oven.

•

Immerse valve guide in liquid grinding paste.

•

Chill valve guide with dry ice.

e

 Attention:

The temperature must be –40 °C (–40 °F) immediate-
ly prior to insertion.

•

Place heated cylinder head flat on workbench or 
a similar surface.

•

Mount the chilled valve guide on 
dia. 5 mm (0.1969 in) drift, BMW No. 11 5 673.

•

Drive valve guides into cylinder head with no de-
lay.

•

Allow cylinder head to cool down to room tem-
perature, approx. 20 °C (68 °F).

•

Inspect bores of valve guides.

L

 Note:

Valve guides for repair purposes are produced with 
an internal diameter of 5.01 mm (0.1972 in) H7. 
In most cases, the bore is within the 
5.00 mm (0.1969 in) H7 tolerance range after press-
ing in. 
If the bore is too narrow, ream it out to size.