Type Air-cooled horizontally-opposed transverse twin, with pushrod

operated overhead valves.

Dimensions Bore Stroke Capacity – Actual

R45 70.0mm (2.76″) 61.5mm (2.42″) 473.1cc (28.86 cu in)

R50 67.0mm (2.64″) 70.6mm (2.78″) 497.6cc (30.35 cu in)

R60 73.5mm (2.89″) 70.6mm (2.78″) 598.8cc (36.53 cu in)

R65, R65LS 82.0mm (3.23″) 61.5mm (2.42″) 649.2cc (39.60 cu in)

R75 82.0mm (3.23″) 70.6mm (2.78″) 745.3cc (45.46 cu in)

All 800cc models 84.8mm (3.34″) 70.6mm (2.78″) 797.1cc (48.62 cu in)

R90/6, R90S 90.0mm (3.54″) 70.6mm (2.78″) 897.8cc (54.77 cu in)

All 1000cc models 94.0mm (3.70″) 70.6mm (2.78″) 979.4cc (59.74 cu in)

Compression ratio (standard values quoted, some machines may have been fitted

with compression plates to reduce compression ratio from standard)

R45 9.2 : 1

R50 8.6 : 1

R60 9.2 : 1

R65, R65LS 9.2 : 1

R75 9.0 : 1

R80/7-40 kw version 9.2 : 1

R80/7-37 kw version,

all other 800cc models 8.2 : 1

R90/6 9.0 : 1

R90S 9.5 : 1

R100/7 9.0 : 1

R100 (UK) 8.2 : 1

All other 1000cc models* 9.5 : 1

*All US machines from 1980 models onwards, compression ratio was reduced

to 8.2 : 1.

Recommended engine speeds – rpm: Idle Max. Max.

permissible permissible

continuous

R45 R65 R65LS 800-1100 7300 7650

R50 R60/5 R60/6 R75/5 R75/6 R90/6 600-800 6500 7000

R60/7 800-1100 6500 7200

R75/7 800-1100 6500 7400

All 800cc models 800-1100 7200 7400

R90S 600-800 7000 7300

R100/7 800-1100 6800 7400

All other 1000cc models – UK –

all R100T R100S 1977,78 – US –

all except below 800-1100 7000 7400

All other 1000cc models – UK –

all except those above – US –

R100RS 1977 800-1100 7200 7400

Claimed engine output – DIN: Max. power Max. torque

(kw/hp@rpm) (Nm/lbf ft@rpm)

R45 26/35@7250 37.4/27.6@5500

R50 24/32@6400 38.3/28.3@5000

R60 29/40@6400 48.1/35.5@5000

R65 1978-80 models* 33/45@7250 50.0/36.9@5500

R65 1981 on models, R65LS* 37/50@7250 52.3/38.6@6500

R75 37/50@6200 58.8/43.4@5000

R80/7 – high comp. version 40/55@7000 62.5/46.1@5500

R80/7 – low comp. version 37/50@7250 56.6/41.8@5500

R80G/S R80ST* 37/50@6500 56.7/41.9@5000

R80RT 1983, 84 models* 37/50@6500 59.0/43.5@3500

R80, R80RT 85 on models* 37/50@6500 58.0/42.8@4000

R90/6 44/60@6500 73.0/53.9@5500

R90S 49/67@7000 76.0/56.1@5500

R100/7 44/60@6500 73.5/54.2@4000

R100T – US* 44/60@6500 74.6/55.1@5500

R100T – UK, R100S – UK ’77,

’78 R100S – US, R100RS – US

’78, ’79, R100RT – US* 48/65@6600 75.0/55.4@5500

R100 – UK 49/67@7000 72.0/53.1@5500

R100S – UK ’79, ’80, R100RS

– UK ’77 – ’80, R100RT – UK

’79, ’80 R100RS – US ’77* 51/70@7250 76.0/56.1@5500

R100CS R100RS R100RT – UK

models ’81 on* 51/70@7000 76.0/56.1@6000

*All models 1980 on – information applies only to UK models, not available

for US models.

Direction of engine rotation clockwise, looking from front of machine

Compression pressure R80G/S R80ST R80RT All other models

R80 ’85 on

Good over 9.0bar (131psi) over 10.0bar (145psi)

Normal 7.5-9.0bar (109-131psi) 8.5-10.0bar (123-145psi)

Poor below 7.5bar (109psi) below 8.5bar (123psi)

Valve clearances – engine cold Normal First 1000km (600m)

Inlet Exhaust Inlet Exhaust

/5,/6 0.15mm 0.20mm N/Av N/Av

(.006″) (.008″)

/7,R80G/S,R80ST,R80RT ’83-84 0.10mm 0.15mm 0.15mm 0.20mm

(.004″) (.006″) (.006″) (.008″)

R45,R65,R65LS,R80,R80RT ’85 on 0.10mm 0.20mm 0.15mm 0.25mm

(.004″) (.008″) (.006″) (.010″)

Valve timing – with 2.0mm (.08″) valve clearance, tolerance of +-2.5 degrees.

R50/5 R60/5 R60/6 ’76 R60/7 ’78

R60/6 up to 1975 R60/7 ’77

Inlet opens 40 deg ATDC TDC 6 deg BTDC

Inlet closes 40 deg ABDC 40 deg ABDC 34 deg ABDC

Exhaust opens 40 deg BBDC 40 deg BBDC 46 deg BBDC

Exhaust closes 40 deg BTDC TDC 6 deg BTDC

All R75 & R90, R80/7 R100/7 All other models

R100/7 R100S R100S

R100RS ’77 R100RS ’78

Inlet opens 10 deg BTDC 16 deg BTDC 16 deg BTDC

Inlet closes 50 deg ABDC 44 deg ABDC 44 deg ABDC

Exhaust opens 50 deg BBDC 56 deg BBDC 56 deg BBDC

Exhaust closes 10 deg BTDC 4 deg BTDC 4 deg ATDC

Valves

Head diameter: Inlet Exhaust

R45 R50 34mm (1.34″) 32mm (1.26″)

R60 R65 up to ’80 38mm (1.50″) 34mm (1.34″)

R65 ’81 on, R65LS 40mm (1.58″) 36mm (1.42″)

R75, all 800cc models 42mm (1.65″) 38mm (1.50″)

R90/6 R90S R100/7 42mm (1.65″) 40mm (1.58″)

All other 1000cc models 44mm (1.73″) 40mm (1.58″)

Head rim minimum thickness:

/5 /6 /7 1.0mm (0.0394″) 1.0mm (0.0394″)

R80G/S R80ST R80RT ’83-’84 0.8mm (0.0315″) 0.8mm (0.0315″)

R45 R65 R65LS 1.0-1.5mm 1.0-1.2mm

(0.0394-0.0591″) (0.0394-0.0472″)

Head maximum runout:

/5 /6 /7 0.025mm (0.0010″) 0.025mm (0.0010″)

R80G/S R80ST R80RT ’83-84 0.020mm (0.0008″) 0.020mm (0.0008″)

Overall length:

R50/5 102.6-103.0mm 102.1-102.5mm

(4.0394-4.0551″) (4.0197-4.0354″)

R45 R65 R65LS 98.8-100.2mm 99.1-99.5mm

(3.8898-3.9449″) (3.9016-3.9173″)

R60/5 R60/6 98.2-98.5mm 97.2-97.5mm

(3.8661-3.8780″) (3.8268-3.8386″)

R60/7 99.2-99.5mm 98.2-98.5mm

(3.9055-3.9173″) (3.8661-3.8780″)

All other models 98.4-98.8mm 98.4-98.8mm

(3.8740-3.8898″) (3.8740-3.8898″)

Valve Guides

Length overall:

/5 /6 except R90S 54mm (2.1260″)

R90S, /7 48mm (1.8898″)

R45 R65 R65LS 45mm (1.7717″)

R80G/S R80ST R80RT ’83-’84 44mm (1.7323″)

Outside diameter:

/5 /6 /7 R80G/S R80ST R80RT ’83-84 14.050-14.061mm (0.5532-0.5536″)

R45 R65 R65LS 14mm (0.5512″)

Inside diameter:

/5 /6 /7 8mm (0.3150″)

R45 R65 R65LS 7mm (0.2756″)

R80G/S R80ST R80RT ’83-84 8.000-8.015mm (0.3150-0.3156″)

Bore in cylinder head:

/5 /6 /7 R45 R65 R65LS 14mm (0.5512″)

R80G/S R80ST R80RT ’83-84 14.000-14.018mm (0.5512-0.5519″)

Interference fit in cylinder head:

/5 /6 /7 0.032-0.061mm (0.0013-0.0024″)

All other models N/Av

Oversizes available 0.1 & 0.2mm (0.004 & 0.008″)

Valve stem/guide standard clearance: Inlet Exhaust

R50/5 0.040-0.070mm 0.050-0.080mm

(0.0016-0.0028″) (0.0020-0.0032″)

R45 R65 R65LS 0.025-0.055mm 0.040-0.070mm

(0.0010-0.0022″) (0.0016-0.0028″)

R60 0.050-0.080mm 0.065-0.095mm

(0.0020-0.0032″) (0.0026-0.0037″)

All other models 0.050-0.080mm 0.050-0.080mm

(0.0020-0.0032″) (0.0020-0.0032″)

Inlet and exhaust valve stem/guide max. permissible clearance – measured

at top of guide:

R45 R65 R65LS 0.10mm (0.0039″)

All other models 0.15mm (0.0059″)

Valve seats

Outside diameter: Inlet Exhaust

R50/5 36.175-36.200mm 36.140-36.150mm

(1.4242-1.4252″) (1.4228-1.4232″)

R45 36.2mm (1.4252″) 36.2mm (1.4252″)

R60 39.175-39.200mm 39.175-39.200mm

(1.5423-1.5433″) (1.5423-1.5433″)

R65 R65LS 39.2mm (1.5433″) 39.2mm (1.5433″)

R75/5 43.175-43.200mm 43.140-43.150mm

(1.6998-1.7008″) (1.6984-1.6988″)

R75/6 R90/6 R90S 43.175-43.200mm 43.175-43.200mm

(1.6998-1.7008″) (1.6998-1.7008″)

R75/7 R80/7 R100/7 43.175-43.200m 43.134-43.200mm

(1.6998-1.7008″) (1.6982-1.7008″)

R80G/S R80ST R80RT ’83-84 43.175-43.200m 43.134-43.150mm

(1.6998-1.7008″) (1.6982-1.6988″)

All other 1000cc models 45.175-45.200mm 45.175-45.200mm

(1.7785-1.7795″) (1.7785-1.7795″)

Bore in cylinder head – inlet and exhaust:

R50/5 36.00-36.025mm (1.4173-1.4183″)

R45 36mm (1.4173″)

R60 39.00-39.025mm (1.5354-1.5364″)

R65, R65LS 39mm (1.5354″)

All 745cc 800cc 900cc, R100/7 43.000-43.025mm (1.6929-1.6939″)

All other 1000cc models 45.000-45.025mm (1.7717-1.7727″)

Interference fit in cylinder head: Inlet Exhaust

R50/5 R75/5 0.150-0.200mm 0.115-0.150mm

(0.0059-0.0079″) (0.0045-0.0059″)

R45 R65 R65LS N/Av N/Av

R75/7 R80/7 R100/7 R80G/S R80ST

R80RT ’83-’84 0.150-0.200mm 0.109-0.150mm

(0.0059-0.0079″) (0.0043-0.0059″)

All other models 0.150-0.200mm 0.150-0.200mm

(0.0059-0.0079″) (0.0059-0.0079″)

Seat angle:

Main seating face 45 deg

At combustion chamber 15 deg

At inlet/exhaust port 75 deg

Seat width:

Inlet 1.5mm (0.0591″)

Exhaust 2.0mm (0.0787″)

Seat oversizes available 0.2 0.4mm (0.0079 0.0168″)

Valve springs

Wire thickness 4.25mm (0.1673″)

Spring free length – approx:

Blue or green code 43.5mm (1.7126″)

Brown code 46.0mm (1.811″)

Spring force at test length:

At 37.6mm (1.4803″) 27.84-30.16 kp (61.30-66.5 lb)

At 28.5mm (1.1221″) 70.00-72.80 kp (154.30-160.5 lb)

Rocker gear

Arm ID -/5 18.032-18.059mm (0.7099-0.7110″)

Bush OD -/5 18.012-18.030mm (0.7091-0.7098″)

Arm/bush clearance -/5 0.002-0.047mm (0.00008-0.00185″)

Bush ID /5 14.532-14.559mm (0.5721-0.5732″)

Shaft OD /5 14.512-14.530mm (0.5713-0.5720″)

Bush/shaft clearance /5 0.002-0.047mm (0.00008-0.00185″)

Arm axial float:

R80 R80RT 1985 0.03-0.07mm (0.0012-0.0028″)

All other models Nil, but arm must be free to move