BMW MOTORCYCLE ENGINE BMW HEAVYBIKE ENGINE
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
