ENGI
N
E
4
www.betamotor.com
type
Single cylinder, 4-stroke, liquid-cooled with countershaft
and electric starting
Bore x stroke RR 350
88x57,4
Bore x stroke RR 390
88x63,4
Bore x stroke RR 430
95x60,8
Bore x stroke RR 480
100x60,8
Displacement [cm³] RR 350
349,1
Displacement [cm³] RR 390
386
Displacement [cm³] RR 430
431
Displacement [cm³] RR 480
478
Compression ratio RR 350-390-430-480
13,19:1
12,5:1
12.3
11,9:1
Valve gear
4 valves
tRANSMISSIoN
RR 350
RR390
RR430
RR480
Primary transmission
28/76
28/76
31/73
31/73
1st gear ratio
12/31
12/31
12/31
12/31
2nd gear ratio
15/28
15/28
15/28
15/28
3rd gear ratio
19/28
19/28
19/28
19/28
4th gear ratio
20/24
20/24
20/24
20/24
5th gear ratio
27/27
27/27
27/27
27/27
6th gear ratio
28/24
28/24
28/24
28/24
tECHNICAL fEAtURES of ENGINE