Yamaha GX 750 Sport (1978-79) vs Yamaha RS 100 (1978-79) vs Yamaha XS 650E (1978) vs Yamaha TT 500 (1978-81) vs Yamaha RD 250 (1978) vs Yamaha XS 750 Special (1978) vs Yamaha SR 400 (1978-80) vs Yamaha XT 500 (1978) vs Yamaha RD 125 (1978)

Comparison technical specifications

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Make:	Yamaha	Yamaha	Yamaha	Yamaha	Yamaha	Yamaha	Yamaha	Yamaha	Yamaha
Model:	GX 750 Sport	RS 100	XS 650E	TT 500	RD 250	XS 750 Special	SR 400	XT 500	RD 125
Years:	1978-79	1978-79	1978	1978-81	1978	1978	1978-80	1978	1978
Engine:	Four stroke, transverse three cylinder. DOHC	Two stoke, torque induction, single	Four stroke, parallel twin cylinder, SOHC, 2 valves per cylinder.	Four stroke, single cylinder	Two stroke, torque induction, parallel twin	Four stroke, transverse three cylinder, DOHC, 2 valves per cylinder.	Four stroke, single cylinder, SOHC, 2 valves per cylinder.	Four stroke, single cylinder, SOHC, 2 valve	Two stroke, parallel twin
Capacity:	747 cc / 45.5 cu-in	97 cc / 5.9 cu-in	653 cc / 39.8 cu in	499 cc / 30.4 cu-in	247 cc / 15.0 cu-in	747 cc / 45.6 cu in	399 cc / 24.3 cu-in	499 cc / 30.5 cuin	124 cc / 7.6 cu-in
Bore x Stroke:	68 х 68.6 mm	52 x 45.6 mm	75 x 74 mm	87 х 84 mm	54 х 54 mm	68 х 68.6 mm	87 х 67.2 mm	87 х 84 mm	43 х 43 mm
Cooling System:	Air cooled	Air cooled	Air cooled	Air cooled	Air cooled	Air cooled	Air cooled	Air cooled	Air cooled
Compression Ratio:	8.5:1	7.0 : 1	8.4:1	9.0 :1	6.7:1	9.5:1	8.5:1	9.0 :1	6.8:1
Induction:	Mikuni Thorex SU type BS34	VM20SH carburetor	2 x Mikuni BS38 carburetors	38mm Mikuni	2x Mikuni VM28 SC carburetor	3 x Mikuni BS34-II constant velocity carburetors	BSR33 carburetor	32mm Mikuni VM32SS carburetor	2x 18mm Teikei carburetors
Starting:	Electric	Kick	Electric and kick	Kick	Kick	Electric	Kick	Kick	Kick
Max Power:	67 hp / 50 kW @ 7000 rpm	11 hp / 8.1 kW @ 8500rpm	39.5 kW / 53 hp @ 7200 rpm	27 hp / 19.7 kW @ 5900 rpm	30 hp / 22.3 kW @ 7500 rpm	50.4 kW / 69 hp @ 8500 rpm	27 hp / 17.1 KW @ 7000 rpm	32 hp / 23.5 kW @ 6500 rpm	17 hp / 12.4 kW @ 8500 rpm
Transmission:	5 Speed	5 Speed	5 Speed	5 Speed	6 Speed	5 Speed	5 Speed	5 Speed	5 Speed
Final Drive:	Shaft	Chain	Chain	Chain	Chain	Shaft	Chain	Chain	Chain
Front Suspension:	Telescopic forks	Telescopic forks	Telescopic forks	Telescopic fork	Telescopic forks	Telescopic forks, adjustable, 36 mm	35mm Telescopic fork	Leading axle coil spring fork	28 mm telescopic forks
Rear Suspension:	Dual shocks	Dual shocks	Dual shock absorbers	Swinging arm	Dual shocks	Dual shocks swing arm, 5-way preload adjustable	Dual shocks, 5-way adjustable preload	Swing arm adjustable preload	Dual rear shock pre-load adjustable
Front Brakes:	Single disc	Drum	Twin hydraulic discs, 267 mm	Drum	Single 267mm disc	2 x 267mm Discs	Single disc	Single 160mm drum	Single240mm disc
Rear Brakes:	Single disc	Drum	Drum	Drum	Single 267mm disc	Single 265mm disc	Drum	Single 150mm drum	130 mm Drum
Front Tyre:	F3.25-19	2.75-18	3.50H-19 4PR	3.00-21	3.00S-18-4PR	3.25-19	3.50-19	3.00-21	2.75-18
Rear Tyre:	4.00-18	3.00-18	4.00H-18 4PR	4.60-18	3.50S-18-4PR	4.00-18	4.00-16	4.00-18	3.00-18