| MODEL | YAMAHA XJ 400S DIVERSION 1991 |
| Year | 1991 |
| Engine Type | Four stroke, transverse four cylinder, DOHC, 4 valves per cylinder |
| Displacement / Capacity | 399 cc / 24.2 cu in |
| Bore X Stroke | 55 x 47 mm |
| Compression Ratio | 10.7:1 |
| Cooling System | Air cooled |
| Max Power | 30.8 kW / 42 PS @ 10000 rpm |
| Max Torque | 3.5 kgf-m / 25.3 lb-ft @ 7000 rpm |
| Ignition | CDI |
| Induction | 4x 30 mm CV carburettors |
| Start System | Electric |
| TRANSMISSION SPECS | |
| Lubrication | — |
| Gear Box | 6 speed |
| Clutch | — |
| Final Drive | Chain |
| CHASSIS SPECS | |
| Frame | — |
| Front Suspension | Telescopic forks |
| Rear Suspension | Dual shocks, preload adjustable |
| Front Brakes | Single disc, 2 piston caliper |
| Rear Brakes | Single disc, 2 piston caliper |
| DIMENSION SPECS | |
| Overall Length | — |
| Overall Width | — |
| Overall Height | — |
| Seat Height | — |
| Wheelbase | — |
| Ground Clearance | — |
| Dry Weight | 178 kg / 392 lbs |
| Wet Weight | — |
| WHEEL SPECS | |
| Front Tyre | 110/70-17 |
| Rear Tyre | 130/70-18 |
| FUEL SYSTEM | |
| Fuel Capacity | 18 Litres / 4.7 US gal |
| Fuel Consumption | — |
| Top Speed | — |
The XJ400S Diversion was the small-capacity sibling of the 600 Diversion, a half-faired, air-cooled four with twin rear shocks. It was a friendly, practical all-rounder rather than a sportsbike, with 17 and 18 inch wheels and a disc at each end.
