Yamaha IT 425

Make Model	Yamaha IT 425
Year	1980
Engine	Two stroke, single cylinder, read valve
Capacity	425 cc / 25.9 cu-in
Bore x Stroke	85 x 75 mm
Cooling System	Air cooled
Compression Ratio	7.3;1
Induction	38mm VM38SS Mikuni carburetor
Ignition	CDI
Starting	Kick
Max Power	36.9 hp / 27.5 kW @ 6000 rpm (rear tyre
Max Torque	31 lb-ft / 4.23 kg-m @ 5500 rpm
Clutch	Wet, multi-plate
Transmission	5 Speed
Final Drive	Chain
Front Suspension	43mm Telescopic adjustable forks, 300mm wheel travel
Front Wheel Travel	250 mm / 9.8 in
Rear Suspension	Mono shock, adjustable spring preload and rebound damping, 300mm wheel travel
Rear Wheel Travel	250 mm / 9.8 in
Front Brakes	Drum
Rear Brakes	Drum
Front Tyre	3.00 -21
Rear Tyre	150/80 -18
Rake	29.5°
Trail	125 mm / 4.9 in
Wheelbase	1430 mm / 56.2 in
Ground Clearance	285 mm / 11.2 in
Dry Weight	111 kg / 244.7 in
Fuel Capacity	13.6 Litres / 3.5 US gal

The IT425 which for the first time brought 'professional'-type performance within the grasp of anybody able or willing to expend approximately £1,200 in pursuit of his chosen pastime of enduro racing (or fastgreen-laning).
Based on the YZ400 moto-crosser, with a triangulated rear frame and a single monoshock damper with variable loading, the IT (for International Trial) 425 had an air-assisted leading-axle front fork and very complete equipment, running even to a small headlamp powered from a flywheel generator.

The engine, however, tucked away in a lightweight, 56in-wheelbase chassis, justifiably took most attention on account of both its all-black good looks and its specification which, while keeping to nothing more outlandish than a five-port layout, with reed valve for induction, managed to churn out 46 bhp at 6,500 rpm, providing plenty of outright speed