At the heart of the 1991 ATK 604 MX cross - motocross motorcycle, ATK features a 562 cc (34.3 cu in) air-cooled single cylinder, four-stroke configuration. In factory specification, peak output is rated at 40 HP (29.2 kW), transferring power to the rear wheel through a 5-speed gearbox and chain final drive. With a specific output of 71.2 HP per liter, the engine character is indicating a tractable, stress-free state of tune focused on everyday usability and broad torque delivery.
On the scales, the 604 MX measures 122.9 kg (271 lbs) dry, translating to a power-to-weight ratio of 0.33 HP/kg (3.07 kg per horsepower). Rider ergonomics and chassis geometry center around a 950 mm (37.4 in) seat height — reflecting a long-travel chassis stance that favors ground clearance and off-pavement control, combined with a 1,473 mm (58 in) wheelbase engineered for balanced agility and highway composure. The 17.41-liter (4.6 US gal) fuel tank supports practical everyday commuting and weekend road stints.
Specific Output
71.2 HP/L
Power-to-Weight
0.33 HP/kg (3.07 kg/HP)
Standover Height
950 mm (37.4 in)
Engine
Displacement562.0 ccm (34.29 cubic inches)
Engine TypeSingle cylinder, four-stroke
Engine DetailsSingle cylinder, four-stroke
Power40.0 HP (29.2 kW))
Compression9.8:1
Bore x Stroke94.0 x 81.0 mm (3.7 x 3.2 inches)
Valves/Cylinder4
Fuel SystemCarburettor. Mikuni TM 38 Flat Slide
Fuel ControlDouble Overhead Cams/Twin Cam (DOHC)
IgnitionCDI - Electric Advancing System
LubricationDry Sump System
CoolingAir
Transmission
Gearbox5-speed
Final DriveChain (final drive)
ClutchWet plate
Performance
ExhaustSupertrapp -Stainless-Steel
Chassis
Frame TypeNickel-Plated-Heat-Treated-Chromoly
Front SuspensionWP Adjustable USD
Front Travel300 mm (11.8 inches)
Rear SuspensionWP Multi-Adjuster Shock (Linkless)
Rear Travel330 mm (13.0 inches)
Wheelbase1473 mm (58.0 inches)
Ground Clearance343 mm (13.5 inches)
Wheels & Brakes
Front Tyre80/100-21
Rear Tyre120/90-18
Front BrakesSingle disc. 2-piston calipers
Front Brake Ø240 mm (9.4 inches)
Rear BrakesSingle disc. Disk mounted on front-sprocket . 1 piston caliper
Rear Brake Ø140 mm (5.5 inches)
Dimensions & Weight
Dry Weight122.9 kg (271.0 pounds)
Power/Weight0.3254 HP/kg
Seat Height950 mm (37.4 inches) If adjustable, lowest setting.
Use this page to compare this motorcycle by its real specifications, not only by model name. Focus on the details that affect fit, comfort, handling, range and ownership.
Power
Compare engine output with similar motorcycles if acceleration, highway use or two-up riding matters.
Seat Height
Check the seat height against your inseam and riding posture before choosing a motorcycle.
Weight
Compare weight carefully because it affects low-speed handling, parking and confidence.
Fuel Capacity
Fuel capacity helps estimate touring range and how often you may need to stop.
Brakes
Brake setup is worth comparing if you ride in traffic, mountains or with a passenger.
Suspension
Suspension details can matter for comfort, road feel and long-distance riding.
Transmission
Transmission and final drive affect maintenance, smoothness and everyday usability.
