14 August. Friday 2026
ATK 604 MX - 1991 Specifications and Reviews
The 1991 ATK 604 MX is a competitive motocross machine powered by a 562cc single-cylinder four-stroke engine producing 40 horsepower. Built for serious off-road racers, it features a five-speed transmission, DOHC valve train, and dry-sump lubrication for reliable performance in demanding conditions. Known for its lightweight construction and nimble handling, this Austrian-built bike excels in technical terrain and tight courses.
1991
General information | |
| Category | Cross / motocross |
| Year | 1991 |
| Model | ATK 604 MX |
| | |
Engine and Transmission Specifications | |
| Exhaust system | Supertrapp -Stainless-Steel |
| Clutch | wet plate |
| Transmission type,final drive | Chain |
| Gearbox | 5-speed |
| Cooling system | Air |
| Lubrication system | Dry Sump System |
| Ignition | CDI - Electric Advancing System |
| Fuel control | DOHC |
| Fuel system | Carburettor. Mikuni TM 38 Flat Slide |
| Valves per cylinder | 4 |
| Bore x stroke | 94.0 x 81.0 mm (3.7 x 3.2 inches) |
| Compression | 9.8:1 |
| Power | 40.00 |
| Engine type | Single cylinder, four-stroke |
| Capacity: | 562.00 ccm (34.29 cubic inches) |
Brakes, suspension, Frame and wheels | |
| Rear brakes diameter | 14 mm (0.6 inches) |
| Rear brakes | Single disc. Disk mounted on front-sprocket . 1 piston caliper |
| Front brakes diameter | 24 mm (0.9 inches) |
| Front brakes | Single disc. 2-piston calipers |
| Rear tyre dimensions | 120/90-18 |
| Front tyre dimensions | 80/100-21 |
| Rear suspension travel | 330 mm (13.0 inches) |
| Rear suspension | WP Multi-Adjuster Shock (Linkless) |
| Front suspension travel | 300 mm (11.8 inches) |
| Front suspension | WP Adjustable USD |
| Frame type | Nickel-Plated-Heat-Treated-Chromoly |
Physical measures and capacities | |
| Oil capacity | 2.30 litres (0.15 quarts) |
| Fuel capacity | 17.41 litres (4.60 gallons) |
| Wheelbase | 1,473 mm (58.0 inches) |
| Ground clearance | 343 mm (13.5 inches) |
| Overall width | 860 mm (33.9 inches) |
| Overall length | 1,473 mm (58.0 inches) |
| Seat height | 950 mm (37.4 inches) If adjustable, lowest setting. |
| Power/weight ratio | 0.3254 HP/kg |
| Dry weight | 122.9 kg (271.0 pounds) |
| | |
Other specs | |
| Maintenance | Find parts, fluids, filters, maintenance tools and service items on eBay |
| Color options | White |
| Starter | Electric & kick |
Performance Profile & Rider Fit
40 hp
Peak Power
Best For
Track40%
City15%
Cornering70%
Daily Riding10%
Touring10%
Passenger5%
Rider Profile
| Best For | This is a purebred early-90s big-bore motocrosser best suited to experienced off-road riders who know how to manage a punchy, torquey big single. |
| Purpose | Built purely for motocross and open-terrain competition, not for street use or commuting. |
| Rider Fit | At under 123kg dry with a tall 950mm seat, it rewards an active, fit rider who can stand and shift weight aggressively, though its light weight makes it manageable for smaller riders too. |
| Character | Raw, torquey, and mechanical in feel, with premium WP suspension and a big air-cooled single that delivers old-school four-stroke motocross character rather than modern refined power. |
| Not Ideal For | Not suitable for anyone wanting a comfortable, low-maintenance daily rider, a passenger-friendly bike, or a machine capable of highway touring. |
Character map is an editorial estimate based on this bike's specifications, not a lab-tested measurement.
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