Fire Road Flyer: 1971-1979 Suzuki TS400 Apache

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1971-1979 Suzuki TS400 Apache.
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1970-1975 Kawasaki F5 Bighorn 350.
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1975-1979 Yamaha DT400.

Suzuki TS400 Apache
Years produced: 1971-1979
Power: 34hp @ 6,000rpm (claimed)
Top speed: 81mph (period test)
Engine: 396cc air-cooled piston-port 2-stroke single
Transmission: 5-speed, chain final drive
Weight (wet): /MPG 292lb (TS400J), 313lb (TS400L)/ 44mpg (TS400J), 23-25mpg (TS400L)
Price then/now: $952 (1972 ,TS400J); $1,220 (1975, TS400L)/$1,000-$2,500

Until the late 1960s, the typical “dual-sport” machine was a street bike wearing parts that made minimal concessions to off-highway riding and were chiefly cosmetic. The 1968 Yamaha DT-1 changed all that. Suddenly, Triumph TR6Cs, Honda CL350s and BSA Victors looked heavy, clunky and stodgy — which they were by comparison. It didn’t take long for the other Japanese manufacturers — especially Suzuki — to catch on. With six world motocross championships in four years from 1970-1973 with Joel Robert and Roger De Coster, Suzuki emphatically demonstrated the company’s dirt-bike chops, and successfully translated the technology into their over-the-counter scramblers and dual-sport bikes.

Top of the 1971 dual-sport range was the TS400J, a street/dirt bike based on the TM400 customer motocrosser. It featured a 396cc single-cylinder, air-cooled 2-stroke engine with conventional piston porting, like the TM, but with a heavier flywheel, milder port tuning and smaller 32mm Mikuni carburetor. Straight-cut gears drove the 14-plate wet clutch and 5-speed transmission. Ignition was electronic, and lubrication was by Suzuki’s Crankcase Cylinder Injection (CCI) system. The single downtube steel tube frame carried a non-adjustable telescopic fork at the front and a swingarm and dual shocks at the rear. The tires were 3.25 x 19 inches at the front and 4 x 18 inches at the back. (The TM used a 3 x 21-inch front.) The addition of battery and full lighting equipment, a swap from alloy wheel rims to steel, and a steering damper contributed to the TS400’s extra 47 pounds over the TM.

The result was a bike that “works surprisingly well” on the street, Cycle World said. “On mountain roads, fast bends are a breeze and a good pace can be maintained… the Apache can be ridden quickly and for a considerable distance to a rider’s favorite set of fire roads,” CW’s testers said, though noting that vibration “becomes a little heavy around 5,000rpm.” CW also liked the flexible plastic fenders, washable air filter and simple maintenance schedule (refilling the oil tank daily). Other than that, oil the cables periodically and adjust the rear chain often.

It was offroad riding where the Apache almost literally fell down. “Suzuki engineers turned a relatively light, overpowered 400MX into an overweight front-heavy sled,” CW said. Though testers liked the broad powerband, slick-shifting transmission, in-gear kickstart with automatic decompressor (for quick restarting after a stall), and good brakes, a number of factors conspired to make the Apache a handful in the woods. The smaller front wheel would “wash out” easily in turns and plowed into sand; a shorter fork meant less travel than the TM and a more forward weight bias; and soft, lightly damped rear shocks meant the rear wheel getting airborne too easily, leading to front-wheel landings, “one of the worst situations an off-roader faces,” CW said.

Cycle magazine liked the TS400J better, in spite of some minor electrical issues: “It’s a phenomenal street bike if your vibration threshold is high. It’s a good enough dirt bike that… we’d enter the 500-mile Greenhorn Enduro… all you could want is better suspension.”

For 1975, Suzuki announced the Apache TS400L, with a new dual downtube frame (still with the same geometry of the J), a taller 3 x 21-inch front wheel, and a revised engine with helical-gear primary. Cycle’s tester noted: “Changes to the intake to reduce noise seem to have adversely affected power delivery.” The engine “refused to run smoothly under steady throttle at any speed… a mismatch of carburetion, port timing and exhaust.” Was the TS400L an early victim of EPA-itis?

Noting that the new frame carried the engine much higher, the tester was not too impressed with the TS400L’s handling, on-road or off. “With the rise of the engine comes increased foot peg and saddle heights, which lessen stability at cross-country speeds.” And in Cycle Guide’s dual-sport shootout, “The TS400 had more jetting problems than we had time for… the Suzuki not only got the worst mileage (as little as 60 miles to a tank), but it never realized its full power potential.” Summed up Cycle: “[Suzuki]… made the TS400L a mediocre street machine as well as an unacceptable dirt bike. In the process we lost an old friend.” MC

Contenders: Alternatives to Suzuki’s big-bore 2-stroke offroader

1975-1979 Yamaha DT400
Years produced: 1975-1979
Power: 27hp @ 5,000rpm (claimed)/81mph (period test)
Engine: 397cc air-cooled 2-stroke single
Transmission: 5-speed, chain final drive
Weight/MPG:290lb (wet)/35mpg
Price then/now: $1,371 (1975)/$1,000-$3,000

A direct descendent of the DT-1, the 1975 DT400B grew from the 351cc RT-1 and DT360A (“the best all-round big-bore dirt bike in town,” according to Cycle). With a 5mm bore increase for 397cc, “The DT400B is notably better,” they said in November 1974, calling the DT400’s mill “the best enduro engine regardless of displacement from the Orient.”

Like the DT360, the 400 used a reed-valve intake, but had a larger carburetor and new radial-fin cylinder head, eliminating the mid-range detonation that Cycle magazine experienced with the 360. In spite of an automatic decompressor, Cycle found the 400 difficult to start, though Cycle World perfected the technique: two or three kicks through with the ignition off, then one with the ignition on usually got it going.

CW found the suspension gave a harsh ride on rough ground, where fork action deteriorated significantly. “As long as you don’t require the suspension to react too fast or too often, it works just fine.” Summing up, said CW, “As a play bike that can be ridden on the street, it is a good buy. It is just as heavy and handles no better than its competition, but it does have an engine with the best possible power characteristics… that lifts the total motorcycle from mediocrity to the head of its class.”

1970-1975 Kawasaki F5 Bighorn 350
Years produced: 1970-1975
Power: 33hp @ 6,500rpm (claimed)/85mph (period test)
Engine: 346cc air-cooled 2-stroke single
Transmission: 5-speed, chain final drive
Weight/MPG: 278lb (wet)/38mpg
Price then/now: $1,371 (1975)/$1,000-$2,000

Unique in its class, the Kawasaki F5 offered a front fork that was adjustable for spring preload, height and trail — the Hatta fork legs could be rotated, offering three different axle locations; ahead, behind, or along the fork axis, shortening or lengthening the wheelbase 2 inches total. That meant the Bighorn’s fork could be tuned for enduro, desert or fire-road riding. “There was not a situation or obstacle that could cause them to top or bottom,” Cycle Guide wrote.

Into the F5’s dual-cradle frame went a rotary-valve 2-stroke single, with an available “Power-Pak” accessory option giving 45 horsepower, but at the expense of low-rpm torque. “The easy-to-handle low-end power of the stock machine is one of the things Cycle World staffers liked best about the Bighorn,” wrote that magazine. That said, the same testers complained about a hard-to-find neutral when stopped with the engine running and false neutrals when shifting under load. Revisions for the 1972 F9 model included revised shifting forks that avoided false neutrals.

The F5 ran on 3 x 21-inch front and 4 x 18-inch rear wheels with alloy rims and fenders. Drum brakes offered “good stopping power,” on the street, but were also “controllable” on loose surfaces, CW wrote. “We would not hesitate to recommend the F5 to both the novice and the expert, for it will satisfy both,” CW concluded.

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