This week, let’s take a look at the 1974 Suzuki TM400L, one of about 20 fine motocross, enduro and trials motorcycles on display at the National Motorcycle Museum. If you plan a visit now or for later this summer before the Museum closes September 5, you can take in this TM400 plus hundreds of other motorcycles from about 1905 forward.

By 1974, Suzuki had already been through five production seasons of motocross bikes, had launched the TM400R Cyclone in 1971; the first mass produced Japanese motocrosser. Suzuki’s foray into production motocross machinery began with the rare blue and silver 1968 TM250, a twin port machine largely based on the CZ twin port design. Launching an open class machine really got the attention of American riders especially since Suzuki-mounted Joel Robert and Roger DeCoster had just won the 1971 250cc and 500cc World Championships. Soon after these wins, customers expected a production machine very similar to Robert’s championship machine design, the RN71, they could buy from their local dealer.

But the new for 1971 TM400 with its “feather trigger” power band and unforgiving handling proved to be unrideable for all but the best racers. The bikes were quite heavy, were prone to frame breakage and engine failure. So tuners tried heavier flywheels to smooth power delivery. They even relocated the engine down and a bit forward in the frame to improve handling.

So this open class Japanese motocrosser goes down in history as a bike with a peaky motor, poor suspension and a bit too much weight. But remember, it’s early, two years before Honda released their first two-stroke, the CR250 Elsinore. Over time the Japanese makers figured it out and competed strongly against the dominant European makers Bultaco, Husqvarna, Maico and CZ. By 1974, though still a handful, the TM400L was greatly improved over the original 1971 model. The Japanese brands’ dealer networks were larger, prices a bit lower, parts widely available and the machines often mechanically more dependable. All of these things helped motocross grow, introducing tens of thousands of young Americans to the sport.

This 1974 TM400 was donated to the National Motorcycle Museum by the late Tom White. Super passionate for the history of motocross, Tom was famous for his motorcycle parts and accessories company, White Brothers. Based in the Los Angeles area, later in life he built a fine collection of 1974 and earlier MX bikes, called his facility the Early Years of Motocross Museum. Once part of the recent temporary exhibition DIRT RIDING USA, Tom’s TM400 is now on display with other great off-road machines you can see when you visit.


    • Engine: Two-Stroke Single, Air-Cooled
    • Induction: Piston Port
    • Bore & Stroke: 82mm x 75mm
    • Displacement: 396cc
    • Carburetion: 34mm Mikuni
    • Lubrication: Oil Injection
    • Compression Ratio: 6.5:1
    • Horsepower: 40HP Rated
    • Clutch: Multi-Plate
    • Transmission: 5-Speed
    • Ignition: Electronic
    • Starting: Kick
    • Frame: Double Cradle, Steel
    • Suspension: Hydraulic Fork / Twin Shocks
    • Wheels / Tires: 3.00 x 21 / 4.00 x 18
    • Brakes: 5” Drum / 5.9” Drum
    • Wheelbase: 55 Inches
    • Weight: 230 Pounds Mfg, Dry / 250 Actual
13 replies
  1. steve szasz
    steve szasz says:

    I had a 71′ 400 TM i bought used. It was a monster. Left me broke down in the woods more times than I care to mention. Power band was quite small and a heavier flywheel did help but it was a challenge to ride. Sold it ind bought a Yamaha 400 IT.

  2. Motormike
    Motormike says:

    I raced a 250 Yamaha against them back in the day and won. The track was 90% creek beds, ditches, jumps, tight twisting turns and one long straight run.The Yamaha had a workable power band and handled well… , the Suzuki did going straight very fast with a narrow… on the pipe .. power band and poor handling. The big Suzuki would catch me at the of the straights…. Then I’d pull away… so big power in a narrow delivery and no handling was it’s track downfall.

  3. Super X man
    Super X man says:

    What a nice survivor of these bikes! Thanks for sharing and educating us. I was very young back in 1976 but remember the Suzuki CZ and Yamaha YZ “wars” in the marketplace.

  4. Merk
    Merk says:

    I raced a TM250 prior to entering the Marine Corps. When I got out I bought a TM400 & realized this Motorsickle could make you feel like novice no matter how great your skill level was. Insane power band.

  5. Joseph John Budick
    Joseph John Budick says:

    Had a old Rm 250 that had too much power and I am a six foot 200 pound nut, now I’m just enjoying my 10-speed TC 185. Also had a dt250 and a patent 175 jackpiner. Nothing Compares to the Suzuki MX horsepower.

  6. Eldon Seabert
    Eldon Seabert says:

    I was 13 years old when I bought my tm 400 bought another later on
    Loved the bike. Mean power lots of fun wish I still had them both..it could rooster tail ……loved the sound.

  7. David Murchie
    David Murchie says:

    I raced enduros in the SERA Enduro curcuit for years. I bought a 1974 TM 400 R new, my buddy Kip had one too. We rode the curcuit in LA, MS, Al, AR, FL on them. We also rode Hair Scrambles, Some Grass Tracks on HS Football fields and only a couple MX’s. My TM 400 was bone stock except for added 3# flywheel (to help tame the beast) and new rear shocks. Mind was a great bike never an issue, I flew through the woods (more one 1 wheel that two). High speed power wheelie at a twist of the throttle anytime, we would wheelie over everything that got in the way. Out of all the 30+ bikes over a life time and at 75 I would buy one today and ride it. I have a BMW 1250 GS, a KTM 890 Adv R and a KTM 500 exc-f Six Days now and ride all regularly.


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