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Suzuki TM400, TM250
1971-1975
I have tried to tell the model history of the Suzuki TM 250 and 400 models on this page as the know it.
I would be grateful of any contributions sales brochures, magazine ads,
magazine articles, pictures, specs, facts, corrections etc. Please scan the material
in JPEG format (large enough that all the details are visible) and send
them to me. Please tell me the source and the publication date if possible.
If you send me pictures of your own bike, please follow these
instructions. |


A detail from a 1972 TM-250 J & TM-400
advertisement. American motorcross champion The guys at the picture
are John De Soto (left) and his brother Don. Click the image to
view the full brochure page. I thank Gary Jesswein for providing
me the brochure scan! |
SUZUKI
TM MOTOCROSS MODELS INTRODUCTION
Joel Robert was Suzukis first Motocross World Champion in
1970 winning the 250cc class and after this success Suzuki introduced
a production motocrosser. The Suzuki TM400R was manufactured for
the 1971 season and coincided with the signing of Roger DeCoster
in October 1970.
The following information traces the history of the Suzuki TM
range and were possible have included original Suzuki brochures
to help people identify and restore TMs. These early Suzuki
motocrossers are now a collectable machine as well as a reliable
and competitive bike in the Pre-74 Classic Scramble events.
TM400R (1971)
Nicknamed the CYCLONE the TM400R was the first Japanese
production motocrosser to be mass-produced. The huge 82.5mm bore
piston turned out 40 bhp at 6,500 rpm and along with the fan-finned
cylinder head it had a compression ratio of 7.3 : 1. The crankshaft
halves were not full circle type as fitted to most two-stroke
engines and made the engine rev more; one answer was to fit aftermarket
flywheel weights made by Competition Dynamics in the USA. The
clutch was based on the T500 road bike with seven fibre drive
plates and seven metal driven plates it was operated by a rack
and pinion type mechanism. A five-speed gearbox provided transmission.
Carburation was provided by a Mikuni 34mm carburettor featuring
a fuel trap around the main jet, developed to keep the float level
more constant by keeping the fuel in the trap area. Air filtration
was by a large capacity, dry paper element housed in an airbox
under the seat.
It had Suzukis Posi-Force oil injection rather than the
usual pre-mix used on most competition bikes of the time, the
two stroke oil tank was situated behind the right hand number
plate. Kokusan Denki provided the sparks with their new pointless
electronic ignition (PEI) that had an automatic spark advance
curve from eight degrees at 2000 rpm to 28 degrees at 5000 rpm.
The front forks had seven inches of travel but this wasnt
all used because the standard springs were to heavy. Rear suspension
also was very stiff and only provided four inches of travel.
It was very powerfull and unlike the Works bikes of
DeCosters it didnt handle, infact it was totally different
to the factory racers and more suited to the open type racing
or desert races in the USA. For the more serious competitor specialist
frame manufacturers produced frames to help the handling problems,
Eric Cheney in the UK and Red Line Engineering in the USA were
two such companies. Folding footrests were made from fabricated
steel. The fuel tank had a steel twist type cap with air breather
and badges that screwed on, the colour was Chrome Orange (Suzuki
colour code 184) with a black stripe running under the badge horizontally.
TM400J (1972)
Virtually identical to the 1971 model apart from the colour which
was now Philolina Yellow (Suzuki colour code 163) so it was more
in keeping with the works bikes. |
1972 TM-250J & TM-400J magazine
ad. Click to enlarge.
|
TM-400K
(1973)
Again it was very much the same as the 1971 & 1972 models
with odd changes. The air filter was now a more washable foam
element. Footrests were now cast steel folding type. A different
frame, forks, suspension units and swinging arm were all fitted
in an aim to help the handling. The fuel tank had Suzuki stickers
instead of badges and a blue/white stripe went round the back
of the tank where the letters TM appeared. |

1973 TM-400K sales brochure.Click to enlarge.
TM400L
(1974)
Much the same as the 1973 model, the L had straight type finning
on the cylinder head and internally had been altered to reduce
the compression ratio to a more useful 6.8:1. The front sprocket
cover was now fitted with three holes for mud to escape from rather
than the earlier type that had two diagonal slits. The exhaust
system now had a rear silencer fitted to help muffle the noise.
Suspension units were a newer type. The fuel tank now had dark
green/white stipes that did a U round the rear of the tank.
TM250J
(1972)
The new TM250J and was knicknamed the CHAMPION, After
the RH71 works 250 ridden by World Champion, Joel
Robert. It was based very much on the TS250 trail bike and shared
many engine parts including the figure of eight type Magneto cover
and clutch operated through a worm and push rod arrangement. The
sprocket cover was fitted with three diagonal slits and all the
cases were finished in a satin matt black colour. The compression
ratio was 7.5:1 and had a fan type cylinder head; the piston bore
size was 70mm.
An exhaust system with no rear silencer certainly made the machine
sound good and courtesy of a five-speed constant mesh gearbox
it produced 30 bhp at 7,500 rpm. A 34mm Mikuni carburettor was
fitted and foam air filter was boxed under the seat.
Ignition was by PEI (pointless electronic ignition). Suzukis
own Posi-Force lubrication system was used with the two-stroke
oil tank being fitted under the right hand side number plate.
Footrests were folding fabricated sheet steel type. The fuel tank
was in yellow (Suzuki colour code 163, Aspen Yellow ! ), it had
a black stripe following the outer shape of the tank and had Suzuki
badges screwed on top of the stripe. The tank cap was a steel
twist type with a breather pipe. The wheels had aluminium alloy
rims with a 300x21 knobbly tyre on the front and a 400x18 fitted
to the rear. The total weight of the bike was a very competitive
220 lbs dry. |
1972 TM-250J & TM-400J
brochure page. Click to enlarge.
|

1972 TM-250J sales brochure.
Click to enlarge.
TM250K
(1973)
Very similar to the 72 model the K had the following changes.
New type clutch cover with a rack and pinion type clutch operation,
although the magneto and sprocket covers were still the same.
The folding footrests were now the later type cast steel. Rear
suspension units and swinging arm were the same as the predecessor.
The fuel tank had Suzuki stickers instead of badges and a blue/white
stripe went round the back of the tank where the letters TM appeared.
|
1973 TM-250K sales brochure.Click to enlarge.
TM250L
(1974)
Much the same as the 72/73 models the L had these
few differences. Straight type finning in the cylinder head. Smaller
type magneto cover and a sprocket cover peppered with seven holes
to clear mud easier.
A rear silencer was now fitted to the exhaust to lower the decibels.
Front forks, suspension units and swinging arm were all uprated.
The rear mudguard now bolted on to the rear frame loop. The fuel
tank now had dark green/white stipes that did a U round the rear
of the tank.
TM250M
(1975)
Just a few changes over the previous models for the M model. The
gearbox had some gears with different ratios. Suspension units
were again different. The fuel tank was all yellow with the Suzuki
logo written over a rising sun type design. |
More:
Suzuki TM series
More: All
Suzuki models
Source: http://www.crooks-suzuki.com/tm.html
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