The first motocross bike I raced was the Suzuki TM 250. That motorcycle was a beast for me as I was 14 years old and the main things I remember about the TM was absolutely NO low end power and then nothing but peel your eye-balls back power when it came up on the pipe or hit the powerband. The other thing was it refused to turn and had a crappy suspension but I raced it anyway for 3 years. The 250 was a handful but a older buddy who I rode with had the TM 400 and that motocross beast would eat you alive if you did not know what you were doing! I'd love to hear any stories from any reader's who owned, raced, or just rode the TM motocross bikes. What follows is some history on Suzuki's first production motocross bike introduced in America.

suzuki motocross bikes

Joel Robert was Suzuki’s first Motocross World Champion in 1970 winning the 250cc class and after this success Suzuki introduced a production motocross bike. The Suzuki TM400R was manufactured for the 1971 season and coincided with the signing of Roger DeCoster in October 1970. I remember going to a Trans Am race in Ohio and watching DeCoster race. He was SO SMOOTH it did not look like he was even trying yet he was the fastest guy on the track.

The following information traces the history of the Suzuki TM motocross bikes. Many people collect these original Suzuki motocross bikes and I wish I had hung onto mine. These early Suzuki motocrossachines are now a collectable motocross motorcycle as well as a reliable and competitive motocross bike in the Pre-74 classic motocross events.

Suzuki motocross bike



1971 Suzuki year code: R
Nicknamed the ‘CYCLONE’ the TM400R was the first Japanese production motocross bike 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 fiber 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. And woe to any motocross racer who tried to race the TM on a wet, muddy track without tapeing up the airbox! In stock form the airbox's paper filter drew any water from miles around and would shut you down faster than Oprah inhaling a carton of Twinkies!

It had Suzuki’s Posi-Force oil injection rather than the usual pre-mix used on most competition motocross 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 was not’t all used because the standard springs were to heavy. Rear suspension also was very stiff and only provided four inches of travel. Several companies came out with rear suspension up grades to increase the rear travel but most were junk. I tried one on my TM and I think it was called the unilever? I might be wrong about that name but anyhow it did add a couple more inches of travel to the rear suspension but it was so poorly made it made the bike even more squirrelly than it already was.

400 TM

It was very powerful and unlike the Suzuki factory ‘Works’ bikes of DeCosters it didn’t handle, in fact it was totally different to the factory motocross bikes and more suited to the open type racing or desert races in the USA. For the more serious motocross 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 color was Chrome Orange with a black stripe running under the badge horizontally.