Vintage Motocross: 1965 CZ Twin Port

Vintage MX Motorcycles

In the annals of motocross, the CZ Twin Port stands out as an early exotic race bike. The 250cc (as well as the 360cc) elevated the sport to new heights with a hint of how new exotic metals could transform the machinery.

Using magnesium in many of the CZ’s components (primarily the drum brake hubs and engine cases) brought the 250cc bike’s weight down to a claimed 214 pounds.

The bike had an exceptionally simple yet stunning aura, set off by the peanut tank – with the legendary CZ insignia – and the low slung expansion chambers (no rules yet about excessive decibels meant these machines could run without silencers).

However, what really intrigued was the single cylinder 2-stroke engine’s use of a twin exhaust port. Twin chrome header pipes exited the air-cooled cylinder and split the frame’s front downtube, the pipes running underneath the bike to exit on either side of the swingarm.

Whether the added exhaust volume truly added to the performance (a reported 27 hp) has never been truly understood, but as a psych-out you couldn’t find anything quite as bitchin’ (yes, I said bitchin’) as this bike.

In the hands of Belgian motocross sensation Joel Robert, the twin port CZ won the 250cc MX World Championship in 1964, and again in 1965 with Russian Victor Arbokov. Other notable riders who made their mark on the Czech twin port bike were Roger DeCoster and Dave Bickers.

The CZ had fixed bars for footpegs-which offered virtually no traction-and the now famous welded on clutch and brake lever perches (a CZ trademark). The transmissions were 4-speeds and had the famous clutch arm (look at the picture detail of the motor) which Joel reportedly used to cram his boot into so he could put the bike in gear for the old hand on the helmet/neutral starts in MX.

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