Cylinder DR 75 Formula Uno – this is the sportiest 75cc DR cylinder for the Vespa V50 and PK50 models.
The cylinder has significantly more channel areas and exhaust cross section, and has, compared to all other DR cylinders for the small frame engines, the longest control angles (+13° exhaust compared to the very tame DR85).
In combination with the two generous secondary exhaust ports (which the cylinder still has, although otherwise claimed) the DR75 offers enough area to release the exhaust gases quickly from the cylinder even at higher speeds. This makes the cylinder particularly suitable for engines that are equipped with a very short gear ratio ex works. Especially the PK XL2 is grateful for any additional speed that can be obtained.
The DR thus also responds very well to larger carburettors such as the SHB 19/19 and other exhaust systems such as the LeoVinci or BGM Banana.
The cylinder is absolutely suitable for everyday use and reliable, despite all its speed capability, to which not least the coated piston plays its part. However, here too, as with any other conversion, the spraying (approx. 72-74 with SHB 16/16) and the heat value of the spark plug (NGK B8HS or Bosch W4AC) must be correct. The compression ratio of 10,7:1 is equal to the conventional 75/85cc DR cylinders.
An ideal addition is a carburetor kit with Ø19mm passage, a racing crankshaft and a 3.72 primary gear ratio. With this the Formula easily reaches the 70km/h mark.
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