NSR300

The NSR300 comes about as a result of third parties fitting two NSR150R barrels onto an NSR250R engine. (2 x 150cc = 300cc)

The bore and stroke of the NSR150R is 59mm x 54.5mm

The bore and stroke of the NSR250R is 54mm x 54.5mm

So, very simply put, it is effectively a 5mm oversize re-bore.

TYGA Performance have developed a kit for this conversion, with a few options.

Many others continue to dabble with this idea with varying degrees of success.