The Viper SK250S is a 250cc single cylinder Superkart engine.
The cylinder is reversed (exhaust out-of-the-back) with a front mounted carburettor feeding into the crankcase via a reed induction system.
The crankshaft is fully shrouded with just a slot through to the top end for the connecting rod.
It has a bore and stroke of 68.0 x 68.8mm and a rod length of 128mm
The crankcases are machined from billet aluminium. It has a gear driven counterbalance shaft with an internal balance weight on the right and an external balance weight on the left.
The cylinder has 3 exhaust ports and 5 transfer ports.
Gearbox, clutch and selector mechanism are taken from the 2002-2007 Honda CR250 and in standard (UK) format it is a 5-speed with alternative gearbox ratios. Our 6-speed gearbox can also be fitted if local regulations allow.
The ignition is Viper Racing’s own digital programmable ignition that runs off the 2002-2007 Honda generator, however, many ignition options are possible.