To get the maximum out of your set-up, we recommend to get a matching cylinder and crankshaft. The kit includes: – Cylinder Kit Bidalot Racing Factory WR 90cc: Bidalot reworked and improved their already powerful Racing Factory kits. The cylinder has 7 transfer ports, the bridged exhaust port is relieved and supported by boost ports. Bore diameter is 50.5mm now. The cylinder head is made of HQ aluminium, the cylinder head cover is also CNC-machined and comes with a stunning looking matte black finish. – Crankshaft Bidalot Racing Factory 44.9mm stroke – 90mm connecting rod: Full-circle racing crankshaft with superior balancing that was built to resist high speeds. Combining those two components will result in a displacement of precisely 89.93cc – awesome!