Stage6 R/T 70cc racing cylinder kit for Derbi D50B0/1 2-stroke moped engines.

The cylinder that has been breaking records! It set new best times in the Italian Open Cup and also broke the 6 second barrier in scooter drag racing. Regarding transfer port layout, Stage6 has maintained GP standards, refraining from cross section reducing 7 or 8 port designs. After all, "more" isn't necessarily "better". The 47.6 mm bore conforms to the rules of most 70 cc racing classes. The patented modular construction allows for quickly mounting the cylinder to different engines using adaptors. Sealing between adaptor plate and cylinder is realized via a Viton® O-ring; this makes the tedious cleaning of sealing surfaces and replacing gaskets unnecessary. Once the adaptor plate has been mounted and adjusted via gaskets, it won't have to be readjusted later. The CNC milled adaptor plate bolts to the engine case and accepts the cylinder via the external studs. The construction of the R/T 70cc cylinder doesn't use any continuous studs, so the design of exhaust and transfer ports isn't subject to the restrictions that conventional racing cylinders face, and further tuning and porting reserves are available. Particular attention has been paid to the cylinder's thermal properties.

The CNC milled inner cylinder head is bolted at five points, each of them thermally stabilized by its own cooling pocket. Thus the critical areas at the studs that tend to lead to piston seizures have been eliminated. The flange firmly connects the cylinder to the exhaust via three bolts, minimizing the leakage of fuel residues. The kit includes an exhaust flange that fits the Stage6 R/T exhaust and installation instructions.

Please note: To mount this kit you will need to machine the cases to accept the cylinder. (Instructions are included in the kit)

Skirt dimensions:
Diameter: 56.7mm
Length: 10mm

Stage6 recommend this kit be used with their R/T exhaust systems, a 28mm PWK type carb with matching intake, an upgraded clutch and adjustments to the gearing and ignition with an inner rotor ignition system.

A high quality racing crankshaft with standard length stroke (39mm) with standard length (85mm) conrod is also required.

Stage6 S6-7519303