The Dryvtech utilises a 250cc 2 stroke made specially for the job, the crankcases and covers being machined from solid aluminium billet.  The barrel and head were cast up using a Maico barrel as a starting point however the ports were designed and made in a lower state of tune.  The crankshaft is a shortened and lightened Maico unit using the standard piston.  Drive from the crank to the pump is by a custom made geartrain as the donor engine used a chain primary drive.  These gears are matched up to the pump drive shaft (made from titanium) so that the pump runs all the time that the engine runs - it can't be disconnected.  This picture shows the left-hand side of the engine with the transmission pump clearly visible nestled behind it.

The exhaust is a true expansion chamber in that the exhaust gases don't actually pass through it - it is a resonance chamber only.  This picture mainly shows the 'expansion chamber'- the actual exhaust gasses exit through another pipe which continues where the pipe changes direction at the extreme right hand side of this shot.