So much for compression being a problem. From the Practica Foundation Micro Diesel Project: Micro diesel engine | Practica Foundation
Displacement 18 cm3
Power output 0,6hp at 6000rpm
Cycle two stroke
Compression Variable between 0 and 1:50
Fuel Kerosene, diesel or vegetable oils
Weight of bare engine (approx) 15kg
Cooling Water cooled, air-cooling optional
Speed control Internal governor
Power take-off shaft 1500rpm, 1:4 ratio to crankshaft
Power take-off (2, start shaft) 365 rpm
Specific fuel consumption 300-400gr/hp.h
Fuel cons. at 0,2hp/5700rpm 0.15 l/h
Of course, this engine is too small and can't be bought. And all the available diesels I've found are 250cc or larger-- too big to be legal on a motorized bicycle. And they're all too heavy.
Anybody know which is the better of the 50cc Chinese 2 stroke kits? I'm thinking I might want to tinker...