An experimental study on engine performance parameters and emission gas characteristics for bio-diesel fuels (BDF`s) was performed by using of a specific engine; the type of single-cylinder, four-stroke, water-cooled diesel engine with variable compression ratio adjustment mechanism (the model Farryman A 30 marine, TQ, UK). Specific fuel consumptions (SFC) and soot tendency (smoke %) for various fuel and/or operation conditions were also examined. The BDF`s used were prepared BD 20 and BD 100 together with the commercial diesel fuel (DF) for reference. The established conditions for experiment were 12:1, 14:1, 16:1 and 18:1 for compression ratio (CR), and 1000, 1500, 2000 and 2500 rpm for engine speed. It was found that SFC of BDF`s is increased 1.3~3.7% compared with DF according to the rpm`s; for the smoke %, BDF`s value is reduced significantly up to max. 45.7 % in comparison to that of DF; and while NOx is increased amazingly up to max. 38%, which is too much than the previous results of around 12.0 %. Also, it does not seem that the engine`s power output remains changed significantly according to the fuels used.