You can find the year of manufacture of your engine from the code stamped on its cooling air cowl (the orange bit that wraps around the cylinder head). A larger pulley on the engine's crankshaft, and/or a smaller pulley on the transmission, will make it go faster but will reduce its ability to go slowly, climb hills, pull loads, etc. You will end up using lower gears, and for the jobs you currently do in the lowest gear, you'll be in trouble.
