Hi I have a 1990 Kx 500 wich i bought as a non runner i've rebuilt the engine had the barrel relined to standard size i've set the ignition timing and set the carburettor jetting to standard Main jet 168, Slow/pilot jet 60, needle N28M, needle clip position 3, air screw 1 1/2 turns out.I live in the UK 70 metres above sea level average humidity 60% But the performance out of it it is nothing like it should be, it is really flat lacking power nothing like the arm wrenching beast they are.I had starting problems at first with it flooding all the time i adjusted the float level with a float level gauge and this fixed the problem. The only time it has ran o.k is when i rode off accidently with the fuel off it took off like a rocket just before the fuel in the float bowl ran out, could it be a jetting problem. Any help would be apreciated. Thanks Paul