how do i de-restrict my 2004 Yamaha DT50 r ???

Its hard to say as it depends on the pipe,but take your jet to the local bike shop and see what they think.i would always start to big and work down so as not to run to lean which can harm the engine.I always have jetting kits so i have a range to try.when you think its running ok get the bike flat out in 3rd gear for 30seconds and kill the engine then pull in the clutch and stop,remove the spark plug and check the colour,should be a nice light brown ,not white or black.Black means its running rich,

mikec
April 2010