the problem is clearly lack of fuel,it stalls when you rev it beacause the extra air it gets when the slide lifts up is not what it wants,it needs more fuel too the needle the controls the speed the fuel is sucked in is joined to the slide that controls the air but it doesnt lift out much when first throttled only when the slide is right up.i would say the main jet needs to be bigger or you could try changing the position of the circlip on the needle in the throttle slide also the float level that alters the fuel level in the float bowl can cause this too but its unlikely this would change without you altering it .the problem is that the emission levels these bikes are produced to stick too are so low that all the settings on the carb will be set to make the bike run as lean as possible (using less fuel)taking of the air filter is the last thing it needs this will only cause the engine to get more air !i would first try movint the circlip on the throttle slide to the slot nearest the pointed end of the nedle if that doensnt work try a bigger main jet.if you cannot get a jet then increase the size of the hole in the jet to approx 10 bigger than it is i.e say it has a 100 main jet in it drill the hole to a 110 by using a 1.1mm drill bit ok let me know what happens mate,adam
adam bike doctor, July 2006