hello all, my son races an Apex MXR Pro 90 and i have an issue with it. i have never encountered this problem before with a 2 stroke so i find it weird. when the quad is running it actually pushes air/fuel out of the carb towards the air filter. At an idle it's very little but at wide open throttle it blows a decent mist. Being premixed this causes the air filter to fill with oil and make a mess but it also leans it out to the point of killing the motor after a few seconds at wide open throttle. It has V-force 3 reeds in it and i have no idea how old they are since they came with the machine when we bought it last year. do think this could be because the reeds aren't closing fully? i have never had this problem with my banshee or blaster and the v force 4 reeds in the banshee are a few years old. let me know what y'all think!

 

I'm no expert in 2 strokes but the reed valve's job is to shut off the crankcase from the carb as pressure in the case rises, so it looks like it isn't doing it. There is bound to be a bit of back flow as the valve won't close until pressure is over atmosphere in the crankcase, but if it is excessive, it has got to be the reeds.

Not sure this is your wide open throttle problem though, as a fuel soaked air filter is going to run rich, not weak.