Good day to you all.I'm having some issues with my sons little rm85 its a 2003 model (with a power valve). As soon as I hit the gas it just boggs out on high rpm's ,when I change to 2nd ......good power but as soon as it reach high rpm's the same happens same in 3rd etc. The fuel tank is clean and the carb is clean new air filter and new plug new crank seals and new stock reed valves it has a fuel 2 stroke mix of 40:1 fully synthetic castrol oil.The bike starts very easy cold or hot. I've checked the power valve it seems that its functioning normally when revving it up the valve opens as soon as you get to 3/4 of the throttle +-.......... Please anybody any suggestions? Did anybody experienced the same thing in the past? Thank you .