i have a 2006 250 exc 2 stroke that wont rev right out it stops about 3/4's of the way through the rev's. it had done about 50 hrs so i replaced the piston, plug and fitted a gnarly front pipe and it still did it so took the reads out there fine try'd the jets bigger and smaller fitted another plug and changed the air filter still no joy so phoned my local dealer they said see if theres and petrol in the oil as a crank ceil could be gone but nothing what else can i try?
check the power valve is actuating properly, check coil pack and rectifier are working properly as they can break down under load and cause a weak spark.
just took the front pipe and power valve cover off seems to be working ok even put the pipe back on and started it up as i rev'd it the arm moved upwards
