Hello guys - I do not normally post here but i'm having a helluva time with my YZ250. Here's the scenario: I've had a recurring problem since i rebuilt it in March, the problem was not there beforehand. (Wiseco crank, rod & main bearings......fresh cylinder plating from US chrome with wiseco piston, all new transmission bearings) The bike runs great until it hits the pipe for just about one second. It shuts off which is very similar to holding down the kill switch. LIfting and re-applying the throttle does nothing. The bike continues to rev down until rpm's reach 0. After that it can be re-started and ridden until it hits the pipe for rougly one second....then it's the same scenario. It can be held wide open in neutral and does not cut out. I've only tried for 2-3 seconds....scared it's gonna fly apart. Here's what i've changed & inspected: Cleaned carb & electrically checked powerjet solenoid - no change Replaced ALL wiring, CDI, coil, kill switch - no change Just replaced stator tonight - no change Fuel tank petcock is not plugged Replaced spark plug - no change Checked carb needle valve - it's working properly Fuel tank vent is not clogged Carb vents are not clogged Any Ideas?