From what I have read on adjusting the power valve on a 250, the TPS should be disconnected, the ignition turned on to cycle it to the open position (not hi) and the cables adjusted to the mark on the adjuster. However, the 150 barrels have HI written on them at this mark on the barrel. This brings me to question whether merely disconnecting the TPS and cycling to the open position is far enough to adjust the rc valve to the etched HI position.